Kari Anne Bråthen

• Li, Wenhuai; Borer, Elizabeth T.; Seabloom, Eric W.; Stevens, Carly J.; Arnillas, Carlos Alberto & Barrio, Isabel C. [Show all 50 contributors for this article] (2026). Plant species responses to nutrient addition, but not to herbivore exclusion, strengthen over time in global grasslands. Journal of Ecology. ISSN 0022-0477. 114(9). doi: 10.1111/1365-2745.70443. Full text in Research Archive Show summary

  Changes in soil nutrients and herbivore pressure are key drivers of plant community dynamics in grasslands worldwide. Predicting how plant communities will respond to these global change factors requires understanding the responses of individual species, which can be affected by their abundance and frequency within the community, and by characteristics such as their geographical origin (native vs. exotic), life history (annual vs. perennial) and growth form (grass vs. forb). We analysed data from 2414 plant species from 98 grasslands over 13 years (739 site-years) to examine how nutrient addition (fertilised treatment vs. unfertilised control) and herbivore exclusion (fenced treatment vs. unfenced control) alter plant community composition. We quantified species-specific contributions to compositional variation and related these contributions to their dominance, commonness (whether they occurred in one or both treatments) and characteristics. Nutrient addition led to increasing plant community compositional divergence over time, whereas herbivore exclusion had weak and transient effects on plant community composition. Plant species unique to one treatment became increasingly prevalent in nutrient addition treatments but contributed surprisingly little to compositional variation. Most variation was due to common species, particularly those with similar dominance patterns in the two treatments. Indicator species contributed a disproportionately high amount of the compositional variation between treatments; these species were more likely to be dominants, common to both treatments, annuals and exotics. Synthesis. These findings highlight that global change impacts on plant community composition can be driven by shifts in a subset of species. Understanding these species-specific responses is crucial for predicting community dynamics and for biodiversity conservation efforts in the face of ongoing environmental change. Our study demonstrates the utility of identifying key drivers of compositional shifts in grasslands worldwide.

• Pham, Minh Nhat; Armstrong, Claire; Tuomi, Maria & Bråthen, Kari Anne (2026). How dis-services illuminate divergence between "nature's contribution to people" and "ecosystem services" - an assessment of Empetrum nigrum. One Ecosystem. 11. doi: 10.3897/oneeco.11.e141552. Full text in Research Archive
• Spohn, Marie; Arnillas, Carlos Alberto; Bakker, Jonathan D.; Borer, Elizabeth T.; Bråthen, Kari Anne & Cadotte, Marc W. [Show all 35 contributors for this article] (2026). Intense solar radiation constrains plant species richness in global grasslands. Proceedings of the National Academy of Sciences of the United States of America (PNAS). ISSN 0027-8424. 123(6). doi: 10.1073/pnas.2527128123. Full text in Research Archive Show summary

  The search for predictors of plant diversity has challenged scientists for decades. Here we identify intense photosynthetically active radiation (PAR) as a major factor constraining plant species richness in global grasslands. We show that the strength of the negative relationship between species richness and PAR increases with increasing elevation and that species richness is more strongly correlated with intense PAR than with UV-B radiation, climate variables, and atmospheric nitrogen deposition. In addition to species richness, plant biomass was also negatively correlated with PAR at higher elevations, indicating that intense PAR also constrains plant biomass in montane grasslands. Furthermore, we show that the decrease in plant species richness with increasing PAR is mainly caused by a decrease in species richness of forbs, sedges, and rushes. In contrast, species richness of grasses was only negatively correlated with PAR at high elevations, and species richness of legumes was not significantly correlated with PAR. Our results suggest that PAR constrains plant species richness in global grasslands and limits the extent to which plant species of specific functional groups can migrate uphill in response to climate warming.

• Ryde, Ingvild; Halmová, Marika; Bråthen, Kari Anne; Neilson, Elizabeth H.J. & Jónsdóttir, Ingibjörg S. (2025). Intra-specific variability and sex influence allelopathic capacity of Empetrum nigrum. Nordic Journal of Botany (NJB). ISSN 0107-055X. 2025(12). doi: 10.1002/njb.04824. Full text in Research Archive Show summary

  Allelopathic plant species play significant roles in shaping natural ecosystems. While ahigh degree of inter-species variation in allelopathic capacities is commonly reported,variation across intra-specific groups and between dioecious sexes is limited. Here weuse the ecologically important, allelopathic dwarf shrub Empetrum nigrum to assesshow allelopathic capacity varies between intra-specific groups (i.e. the diploid anddioecious ‘nigrum’ group and the tetraploid and synoecious ‘hermaphroditum’ groupof Empetrum) and sex (i.e. male and female plants of the nigrum group). Specifically,we tested Icelandic Empetrum, as its allelopathic nature may influence long-term landdegradation across Icelandic highlands. The allelopathic capacity of Empetrum leaveswas measured in a series of bioassays as the inhibition of seed germination and seedlingroot elongation of the grass Festuca richardsonii. A very strong allelopathic response ofEmpetrum leaves was observed. Intra-specific and sex-related differences in allelopathiccapacity were also detected, with the hermaphroditum group possessing a greater germi-nation inhibitory effect compared to the nigrum group, and males of the nigrum groupinhibited germination more than females. Targeted liquid chromatography-mass spec-trometry (LC-MS) quantification of two known Empetrum allelopathic constituents –Batatasin-III (BIII) and 3,4-dimethoxy-2ʹ,5-d ihydroxybi benzy l (DDB) – showed thatBIII concentrations were significantly higher in leaves from the hermaphroditum groupcompared to the nigrum group, but no differences were observed between males andfemales within the nigrum group. DDB was not detected in the sampled IcelandicEmpetrum population. Our results indicate that Empetrum may differentially impactplant interactions and ecosystem processes depending on the relative abundance ofEmpetrum intra-specific groups and sexes within populations, and that BIII is notsolely responsible for the allelopathic capacity of Icelandic Empetrum.

• Celis, Gerardo; Ehrich, Dorothee; Heskel, Mary; Soininen, Eeva M; Ungar, Peter & Bråthen, Kari Anne (2025). Forbs in Viking lands: the effect of disturbing dominant graminoids on recruitment in tundra grasslands. Oikos. ISSN 0030-1299. doi: 10.1002/oik.11341. Full text in Research Archive Show summary

  Grasslands, by definition, are dominated by graminoids. Nevertheless, forbs also make up a substantial part of vascular plant diversity in grasslands and are important resources of mammalian herbivores. However, forb recruitment is constrained by successful dominant graminoids, limiting access to safe sites for germination. Disturbances created by herbivores can reduce graminoid dominance and favor forb recruitment. Here we hypothesize that intense disturbance, such as that caused by megaherbivores, promotes safe sites for forbs in such graminoid‐dominated grasslands, whereas disturbance by today's herbivores, such as small rodents, may not be sufficiently intense. We selected a total of 80 plots with either of four successful graminoid species in tundra grasslands of the Varanger Peninsula, Norway. The graminoid species were silicon‐poor or rich, and of either mat‐ or bunch‐growth form. Plots were further selected in both rodent disturbed and undisturbed areas. We manually removed the dominant graminoid in half of the plots, mimicking megaherbivore disturbance by reducing both shading capabilities and belowground rhizome and root systems. Results show that forb recruitment was significantly enhanced one year following the manual removal of all four graminoids. This effect on forb recruitment was similar among the four graminoids even though they were associated with distinct plant communities. The rodent disturbance did not enhance forb recruitment. In plots with rodent‐disturbed graminoids, the manual removal enhanced forb recruitment only in plots with silicon‐rich graminoids. Forb recruitment was further enhanced by higher levels of initial species richness, initial forb abundance, and soil moisture. Our findings support the hypothesis that intense disturbance, simulating megaherbivore effects on dominant graminoids, significantly enhances forb recruitment.

• Frainer, André; Jepsen, Jane Uhd; Poste, Amanda Elizabeth; Ims, Rolf Anker; Amundsen, Per-Arne & Asbjørnsen, Einar Johannes [Show all 13 contributors for this article] (2025). Science Plan for Integrating Cross‐Ecosystem Monitoring in the Arctic. Limnology and Oceanography Bulletin. ISSN 1539-607X. p. 1–20. doi: 10.1002/lob.70016. Full text in Research Archive Show summary

  Streams and lakes are nested within, and intimately connected with, the surrounding terrestrial landscape. However, these aquatic components of the catchment are commonly neglected and often not included in studies and management plans that focus on terrestrial ecosystems. Developing an improved understanding of biotic and abiotic connectivity across these ecosystems is key for the advancement of knowledge‐based management of natural ecosystems. Here, we take advantage of existing and extensive long‐term monitoring of the terrestrial food web in the Norwegian Arctic to propose how both new and existing freshwater monitoring can be integrated with terrestrial monitoring to develop a unifying design for adaptive monitoring of low‐Arctic catchments. Specifically, we suggest that relevant cross‐ecosystem linkages between freshwater and terrestrial ecosystems should be integrated in long‐term monitoring, and we outline the methods and timing for how to do this and use the aquatic systems as sentinels for detecting climate‐driven changes. While the plan we present here is tailored for the Norwegian low‐Arctic, it provides an approach that can be more broadly applied (or modified) to monitor many terrestrial–aquatic meta‐ecosystems subjected to impact of climate change around the world.

• Berthelot, Fanny Marie Lou; Stien, Audun; Soininen, Eeva M; Tveraa, Torkild; Böhner, Hanna & Bråthen, Kari Anne (2025). Are Large‐Scale Differences in Temperature and Reindeer Management Regime Affecting the Quality of Reindeer's Summer Forage? Ecology and Evolution. 15(11). doi: 10.1002/ece3.72500. Full text in Research Archive Show summary

  ABSTRACT The chemical balance between essential nutrients and defense compounds in plants determines the quality of the forage available to herbivores and can be modified by both environmental conditions and herbivores themselves. We investigated whether climate and herbivory affect nutrient and defense compound concentrations across plant functional groups. Concentrations of nutrients—nitrogen (N) and phosphorus (P)—and defense compounds—silicon (Si) and phenolics (Ph)—were measured in plant samples from the locally most abundant species, collected in northern Norway across a gradient in summer temperature and different reindeer grazing regimes. Nutrient and defense compound concentrations varied substantially across species and plant functional groups. In addition, nutrients (N, P) declined over the summer, while defense compounds (Si, Ph) accumulated. Sites with a warmer climate had a stronger decrease in nutrient concentrations over the season. We found no evidence that long‐term contrasts in reindeer herbivory intensity affected the average nutritional quality within plant species. Overall, our results suggest that spatial variation in the nutritional quality in Arctic tundra vegetation is mainly determined by the species composition and by consistent changes over the summer season. In comparison, reindeer herbivory and local climate seem to have relatively little impact on the average nutrient and defense compound concentrations of the plant species, suggesting they mainly alter forage quality through effects on the functional and taxonomic composition of the vegetation.

• Maliniemi, Tuija; Kiilunen, Petteri; Bråthen, Kari Anne; Kapfer, Jutta; Rosendal, Torunn Bockelie & Grytnes, John-Arvid [Show all 8 contributors for this article] (2025). Long‐term homogenization of Fennoscandian heathland and tundra vegetation is connected to the expansion of an allelopathic dwarf shrub. Ecography. ISSN 0906-7590. 2025(11). doi: 10.1002/ecog.07921. Full text in Research Archive Show summary

  Boreal and tundra plant communities are expected to change in biodiversity due to increasing global change pressures such as climate warming. One long‐term scenario is increasing compositional similarity, i.e. biotic homogenization, which has been relatively little studied in high‐latitude plant communities. Here, we study how the composition and diversity of heathland and tundra plant communities have changed in northern Fennoscandia over several decades. In 2013–2023, we resurveyed 275 historic vegetation plots, originally surveyed in 1964–1975, with percentage covers for vascular plant, bryophyte and lichen species. We analyzed temporal changes in community composition and diversity across the study area and in different biogeographic zones, continentality‐humidity classes and habitat types. We found a strong homogenization trend across the study area, with plant communities becoming more similar in composition over the decades when all taxa were treated together. The observed homogenization was driven especially by the increased similarity of vascular plant and lichen communities and was largely independent of biogeographic zones or continentality‐humidity gradient. Homogenization was particularly associated with the drastic encroachment of the evergreen dwarf shrub Empetrum nigrum in habitat types originally dominated by other species, and with the decrease in lichen cover. In general, our findings suggest that Fennoscandian heathland and tundra vegetation is transforming towards a more homogeneous evergreen dwarf shrub‐dominated system, which may threaten ecosystem multifunctionality. Our results highlight the importance of exploring biodiversity among different metrics and growth forms to understand the overall changes in heathland and tundra biodiversity.

• Kiilunen, Petteri; Maliniemi, Tuija; Alahuhta, Janne; Grytnes, John-Arvid; Virtanen, Risto & Bråthen, Kari Anne [Show all 11 contributors for this article] (2025). Decades of Change in Vascular Plant Composition in High‐Latitude Ecosystems: Shifting Prevalence of Pollination Strategies. Ecology and Evolution. 15(10). doi: 10.1002/ece3.72288. Full text in Research Archive Show summary

  The composition of high‐latitude plant communities has changed over the past decades in response to several global change drivers. However, less is known about how these compositional long‐term changes are reflected in the total cover of plant species that do or do not interact with pollinators. Using species‐specific indicator values for pollinator dependence and nectar production, we provide empirical evidence on how compositional changes in vascular plant communities over the past 50 years are reflected in the cover of pollinator‐dependent and pollinator‐independent plants, as well as the cover of pollen‐ and nectar‐rewarding and non‐nectar plants, in two ecosystems in northern Fennoscandia. We show that the average cover of pollinator‐independent plants greatly increased in both tundra and herb‐rich forest communities over time. Average cover of pollinator‐dependent plants slightly increased in tundra but decreased in herb‐rich forests. The average cover of pollen‐nectar plants increased in the tundra but decreased in herb‐rich forests over time. At the same time, the cover of non‐nectar plants increased in both ecosystems. The observed changes were strongly driven by the increased cover of evergreen dwarf shrubs in the tundra and the decline of forb cover in herb‐rich forests. The observed changes were comparable between sites that had been disturbed by human land use and sites that remained in a natural or semi‐natural state. Our results suggest that, in terms of average plant coverage, high‐latitude plant communities have broadly become less dependent on insect pollination over the past 50 years. By documenting long‐term changes in the pollination strategies of high‐latitude plant communities, our study underscores the need to explore how shifts in plant community composition are linked to pollination processes and broader plant–pollinator dynamics. We highlight patterns that warrant further investigation and offer perspectives for future research on plant–pollinator interactions in northern ecosystems under global change.

• Rijal, Dilli Prasad; Bråthen, Kari Anne; Brown, Antony; Heintzman, Peter D.; Alsos, Inger Greve & Yoccoz, Nigel (2025). Millennia of Metacommunity Diversification and Homogenization Captured by Sedimentary Ancient <scp>DNA</scp>. Ecology Letters. ISSN 1461-023X. 28(9). doi: 10.1111/ele.70218. Full text in Research Archive Show summary

  ABSTRACT Alpha (α), beta (𝛽), gamma (𝛾) and zeta (𝛇) diversity metrics are complementary in their information, yet insight from this complementarity has yet to be explored. Here we use postglacial lake sediments for reconstructing plant metacommunity diversity patterns using all four metrics. Based on sedimentary ancient DNA data, we find that the metacommunity both diversified (𝛽 spatial ) and homogenised (𝛇) over millennia of ecosystem development, alongside rising taxon richness at both community (α) and metacommunity (𝛾) level. In contrast temporal turnover of taxa (𝛽 temporal ) declined, both at the community and metacommunity level. With taxon appearances exceeding disappearances this suggests the co‐existence of taxa in the communities increased. However, the shared taxa in the metacommunity (𝛇) showed a continuously high temporal turnover, suggesting the taxa contributing to the metacommunity homogenisation were largely transient. That communities homogenised but remained distinctively different over millennia highlights the importance of individual communities in sustaining metacommunity biodiversity.

• Celis, Gerardo; Bråthen, Kari Anne; Ehrich, Dorothee; Paine, Oliver; Sponheimer, Matt & Heskel, Mary [Show all 8 contributors for this article] (2025). Small rodent disturbance impact on Arctic graminoid forage quality. Polar Biology. ISSN 0722-4060. 48(3). doi: 10.1007/s00300-025-03400-x. Full text in Research Archive
• Pham, Minh Nhat; Armstrong, Claire W.; Sims, Charles B. & Bråthen, Kari Anne (2025). When Climate Change Turns Good Plant Bad–A Dynamic Multispecies Model of Reindeer Herding in a Changing Arctic. Environmental and Resource Economics. ISSN 0924-6460. 88, p. 1297–1337. doi: 10.1007/s10640-025-00966-2. Full text in Research Archive
• Bon, Matteo Petit; Beard, Karen H.; Braathen, Kari Anne; Lee, Hanna & Jonsdottir, Ingibjørg (2024). Goose grubbing and warming suppress summer net ecosystem CO2 uptake differentially across high-Arctic tundra habitats. Ecology. ISSN 0012-9658. 106(1). doi: 10.1002/ecy.4498. Full text in Research Archive Show summary

  Environmental changes, such as climate warming and higher herbivory pressure, are altering the carbon balance of Arctic ecosystems; yet, how these drivers modify the carbon balance among different habitats remains uncertain. This hampers our ability to predict changes in the carbon sink strength of tundra ecosystems. We investigated how spring goose grubbing and summer warming—two key environmental-change drivers in the Arctic—alter CO2 fluxes in three tundra habitats varying in soil moisture and plant-community composition. In a full-factorial experiment in high-Arctic Svalbard, we simulated grubbing and warming over two years and determined summer net ecosystem exchange (NEE) alongside its components: gross ecosystem productivity (GEP) and ecosystem respiration (ER). After two years, we found net CO2 uptake to be suppressed by both drivers depending on habitat. CO2 uptake was reduced by warming in mesic habitats, by warming and grubbing in moist habitats, and by grubbing in wet habitats. In mesic habitats, warming stimulated ER (+75%) more than GEP (+30%), leading to a 7.5-fold increase in their CO2 source strength. In moist habitats, grubbing decreased GEP and ER by ~55%, while warming increased them by ~35%, with no changes in summer-long NEE. Nevertheless, grubbing offset peak summer CO2 uptake and warming led to a twofold increase in late summer CO2 source strength. In wet habitats, grubbing reduced GEP (−40%) more than ER (−30%), weakening their CO2 sink strength by 70%. One-year CO2-flux responses were similar to two-year responses, and the effect of simulated grubbing was consistent with that of natural grubbing. CO2-flux rates were positively related to aboveground net primary productivity and temperature. Net ecosystem CO2 uptake started occurring above ~70% soil moisture content, primarily due to a decline in ER. Herein, we reveal that key environmental-change drivers—goose grubbing by decreasing GEP more than ER and warming by enhancing ER more than GEP—consistently suppress net tundra CO2 uptake, although their relative strength differs among habitats. By identifying how and where grubbing and higher temperatures alter CO2 fluxes across the heterogeneous Arctic landscape, our results have implications for predicting the tundra carbon balance under increasing numbers of geese in a warmer Arctic.

• Braathen, Kari Anne; Tuomi, Maria Wilhelmina; Kapfer, Jutta; Böhner, Hanna & Maliniemi, Tuija (2024). Changing species dominance patterns of Boreal-Arctic heathlands: evidence of biotic homogenization. Ecography. ISSN 0906-7590. 2024(6). doi: 10.1111/ecog.07116. Full text in Research Archive Show summary

  Heathlands are extensive systems often dominated by slow-growing and long-lived woody plants. These systems require longer-term studies to capture if and how they are changing over time. In 2020, we resurveyed species richness and cover of vascular plant communities in 139 heathlands along the coastline of northern Fennoscandia, first surveyed during 1965–1975. The first survey included six heathland types, each with dominance – a cover of 25% or more – of the dwarf shrubs Calluna vulgaris, Kalmia procumbens, Betula nana, Vaccinium myrtillus and Empetrum nigrum. The two latter heathland types made up 29% and 48%, respectively, of all heathlands. In addition to the dominant dwarf shrubs giving their names to the heathland types, a few other species qualified as dominant. In the resurvey, all the heathland types had E. nigrum as the single dominant species, except for the heathland formerly dominated by B. nana. Most other species had low cover both at the time of the original survey and the resurvey. Also, the heathland types were species poor at the time of the original survey, with an average of eight vascular plant species per 4 m² and were found equally species poor in the resurvey. Species richness differed between heathland types only at the time of the original survey, and the ratio of species exchange between the two surveys was negatively related to the original cover of E. nigrum. Here we provide a half-century perspective on vegetation change, during which several heathland types in northern Fennoscandia have changed to Empetrum heathlands, reducing the diversity of heathland types across the Boreal to Arctic landscape. As a native plant, E. nigrum cannot be considered invasive, but its allelopathic capacity has likely already modified these heathland ecosystems and will continue to do so, reducing ecosystem multifunctionality across the region.

• Pham, Minh Nhat; Armstrong, Claire W.; Braathen, Kari Anne & Skalska-Tuomi, Maria Wilhelmina (2024). Controlling the stock or the habitat – The crisis of native invasive encroachment in the grazing land of Norwegian reindeer husbandry. Journal of Environmental Management (JEM). ISSN 0301-4797. 370. doi: 10.1016/j.jenvman.2024.122457. Full text in Research Archive Show summary

  Climate change negatively impacts reindeer grazing in Fennoscandia, with the encroachment of <i>Empetrum nigrum</i> (crowberry) being a significant, yet largely unrecognized problem. Crowberry encroachment affects the neighboring palatable vegetation negatively, homogenizing the pasture and decreasing ecosystem biodiversity. Current husbandry management aims are based on sustainable use of the pasture land, yet pasture quality is not considered a central indicator. To prevent overgrazing, reindeer numbers are limited, but as the animals avoid crowberry, this invasive species exacerbates the Norwegian reindeer husbandry's pasture crisis. Herders therefore intervene with two adaptive strategies, supplementary feeding and/or crowberry control. We develop a general three-species bioeconomic model with five variants to understand the economic impact of an invasive species on herbivore husbandry, and the net benefits of the two adaptive measures at the steady state. Our analytical results show that the native invasive encroachment causes a decrease in not only the nutrient-high grazing land but also the optimal herbivore herd and slaughter volume. Supplementary feeding is implemented to increase the herd size, yet the measure further depletes the grazing pasture, making this practice unsustainable. Instead, controlling crowberry protects both the grazing pasture and reindeer herd size. Applying this to the Norwegian reindeer husbandry case, we find crowberry control more cost-effective and less stressful for the pasture land than supplementary feeding. Government subsidies are shown to be essential for restoring herd sizes to the status quo.

• Tuomi, Maria Wilhelmina; Utsi, Tove Hilde Ågnes; Yoccoz, Nigel Gilles; Armstrong, Claire W.; Gonzalez, Victoria & Hagen, Snorre [Show all 12 contributors for this article] (2024). The increase of an allelopathic and unpalatable plant undermines reindeer pasture quality and current management in the Norwegian tundra. Communications Earth & Environment. 5, p. 1–12. doi: 10.1038/s43247-024-01451-2. Full text in Research Archive Show summary

  Ongoing Arctic greening can increase productivity and reindeer pasture quality in the tundra. However, greening may also entail proliferation of unpalatable species, with consequences for pastoral socialecological systems. Here we show extensive greening across 20 reindeer districts in Norway between 2003 and 2020, which has reduced pasture diversity. The allelopathic, evergreen dwarf-shrub crowberry increased its biomass by 60%, with smaller increases of deciduous shrubs and no increase in forbs and graminoids, the most species rich growth forms. There was no evidence for higher reindeer densities promoting crowberry. The current management decision-making process aims at sustainable pasture management but does not explicitly account for pasture changes and reduced diversity. Large-scale shifts towards evergreening and increased allelopathy may thus undermine the resource base for this key Arctic herbivore and the pastoral social-ecological system. Management that is sensitive to changes in pasture diversity could avoid mismanagement of a social-ecological system in transition.

• Spohn, Marie; Bagchi, Sumanta; Biederman, Lori A.; Borer, Elizabeth T.; Braathen, Kari Anne & Bugalho, Miguel N. [Show all 30 contributors for this article] (2023). The positive effect of plant diversity on soil carbon depends on climate. Nature Communications. 14(1). doi: 10.1038/s41467-023-42340-0. Full text in Research Archive Show summary

  Little is currently known about how climate modulates the relationship between plant diversity and soil organic carbon and the mechanisms involved. Yet, this knowledge is of crucial importance in times of climate change and biodiversity loss. Here, we show that plant diversity is positively correlated with soil carbon content and soil carbon-to-nitrogen ratio across 84 grasslands on six continents that span wide climate gradients. The relationships between plant diversity and soil carbon as well as plant diversity and soil organic matter quality (carbon-to-nitrogen ratio) are particularly strong in warm and arid climates. While plant biomass is positively correlated with soil carbon, plant biomass is not significantly correlated with plant diversity. Our results indicate that plant diversity influences soil carbon storage not via the quantity of organic matter (plant biomass) inputs to soil, but through the quality of organic matter. The study implies that ecosystem management that restores plant diversity likely enhances soil carbon sequestration, particularly in warm and arid climates.

• Tuomi, Maria; Murguzur, Francisco Javier Ancin; Hoset, Katrine S.; Soininen, Eeva M; Vesterinen, Eero J. & Utsi, Tove Aagnes [Show all 8 contributors for this article] (2023). Novel frontier in wildlife monitoring: Identification of small rodent species from fecal pellets using near-infrared reflectance spectroscopy (NIRS). Ecology and Evolution. 13(3). doi: 10.1002/ece3.9857. Full text in Research Archive Show summary

  Small rodents are prevalent and functionally important across the world's biomes, making their monitoring salient for ecosystem management, conservation, forestry, and agriculture. There is a growing need for cost-effective and noninvasive methods for large-scale, intensive sampling. Fecal pellet counts readily provide relative abundance indices, and given suitable analytical methods, feces could also allow for the determination of multiple ecological and physiological variables, including community composition. In this context, we developed calibration models for rodent taxonomic determination using fecal near-infrared reflectance spectroscopy (fNIRS). Our results demonstrate fNIRS as an accurate and robust method for predicting genus and species identity of five coexisting subarctic microtine rodent species. We show that sample exposure to weathering increases the method's accuracy, indicating its suitability for samples collected from the field. Diet was not a major determinant of species prediction accuracy in our samples, as diet exhibited large variation and overlap between species. fNIRS could also be applied across regions, as calibration models including samples from two regions provided a good prediction accuracy for both regions. We show fNIRS as a fast and cost-efficient high-throughput method for rodent taxonomic determination, with the potential for cross-regional calibrations and the use on fieldcollected samples. Importantly, appeal lies in the versatility of fNIRS. In addition to rodent population censuses, fNIRS can provide information on demography, fecal nutrients, stress hormones, and even disease. Given the development of such calibration models, fNIRS analytics could complement novel genetic methods and greatly support ecosystem- and interaction-based approaches to monitoring.

• Bon, Matteo Petit; Hansen, Brage Bremset; Loonen, Maarten J.J.E.; Petraglia, Alessandro; Bråthen, Kari Anne & Böhner, Hanna [Show all 11 contributors for this article] (2023). Long-term herbivore removal experiments reveal different impacts of geese and reindeer on vegetation and ecosystem CO2-fluxes in high-Arctic tundra. BioRxiv. ISSN 0362-4331. doi: 10.1101/2023.01.27.525821. Full text in Research Archive Show summary

  Given the current and anticipated rates of global change, with associated shifts in herbivore population densities, understanding the role of different herbivores in shaping ecosystem structure and processes is critical for predicting ecosystem responses. Here, we examined the controls exerted by migratory geese and resident, non-migratory ungulates, two dominating yet functionally contrasting herbivores, on the rapidly warming Arctic tundra. We collected vegetation and ecosystem carbon flux data at peak plant growing season in the two longest running herbivore removal experiments in high-Arctic Svalbard. Herbivore exclosures had been set up independently in a wet habitat utilised by barnacle geese (Branta leucopsis) in summer and in mesic-to-dry habitats utilised by wild reindeer (Rangifer tarandus platyrhynchus) year-round. Excluding geese produced vegetation state transitions from heavily grazed, moss-dominated (4 g m-2 dry weight of live aboveground vascular plants) to ungrazed, graminoid-dominated (60 g m-2; after 4-yr exclusion) and then horsetail-dominated (150 g m-2; after 15-yr exclusion) tundra. This caused large increases in vegetation carbon and nitrogen pools, dead biomass and moss-layer depth. Modifications in nitrogen concentrations and carbon-to-nitrogen ratios of vegetation and soil suggested overall slower nutrient cycling rates in the short-term absence of geese. Long-term goose removal quadrupled the net ecosystem carbon sequestration by increasing gross ecosystem photosynthesis more than ecosystem respiration. Excluding reindeer for 21 years also produced detectable, but weaker, increases in live and dead biomass, vegetation carbon and nitrogen pools, moss-layer depth and ecosystem respiration. Yet, reindeer removal did not alter the chemistry of either vegetation or soil, nor net ecosystem carbon sequestration. Our findings suggest that, though both herbivores were key drivers of ecosystem structure and processes, localised effects of geese, highly concentrated in space and time, are larger than those exerted by more widely dispersed reindeer. We illustrate that the impacts of herbivory across the tundra landscape are contingent on the habitat utilised for foraging, its sensitivity, the exerted grazing pressure, and herbivore characteristics. Our results underscore the conspicuous heterogeneity in how Arctic herbivores control ecosystem functioning, with important implications under current and future global change.

• Breitschopf, Eva & Bråthen, Kari Anne (2023). Perception and appreciation of plant biodiversity among experts and laypeople. People and Nature. 5(2), p. 826–838. doi: 10.1002/pan3.10455. Full text in Research Archive Show summary

  <p>1. Plant biodiversity, which is fundamental for the delivery of ecosystem services, is in decline. Yet, knowledge about how plant biodiversity is perceived and appreciated is scarce. <p>2. We studied biologists' and laypeople's perception and appreciation for plant communities that differ in plant biodiversity,using ranges of plant biodiversity known to affect ecosystem services. We investigate species richness, species turnover and species evenness. A questionnaire based on photographs displaying artificial plant communities was used. <p>3. Perceived biodiversity was 12% more often congruent with actual biodiversity for biologists than for laypeople. Species richness was perceived congruently with actual species richness by 77% of all respondents, compared with 27% for species evenness and 29% for species turnover. Appreciation for the displayed communities correlated positively with their actual plant biodiversity, except for species turnover. Appreciation always correlated positively with perceived plant biodiversity and even stronger than with actual plant biodiversity. This was not the case for species richness, for which perceived and actual biodiversity were most often congruent. <p>4. Our results suggest that plant biodiversity is perceived most accurately when changes in species richness are considered, while changes in species evenness and species turnover are perceived less accurately. The respondents' answers indicate that perceived higher plant biodiversity is appreciated more than perceived lower plant biodiversity, even when perceived and actual plant biodiversity are not congruent. <p>5. We corroborate findings that people value plant biodiversity per se. But we also find that people largely perceive species evenness and turnover with low accuracy; and that people have low appreciation for these biodiversity dimensions that are lesser known but essential to ecosystem functioning. Our finding that biologists have higher accuracy in perceiving biodiversity suggests that biodiversity literacy is key to increasing people's awareness of changes in plant biodiversity.

• Mikryukov, Vladimir; Dulya, Olesya; Zizka, Alexander; Bahram, Mohammad; Hagh-Doust, Niloufar & Anslan, Sten [Show all 106 contributors for this article] (2023). Connecting the multiple dimensions of global soil fungal diversity. Science Advances. 9(48). doi: 10.1126/sciadv.adj8016. Full text in Research Archive Show summary

  How the multiple facets of soil fungal diversity vary worldwide remains virtually unknown, hindering the management of this essential species-rich group. By sequencing high-resolution DNA markers in over 4000 topsoil samples from natural and human-altered ecosystems across all continents, we illustrate the distributions and drivers of different levels of taxonomic and phylogenetic diversity of fungi and their ecological groups. We show the impact of precipitation and temperature interactions on local fungal species richness (alpha diversity) across different climates. Our findings reveal how temperature drives fungal compositional turnover (beta diversity) and phylogenetic diversity, linking them with regional species richness (gamma diversity). We integrate fungi into the principles of global biodiversity distribution and present detailed maps for biodiversity conservation and modeling of global ecological processes.

• Pugnaire, Francisco I.; Aares, Karoline Helene; Alifriqui, Mohamed; Bråthen, Kari Anne; Kindler, Christian & Schöb, Christian [Show all 7 contributors for this article] (2023). Home-field advantage effects in litter decomposition is largely linked to litter quality. Soil Biology and Biochemistry. ISSN 0038-0717. 184. doi: 10.1016/j.soilbio.2023.109069. Full text in Research Archive Show summary

  Climate change and associated environmental alterations affect plant communities, potentially decoupling links between plants and their associated soil microbial communities. This may in turn affect processes like litter decomposition, an important function that controls nutrient and carbon cycling as well as many other ecosystem processes. Microbial decomposers have been proposed to specialize, being able to easier decompose litter from its ‘home’ community than litter from other communities, in what is termed the home field advantage (HFA) hypothesis. We report a litter decomposition experiment including four alpine meadow communities spread along a geographical gradient that ranged from the Atlas in Morocco to the Iberian Peninsula to the Swiss Alps. We tested whether litter decomposition rate would differ depending on litter and soil origin, expecting interactions between litter and soil microbial communities to be at the core of responses. We expected to find HFA in all four alpine communities. HFA ranged from very negative to neutral to positive along our geographical gradient, in a variation that could be attributed to the interaction of microbial communities with soil and plant traits, and linked to the relative abundance of microbial groups performing specific functions. Litter decomposition depended on litter quality and on the fungal community, which seemed adapted to deal with poor-quality, recalcitrant litter, leading to HFA. Climate plays a role as well, indirectly through plant community composition. Phyllosphere communities competed with soil communities when in interaction, a fact that may have blurred results of some previous HFA experiments. In summary, there is a clear HFA in systems with low-quality litter that requires a specialised fungal community to maximize decomposition. By contrast, high-quality, easy to decompose litter would be dealt with by any decomposer community, not showing evidence of HFA.

• Bon, Matteo Petit; Hansen, Brage Bremset; Loonen, Maarten J. J. E; Petraglia, Alessandro; Braathen, Kari Anne & Böhner, Hanna [Show all 11 contributors for this article] (2023). Long-term herbivore removal experiments reveal how geese and reindeer shape vegetation and ecosystem CO2-fluxes in high-Arctic tundra. Journal of Ecology. ISSN 0022-0477. 111(12), p. 2627–2642. doi: 10.1111/1365-2745.14200. Full text in Research Archive Show summary

  Given the current rates of climate change, with associated shifts in herbivore population densities, understanding the role of different herbivores in ecosystem functioning is critical for predicting ecosystem responses. Here, we examined how migratory geese and resident, non-migratory reindeer—two dominating yet functionally contrasting herbivores—control vegetation and ecosystem processes in rapidly warming Arctic tundra. We collected vegetation and ecosystem carbon (C) flux data at peak plant growing season in the two longest running, fully replicated herbivore removal experiments found in high-Arctic Svalbard. Experiments had been set up independently in wet habitat utilised by barnacle geese Branta leucopsis in summer and in moist-to-dry habitat utilised by wild reindeer Rangifer tarandus platyrhynchus year-round. Excluding geese induced vegetation state transitions from heavily grazed, moss-dominated (only 4 g m−2 of live above-ground vascular plant biomass) to ungrazed, graminoid-dominated (60 g m−2 after 4-year exclusion) and horsetail-dominated (150 g m−2 after 15-year exclusion) tundra. This caused large increases in vegetation C and nitrogen (N) pools, dead biomass and moss-layer depth. Alterations in plant N concentration and CN ratio suggest overall slower plant community nutrient dynamics in the short-term (4-year) absence of geese. Long-term (15-year) goose removal quadrupled net ecosystem C sequestration (NEE) by increasing ecosystem photosynthesis more than ecosystem respiration (ER). Excluding reindeer for 21 years also produced detectable increases in live above-ground vascular plant biomass (from 50 to 80 g m−2; without promoting vegetation state shifts), as well as in vegetation C and N pools, dead biomass, moss-layer depth and ER. Yet, reindeer removal did not alter the chemistry of plants and soil or NEE. Synthesis. Although both herbivores were key drivers of ecosystem structure and function, the control exerted by geese in their main habitat (wet tundra) was much more pronounced than that exerted by reindeer in their main habitat (moist-to-dry tundra). Importantly, these herbivore effects are scale dependent, because geese are more spatially concentrated and thereby affect a smaller portion of the tundra landscape compared to reindeer. Our results highlight the substantial heterogeneity in how herbivores shape tundra vegetation and ecosystem processes, with implications for ongoing environmental change.

• Bon, Matteo Petit; Bråthen, Kari Anne; Ravolainen, Virve; Ottaviani, Gianluigi; Böhner, Hanna & Jonsdottir, Ingibjørg (2023). Herbivory and warming have opposing short-term effects on plant-community nutrient levels across high-Arctic tundra habitats. Journal of Ecology. ISSN 0022-0477. 111(7), p. 1514–1530. doi: 10.1111/1365-2745.14114. Full text in Research Archive Show summary

  Environmental changes can rapidly alter standing biomass in tundra plant communities; yet, to what extent can they modify plant-community nutrient levels? Nutrient levels and their changes can affect biomass production, nutrient cycling rates and nutrient availability to herbivores. We examined how environmental perturbations alter Arctic plant-community leaf nutrient concentrations (percentage of dry mass, i.e. resource quality) and nutrient pools (absolute mass per unit area, i.e. resource quantity). We experimentally imposed two different types of environmental perturbations in a high-Arctic ecosystem in Svalbard, spanning three habitats differing in soil moisture and plant-community composition. We mimicked both a pulse perturbation (a grubbing event by geese in spring) and a press perturbation (a constant level of summer warming). After 2 years of perturbations, we quantified peak-season nitrogen and phosphorus concentrations in 1268 leaf samples from the most abundant vascular plant species. We derived community-weighted nutrient concentrations and total amount of nutrients (pools) for whole plant communities and individual plant functional types (PFTs). Spring grubbing increased plant-community nutrient concentrations in mesic (+13%) and wet (+8%), but not moist, habitats, and reduced nutrient pools in all habitats (moist: −49%; wet, mesic: −31% to −37%). Conversely, summer warming reduced plant-community nutrient concentrations in mesic and moist (−10% to −12%), but not wet, habitats and increased nutrient pools in moist habitats (+50%). Fast-growing PFTs exhibited nutrient-concentration responses, while slow-growing PFTs generally did not. Grubbing enhanced nutrient concentrations of forbs and grasses in wet habitats (+20%) and of horsetails and grasses in mesic habitats (+19–23%). Conversely, warming decreased nutrient concentrations of horsetails in wet habitats (−15%) and of grasses, horsetails and forbs in moist habitats (−12% to −15%). Nutrient pools held by each PFT were less affected, although the most abundant PFTs responded to perturbations. Synthesis. Arctic plant-community nutrient levels can be rapidly altered by environmental changes, with consequences for short-term process rates and plant-herbivore interactions. Community-level responses in nutrient concentrations and pools were opposing and differed among habitats and PFTs. Our findings have implications for how we understand herbivory- and warming-induced shifts in the fine-scaled distribution of resource quality and quantity within and across tundra habitats.

• Lindén, Elin; Beest, Mariska te; Aubreu, Ilka; Moritz, Thomas; Sundqvist, Maja K. & Barrio, Isabel C. [Show all 44 contributors for this article] (2022). Circum-Arctic distribution of chemical anti-herbivore compounds suggests biome-wide trade-off in defence strategies in Arctic shrubs. Ecography. ISSN 0906-7590. 2022(11). doi: 10.1111/ecog.06166. Full text in Research Archive Show summary

  Spatial variation in plant chemical defence towards herbivores can help us understand variation in herbivore top–down control of shrubs in the Arctic and possibly also shrub responses to global warming. Less defended, non-resinous shrubs could be more influenced by herbivores than more defended, resinous shrubs. However, sparse field measurements limit our current understanding of how much of the circum-Arctic variation in defence compounds is explained by taxa or defence functional groups (resinous/non-resinous). We measured circum-Arctic chemical defence and leaf digestibility in resinous (Betula glandulosa, B. nana ssp. exilis) and non-resinous (B. nana ssp. nana, B. pumila) shrub birches to see how they vary among and within taxa and functional groups. Using liquid chromatography–mass spectrometry (LC–MS) metabolomic analyses and in vitro leaf digestibility via incubation in cattle rumen fluid, we analysed defence composition and leaf digestibility in 128 samples from 44 tundra locations. We found biogeographical patterns in anti-herbivore defence where mean leaf triterpene concentrations and twig resin gland density were greater in resinous taxa and mean concentrations of condensing tannins were greater in non-resinous taxa. This indicates a biome-wide trade-off between triterpene- or tannin-dominated defences. However, we also found variations in chemical defence composition and resin gland density both within and among functional groups (resinous/non-resinous) and taxa, suggesting these categorisations only partly predict chemical herbivore defence. Complex tannins were the only defence compounds negatively related to in vitro digestibility, identifying this previously neglected tannin group as having a potential key role in birch anti-herbivore defence. We conclude that circum-Arctic variation in birch anti-herbivore defence can be partly derived from biogeographical distributions of birch taxa, although our detailed mapping of plant defence provides more information on this variation and can be used for better predictions of herbivore effects on Arctic vegetation.rotected area networks help species respond to climate warming. However, the contribution of a site’s environmental and conservation-relevant characteristics to these responsesis not well understood. We investigated how composition of nonbreeding waterbird communities (97 species) in the European Union Natura 2000 (N2K) network (3018 sites)changed in response to increases in temperature over 25 years in 26 European countries.We measured community reshuffling based on abundance time series collected under theInternational Waterbird Census relative to N2K sites’ conservation targets, funding, designation period, and management plan status. Waterbird community composition in sitesexplicitly designated to protect them and with management plans changed more quickly inresponse to climate warming than in other N2K sites. Temporal community changes werenot affected by the designation period despite greater exposure to temperature increaseinside late-designated N2K sites. Sites funded under the LIFE program had lower climate-driven community changes than sites that did not received LIFE funding. Our findingsimply that efficient conservation policy that helps waterbird communities respond to cli-mate warming is associated with sites specifically managed for waterbirds. climate adaptation, colonization, conservation policy, distribution change, EU Birds Directive, LIFE program,wetland. Arctic, Betula, birch, herbivory, metabolomics, plant chemical defence, shrubs, tundra

• Brown, Antony; Rijal, Dilli Prasad; Heintzman, Peter D.; Clarke, Charlotte, L.; Blankholm, Hans Peter & Høeg, Helge Irgens [Show all 10 contributors for this article] (2022). Paleoeconomy more than demography determined prehistoric human impact in Arctic Norway. PNAS Nexus. 1(5), p. 1–11. doi: 10.1093/pnasnexus/pgac209. Full text in Research Archive Show summary

  Population size has increasingly been taken as the driver of past human environmental impact worldwide, and particularly in the Arctic. However, sedimentary ancient DNA (sedaDNA), pollen and archaeological data show that over the last 12,000 years, paleoeconomy and culture determined human impacts on the terrestrial ecology of Arctic Norway. The large Mortensnes site complex (Ceavccagea ¯dgi, 70◦N) has yielded the most comprehensive multiproxy record in the Arctic to date. The site saw occupation from the Pioneer period (c. 10,000 cal. years BP) with more intensive use from c. 4,200 to 2,000 cal. years BP and after 1,600 cal. years BP. Here, we combine on-site environmental archaeology with a near-site lake record of plant and animal sedaDNA. The rich animal sedaDNA data (42 taxa) and on-site faunal analyses reveal switches in human dietary composition from early-Holocene fish + marine mammals, to mixed marine + reindeer, then finally to marine + reindeer + domesticates (sheep, cattle, pigs), with highest reindeer concentrations in the last millennium. Archaeological evidence suggests these changes are not directly driven by climate or variation in population densities at the site or in the region, but rather are the result of changing socio-economic activities and culture, probably reflecting settlers’ origins. This large settlement only had discernable effects on its hinterland in the last 3,600 years (grazing) and more markedly in the last 1,000 years through reindeer keeping/herding and, possibly domestic stock. Near-site sedaDNA can be linked to and validate the faunal record from archaeological excavations, demonstrating that environmental impacts can be assessed at a landscape scale.

• Alsos, Inger Greve; Rijal, Dilli Prasad; Ehrich, Dorothee; Karger, Dirk Nikolaus; Yoccoz, Nigel & Heintzman, Peter D. [Show all 16 contributors for this article] (2022). Postglacial species arrival and diversity buildup of northern ecosystems took millennia. Science Advances. 8(39), p. 1–14. doi: 10.1126/sciadv.abo7434. Full text in Research Archive Show summary

  What drives ecosystem buildup, diversity, and stability? We assess species arrival and ecosystem changes across 16 millennia by combining regional-scale plant sedimentary ancient DNA from Fennoscandia with near-complete DNA and trait databases. We show that postglacial arrival time varies within and between plant growth forms. Further, arrival times were mainly predicted by adaptation to temperature, disturbance, and light. Major break points in ecological trait diversity were seen between 13.9 and 10.8 calibrated thousand years before the present (cal ka BP), as well as break point in functional diversity at 12.0 cal ka BP, shifting from a state of ecosystem buildup to a state where most habitat types and biotic ecosystem components were in place. Trait and functional diversity stabilized around 8 cal ka BP, after which both remained stable, although changes in climate took place and species inflow continued. Our ecosystem reconstruction indicates a millennial-scale time phase of formation to reach stable and resilient levels of diversity and functioning.

• Tedersoo, Leho; Mikryukov, Vladimir; Zizka, Alexander; Bahram, Mohammad; Hagh-Doust, Niloufar & Anslan, Sten [Show all 104 contributors for this article] (2022). Global patterns in endemicity and vulnerability of soil fungi. Global Change Biology. ISSN 1354-1013. 28, p. 6696–6710. doi: 10.1111/gcb.16398. Full text in Research Archive Show summary

  Fungi are highly diverse organisms, which provide multiple ecosystem services. However, compared with charismatic animals and plants, the distribution patterns and conservation needs of fungi have been little explored. Here, we examined endemicity patterns, global change vulnerability and conservation priority areas for functional groups of soil fungi based on six global surveys using a high-resolution, long-read metabarcoding approach. We found that the endemicity of all fungi and most functional groups peaks in tropical habitats, including Amazonia, Yucatan, West-Central Africa, Sri Lanka, and New Caledonia, with a negligible island effect compared with plants and animals. We also found that fungi are predominantly vulnerable to drought, heat and land-cover change, particularly in dry tropical regions with high human population density. Fungal conservation areas of highest priority include herbaceous wetlands, tropical forests, and woodlands. We stress that more attention should be focused on the conservation of fungi, especially root symbiotic arbuscular mycorrhizal and ectomycorrhizal fungi in tropical regions as well as unicellular early-diverging groups and macrofungi in general. Given the low overlap between the endemicity of fungi and macroorganisms, but high conservation needs in both groups, detailed analyses on distribution and conservation requirements are warranted for other microorganisms and soil organisms.

• Bon, Matteo Petit; Inga, Katarina Gunnarsdotter; Utsi, Tove Aagnes; Jonsdottir, Ingibjørg & Bråthen, Kari Anne (2021). Forage quality in tundra grasslands under herbivory: Silicon-based defences, nutrients and their ratios in grasses. Journal of Ecology. ISSN 0022-0477. 110(1), p. 129–143. doi: 10.1111/1365-2745.13790. Full text in Research Archive Show summary

  1. Herbivore-induced changes in both leaf silicon-based defence and nutrient levels are potential mechanisms through which grazers alter the quality of their own grass supply. In tundra grasslands, herbivores have been shown to increase nutrient contents of grasses; yet, it is an open question whether they also increase grass silicon-based defence levels. Here, we asked if, and to what extent, herbivores affect silicon content and silicon:nutrient ratios of grasses found in tundra grasslands.<p> <p>2. We performed an herbivore-interaction field-experiment spanning four tundragrassland sites. At each site, we established reindeer-open and reindeer-exclusion plots in tundra-patches that had been disturbed or not by small rodents during the previous winter, for a total of 96 plots. We randomly collected over 1,150 leaf samples of inherently silicon-rich and silicon-poor grass species throughout a growing season and analysed silicon, nitrogen and phosphorus contents of each leaf. <p>3. Small-rodent winter disturbance did not affect grass silicon content, but increased grass quality (i.e. lowered silicon:nutrient ratios) by enhancing nutrient levels of both silicon-rich (+20%–22%) and silicon-poor (+26%–34%) grasses. Reindeer summer herbivory increased the quality of silicon-rich grasses by decreasing their silicon content (−7%). However, the two herbivores together offset both these quality increments in silicon-rich grasses, thus reducing their quality towards the level of those found in the absence of herbivores and further enhancing their silicon:nutrient ratios (+13%–22%) relative to silicon-poor grasses.<p> 4. Synthesis. We provide the first community-level, field-based assessment of how herbivory-driven changes in both leaf silicon-based defence and nutrient levels alter grass-forage quality in tundra grasslands. Herbivores did not promote a net silicon accumulation in grasses, but rather enhanced their overall quality. Yet, the magnitude of these quality increments varied depending on the herbivore(s)

• Murguzur, Francisco Javier Ancin; Tarroux, Arnaud; Bråthen, Kari Anne; Bustamante, Paco & Descamps, Sebastien (2021). Using near-infrared reflectance spectroscopy (NIRS) to estimate carbon and nitrogen stable isotope composition in animal tissues. Ecology and Evolution. 11(15), p. 10483–10488. doi: 10.1002/ece3.7851. Full text in Research Archive Show summary

  1. Stable isotopes analysis (SIA) of carbon and nitrogen provides valuable information about trophic interactions and animal feeding habits. 2. We used near-infrared reflectance spectroscopy (NIRS) and support vector machines (SVM) to develop a model for screening isotopic ratios of carbon and nitrogen (δ13C and δ15N) in samples from living animals. We applied this method on dried blood samples from birds previously analyzed for δ13C and δ15N to test whether NIRS can be applied to accurately estimate isotopic ratios. 3. Our results show a prediction accuracy of NIRS (R2 > 0.65, RMSEP < 0.28) for both δ13C and δ15N, representing a 12% of the measurement range in this study. 4. Our study suggests that NIRS can provide a time- and cost-efficient method to evaluate stable isotope ratios of carbon and nitrogen when substantial differences in δ13C or δ15N are expected, such as when discriminating among different trophic levels in diet.

• Bråthen, Kari Anne; Pugnaire, Francisco I & Bardgett, Richard D (2021). The paradox of forbs in grasslands and the legacy of the mammoth steppe. Frontiers in Ecology and the Environment. ISSN 1540-9295. doi: 10.1002/fee.2405. Full text in Research Archive Show summary

  The grassland biome supports an enormous diversity of life and includes ecosystems used extensively by humans. Although graminoids lend grasslands their characteristic appearance, forbs are largely responsible for their taxonomic, phylogenetic, and functional diversity. In terms of abundance, however, forbs often play a subordinate role relative to graminoids. Yet this may be a relatively recent phenomenon; evidence is mounting that forbs comprised a major part of the richness of, and were abundant in, the extensive and highly productive grasslands of the Pleistocene, the so-called “mammoth steppe”. As a legacy of their past prevalence under intensive grazing by megafaunal herbivores, we hypothesize that forbs were, and still are, dependent on niche construction by large mammalian herbivores. We suggest that the high species richness of forbs in grasslands globally merits greater research and conservation attention, and management actions tailored to sustain their abundance and diversity.

• Gonzalez, Victoria; Lindgård, Bente; Reiersen, Rigmor; Hagen, Snorre & Bråthen, Kari Anne (2021). Niche construction mediates climate effects on recovery of tundra heathlands after extreme event. PLOS ONE. 16(2), p. 1–14. doi: 10.1371/journal.pone.0245929. Full text in Research Archive Show summary

  Climate change is expected to increase the frequency and intensity of extreme events in northern ecosystems. The outcome of these events across the landscape, might be mediated by species effects, such as niche construction, with likely consequences on vegetation resilience. To test this hypothesis, we simulated an extreme event by removing aboveground vegetation in tundra heathlands dominated by the allelopathic dwarf shrub Empetrum nigrum, a strong niche constructor. We tested the hypothesis under different climate regimes along a 200-km long gradient from oceanic to continental climate in Northern Norway. We studied the vegetation recovery process over ten years along the climatic gradient. The recovery of E. nigrum and subordinate species was low and flattened out after five years at all locations along the climatic gradient, causing low vegetation cover at the end of the study in extreme event plots. Natural seed recruitment was low at all sites, however, the addition of seeds from faster growing species did not promote vegetation recovery. A soil bioassay from 8 years after the vegetation was removed, suggested the allelopathic effect of E. nigrum was still present in the soil environment. Our results provide evidence of how a common niche constructor species can dramatically affect ecosystem recovery along a climatic gradient after extreme events in habitats where it is dominant. By its extremely slow regrowth and it preventing establishment of faster growing species, this study increases our knowledge on the possible outcomes when extreme events harm niche constructors in the tundra.

• Bon, Matteo Petit; Bøhner, Hanna; Bråthen, Kari Anne; Ravolainen, Virve & Jonsdottir, Ingibjørg (2021). Variable responses of carbon and nitrogen contents in vegetation and soil to herbivory and warming in high-Arctic tundra. Ecosphere. 12(9). doi: 10.1002/ecs2.3746. Full text in Research Archive Show summary

  Chemical responses of tundra vegetation and tundra soil to environmental changes are likely to differ, with implications for ecosystem functioning, yet they are rarely compared. Here, we aimed at comparing sensitivity and magnitude of short-term carbon and nitrogen responses of three main tundra ecosystem compartments: vascular plants, mosses, and soil, to two environmental perturbations: herbivore disturbance and warming. In a full-factorial field experiment in the high-Arctic Svalbard, we simulated herbivore disturbance as spring grubbing activity by pink-footed geese (Anser brachyrhynchus) and passively increased summer temperatures using open-top chambers. Manipulations were set up within three habitats that differ in soil moisture and carried out for two consecutive growing seasons. Overall, we found small and few significant responses to herbivore disturbance and warming, suggesting that carbon and nitrogen contents of high-Arctic ecosystems are relatively resistant to these perturbations, at least in the short term. However, the three ecosystem compartments still differed in their sensitivity to perturbations (vascular plants > soil > mosses), and this was exacerbated by their differential sensitivity across habitats (mesic > moist > wet). Also, while vascular plants responded to herbivore disturbance in mesic and wet habitats and to warming in mesic and moist habitats, soil and mosses only responded to herbivore disturbance in mesic and wet habitats, respectively. Responses to treatments were generally consistent across the two growing seasons, despite great differences in temperature conditions and large between-year variations in the chemical composition of the three ecosystem compartments. These findings highlight the potential for environmental perturbations to have small, yet differential short-term impacts on the carbon and nitrogen contents of vascular plants, mosses, and soil, both within and between tundra habitats. Our results imply that assessments of a single ecosystem compartment in a given context cannot be extrapolated to the whole ecosystem, thus stressing the importance of considering both vegetation and soil carbon and nitrogen responses, and how they display across habitats, in order to better understand how environmental changes might affect biogeochemical processes in the tundra. Longer-term studies should dig deeper into the relative role of (simulated) global change drivers vs. natural inter-annual climatic fluctuations for tundra ecosystem carbon and nitrogen dynamics.

• Tedersoo, Leho; Mikryukov, Vladimir; Anslan, Sten; Bahram, Mohammad; Khalid, Abdul Nasir & Corrales, Adriana [Show all 95 contributors for this article] (2021). The Global Soil Mycobiome consortium dataset for boosting fungal diversity research. Fungal diversity. ISSN 1560-2745. 111(1), p. 573–588. doi: 10.1007/s13225-021-00493-7. Full text in Research Archive Show summary

  Fungi are highly important biotic components of terrestrial ecosystems, but we still have a very limited understanding about their diversity and distribution. This data article releases a global soil fungal dataset of the Global Soil Mycobiome consortium (GSMc) to boost further research in fungal diversity, biogeography and macroecology. The dataset comprises 722,682 fungal operational taxonomic units (OTUs) derived from PacBio sequencing of full-length ITS and 18S-V9 variable regions from 3200 plots in 108 countries on all continents. The plots are supplied with geographical and edaphic metadata. The OTUs are taxonomically and functionally assigned to guilds and other functional groups. The entire dataset has been corrected by excluding chimeras, index-switch artefacts and potential contamination. The dataset is more inclusive in terms of geographical breadth and phylogenetic diversity of fungi than previously published data. The GSMc dataset is available over the PlutoF repository.

• Rijal, Dilli Prasad; Heintzman, Peter D.; Lammers, Youri; Yoccoz, Nigel; Lorberau, Kelsey & Pitelkova, Iva [Show all 16 contributors for this article] (2021). Sedimentary ancient DNA shows terrestrial plant richness continuously increased over the Holocene in northern Fennoscandia. Science Advances. 7(31). doi: 10.1126/sciadv.abf9557. Full text in Research Archive Show summary

  The effects of climate change on species richness are debated but can be informed by the past. Here, we generated a sedimentary ancient DNA dataset covering 10 lakes and applied novel methods for data harmonization. We assessed the impact of Holocene climate changes and nutrients on terrestrial plant richness in northern Fennoscandia. We find that richness increased steeply during the rapidly warming Early Holocene. In contrast to findings from most pollen studies, we show that richness continued to increase thereafter, although the climate was stable, with richness and the regional species pool only stabilizing during the past three millennia. Furthermore, overall increases in richness were greater in catchments with higher soil nutrient availability. We suggest that richness will increase with ongoing warming, especially at localities with high nutrient availability and assuming that human activity remains low in the region, although lags of millennia may be expected.

• Bon, Matteo Petit; Bohner, Hanna; Kaino, Sissel; Moe, Torunn & Bråthen, Kari Anne (2020). One leaf for all: Chemical traits of single leaves measured at the leaf surface using near-infrared reflectance spectroscopy. Methods in Ecology and Evolution. 00. doi: 10.1111/2041-210X.13432. Full text in Research Archive Show summary

  1. The leaf is an essential unit for measures of plant ecological traits. Yet, measures of plant chemical traits are often achieved by merging several leaves, masking potential foliar variation within and among plant individuals. This is also the case with cost‐effective measures derived using near‐infrared reflectance spectroscopy (NIRS). The calibration models developed for converting NIRS spectral information to chemical traits are typically based on spectra from merged and milled leaves. In this study, we ask whether such calibration models can be applied to spectra derived from whole leaves, providing measures of chemical traits of single leaves.<p><p> 2. We sampled cohorts of single leaves from different biogeographic regions, growth forms, species and phenological stages to include variation in leaf and chemical traits. For each cohort, we first sampled NIRS spectra from each whole, single leaf, including leaf sizes down to Ø 4 mm (the minimum area of our NIRS application). Next, we merged, milled and tableted the leaves and sampled spectra from the cohort as a tablet. We applied arctic–alpine calibration models to all spectra and derived chemical traits. Finally, we evaluated the performance of the models in predicting chemical traits of whole, single leaves by comparing the traits derived at the level of leaves to that of the tablets.<p><p> 3. We found that the arctic–alpine calibration models can successfully be applied to single, whole leaves for measures of nitrogen (<i>R</i>² = 0.88, RMSE = 0.824), phosphorus (<i>R</i>² = 0.65, RMSE = 0.081) and carbon (<i>R</i>² = 0.78, RMSE = 2.199) content. For silicon content, we found the method acceptable when applied to silicon‐rich growth forms (<i>R</i>² = 0.67, RMSE = 0.677). We found a considerable variation in chemical trait values among leaves within the cohorts.<p><p> 4. This time‐ and cost‐efficient NIRS application provides non‐destructive measures of a set of chemical traits in single, whole leaves, including leaves of small sizes. The application can facilitate research into the scales of variability of chemical traits and include intra‐individual variation. Potential trade‐offs among chemical traits and other traits within the leaf unit can be identified and be related to ecological processes. In sum, this NIRS application can facilitate further ecological understanding of the role of leaf chemical traits.

• Tuomi, Maria; Väisänen, Maria; Ylänne, H; Brearley, Francis Q.; Barrio, Isabel C. & Bråthen, Kari Anne [Show all 17 contributors for this article] (2020). Stomping in silence: Conceptualizing trampling effects on soils in polar tundra. Functional Ecology. ISSN 0269-8463. 35, p. 306–317. doi: 10.1111/1365-2435.13719. Full text in Research Archive Show summary

  Ungulate trampling modifies soils and interlinked ecosystem functions across biomes. Until today, most research has focused on temperate ecosystems and mineral soils while trampling effects on cold and organic matter‐rich tundra soils remain largely unknown. We aimed to develop a general model of trampling effects on soil structure, biota, microclimate and biogeochemical processes, with a particular focus on polar tundra soils. To reach this goal, we reviewed literature about the effects of trampling and physical disturbances on soils across biomes and used this to discuss the knowns and unknowns of trampling effects on tundra soils. We identified the following four pathways through which trampling affects soils: (a) soil compaction; (b) reductions in soil fauna and fungi; (c) rapid losses in vegetation biomass and cover; and (d) longer term shifts in vegetation community composition. We found that, in polar tundra, soil responses to trampling pathways 1 and 3 could be characterized by nonlinear dynamics and tundra‐specific context dependencies that we formulated into testable hypotheses. In conclusion, trampling may affect tundra soil significantly but many direct, interacting and cascading responses remain unknown. We call for research to advance the understanding of trampling effects on soils to support informed efforts to manage and predict the functioning of tundra systems under global changes.

• Bon, Matteo Petit; Inga, Katarina Gunnarsdotter; Jonsdottir, Ingibjørg; Utsi, Tove Aagnes; Soininen, Eeva M & Bråthen, Kari Anne (2020). Interactions between winter and summer herbivory affect spatial and temporal plant nutrient dynamics in tundra grassland communities. Oikos. ISSN 0030-1299. 129(8), p. 1229–1242. doi: 10.1111/oik.07074. Full text in Research Archive Show summary

  In the long‐term, herbivores can alter nutrient dynamics in terrestrial ecosystems by changing the functional composition of plant communities. Here, we ask to what extent herbivores can affect plant‐community nutrient dynamics in the short‐term. We provide theoretical expectations for immediate effects of herbivores on tundra‐grassland plant‐community nutrient levels throughout a single growing season and empirically evaluate these predictions. We established an experiment within two forb‐dominated and two grass‐dominated tundra‐grassland communities. We selected tundra‐patches disturbed by small rodents during the previous winter, and neighbouring undisturbed tundra‐patches. Within each tundra‐patch, we set up a reindeer‐open and a reindeer‐exclusion plot. Throughout the summer, we randomly collected over 2800 leaf samples from 34 vascular plant species/genera and analysed their nitrogen and phosphorus contents. Plant‐community nutrient levels were consistently higher in tundra‐patches affected by small rodents, both across tundra‐grassland types and throughout the growing season. Forbs and grasses growing in small‐rodent disturbed tundra‐patches had 11% and 25% higher nutrient content, respectively, compared to undisturbed tundra‐patches. Reindeer affected only grasses growing in grass‐dominated tundra‐grasslands and the outcome was dependent on small‐rodent winter disturbance. Reindeer increased grass nitrogen content in undisturbed tundra‐patches (+7%) and weakened the positive effects of small rodents in disturbed tundra‐patches (from 25% to 15% higher nutrient content [both nitrogen and phosphorus]). By enhancing plant nutrient levels throughout a single growing season, herbivores were key, immediate modifiers of plant‐community nutrient dynamics in tundra‐grasslands. Higher nutrient contents still detected in senescent leaves at the end of the summer in herbivore‐affected tundra suggest that herbivory is accelerating short‐term tundra‐grassland nutrient cycling rates. Our findings from tundra‐grassland communities align with theoretical expectations of positive herbivore effects on nutrient cycling in relatively productive ecosystems.

• Pilsbacher, Anna Katharina; Lindgård, Bente; Reiersen, Rigmor; Gonzalez, Victoria & Bråthen, Kari Anne (2020). Interfering with neighbouring communities: Allelopathy astray in the tundra delays seedling development. Functional Ecology. ISSN 0269-8463. 35(1), p. 266–276. doi: 10.1111/1365-2435.13694. Full text in Research Archive Show summary

  1. Altered species composition caused by environmental and climatic change can affect the transfer of plant residues among communities. Whereas transferred residues are typically considered a resource in recipient systems, residues of allelopathic species may instead cause interference. 2. Evergreen dwarf shrubs, specifically the allelopathic species Empetrum nigrum are increasing in abundance in response to a warming climate. Empetrum has small, evergreen leaves that can be transferred to other communities when withered and lost from the plant. 3. We hypothesize that Empetrum can have allelopathic effects in the recipient communities of the withered leaves. We call this allochthonous allelopathy as opposed to autochthonous allelopathy, which is well documented in communities where the plant grows. 4. We measured influx of allochthonous Empetrum leaves onto snow-covered snowbeds, where they are easily identified within the debris. Next, we compared the bioactivity of allochthonous withered leaves with that of green Empetrum leaves. Finally, we conducted an experiment testing the germination and seedling growth of 10 tundra species in snowbed soil supplemented with no (control) and three densities of allochthonous Empetrum leaves. 5. We found Empetrum leaves to be common on the snow cover of snowbeds. We found Empetrum leaves collected on snowbeds to be as bioactive as green leaves. Finally, we found forb species to have reduced germination and all 10 species to have delayed seedling development when growing in snowbed soil supplemented with withered Empetrum leaves. Seedlings under the control treatment were 2.3 times longer and had 3.2 times more leaves in comparison to seedlings grown under the strongest allochthonous leaf treatment. 6. Results from our study imply that Empetrum is allelopathic in recipient systems of its allochthonous leaves. The abundant nature of Empetrum in the tundra suggests that allochthonous allelopathy is a common phenomenon, causing biotic stress in snowbeds and potentially other parts of the tundra. Exemplifying the ability of a plant to interfere in neighbouring communities, our study demonstrates a plant trait that may provide insight to other study systems.

• Murguzur, Francisco Javier Ancin; Bison, Marjorie; Smis, Adriaan; Bohner, Hanna; Struyf, Eric & Meire, Patrick [Show all 7 contributors for this article] (2019). Towards a global arctic-alpine model for Near-infrared reflectance spectroscopy (NIRS) predictions of foliar nitrogen, phosphorus and carbon content. Scientific Reports. 9(1). doi: 10.1038/s41598-019-44558-9. Full text in Research Archive Show summary

  Near-infrared spectroscopy (NIRS) is a high-throughput technology with potential to infer nitrogen (N), phosphorus (P) and carbon (C) content of all vascular plants based on empirical calibrations with chemical analysis, but is currently limited to the sample populations upon which it is based. Here we provide a first step towards a global arctic-alpine NIRS model of foliar N, P and C content. We found calibration models to perform well (R2_validation = 0.94 and RMSEP = 0.20% for N, R2_validation = 0.76 and RMSEP = 0.05% for P and R2_validation = 0.82 and RMSEP = 1.16% for C), integrating 97 species, nine functional groups, three levels of phenology, a range of habitats and two biogeographic regions (the Alps and Fennoscandia). Furthermore, when applied for predicting foliar N, P and C content in samples from a new biogeographic region (Svalbard), our arctic-alpine NIRS model performed well. The precision of the resulting NIRS method meet international requirements, indicating one NIRS measurement scan of a foliar sample will predict its N, P and C content with precision according to standard method performance. The modelling scripts for the prediction of foliar N, P and C content using NIRS along with the calibration models upon which the predictions are based are provided. The modelling scripts can be applied in other labs, and can easily be expanded with data from new biogeographic regions of interest, building the global arctic-alpine model.

• O'Brien, Michael J; Menezes, Luis Fernando Tavares de; Bråthen, Kari Anne; Losapio, Gianalberto & Pugnaire, Francisco I. (2019). Facilitation mediates species presence beyond their environmental optimum. Perspectives in plant ecology, evolution and systematics. ISSN 1433-8319. 38, p. 24–30. doi: 10.1016/j.ppees.2019.03.004. Full text in Research Archive Show summary

  Species distributions are driven by abiotic conditions that filter species with specific traits and physiological tolerances and match them with their suitable environment. Plant–plant interactions can constrict (through competition) or loosen (through facilitation) the strength of these environmental filters, which in turn inhibit or enhance establishment and recruitment of plant species at a finer spatial scale. Although competition is often the focus of community assembly processes that further impede the entry of plant species into a site, facilitation is also important for potentially loosening environmental filters (especially climatic filters such as temperature and precipitation), ultimately enhancing species occurrence beyond their physiological optimum. We used multiple data sets from the arid site of Rambla del Saltador Valley to test the hypothesis that facilitation by a nurse-plant promotes the presence of herbaceous, beneficiary species beyond their environmental optimum relative to open sites. Furthermore, we propose that the median elevation and community composition of herbaceous species expands with the age of the nurse-plant, and we tested this hypothesis by examining 105 beneficiary species under 50 nurse-plant shrubs varying in age from 6 to 48 years old. We found nurse-plants both facilitate herbaceous species occurrence beyond their median elevation and support more diverse and a distinctly different composition of species in contrast to open sites. Specifically, herbaceous species that originate from a median elevation more than 600 to 700 m above the site only existed beneath nurse-plants, and below this median elevation, half the species only occurred below the nurse-plant. Moreover, the richness and elevation provenance of the herbaceous species increased with increasing nurse-plant age. Our results highlight the importance of facilitation for alleviating physiological strain (in support of the strain hypothesis) and mediating regional species distributions, which has implications for understanding species movements and community assembly at larger-scales under hotter and drier climates.

• Gonzalez, Victoria; Armendariz, Mikel Moriana; Hagen, Snorre; Lindgård, Bente; Reiersen, Rigmor & Bråthen, Kari Anne (2019). High resistance to climatic variability in a dominant tundra shrub species. PeerJ. 7. doi: 10.7717/peerj.6967. Full text in Research Archive Show summary

  Climate change is modifying temperature and precipitation regimes across all seasons in northern ecosystems. Summer temperatures are higher, growing seasons extend into spring and fall and snow cover conditions are more variable during winter. The resistance of dominant tundra species to these season-specific changes, with each season potentially having contrasting effects on their growth and survival, can determine the future of tundra plant communities under climate change. In our study, we evaluated the effects of several spring/summer and winter climatic variables (i.e., summer temperature, growing season length, growing degree days, and number of winter freezing days) on the resistance of the dwarf shrub Empetrum nigrum. We measured over six years the ability of E. nigrum to keep a stable shoot growth, berry production, and vegetative cover in five E. nigrum dominated tundra heathlands, in a total of 144 plots covering a 200-km gradient from oceanic to continental climate. Overall, E. nigrum displayed high resistance to climatic variation along the gradient, with positive growth and reproductive output during all years and sites. Climatic conditions varied sharply among sites, especially during the winter months, finding that exposure to freezing temperatures during winter was correlated with reduced shoot length and berry production. These negative effects however, could be compensated if the following growing season was warm and long. Our study demonstrates that E. nigrum is a species resistant to fluctuating climatic conditions during the growing season and winter months in both oceanic and continental areas. Overall, E. nigrum appeared frost hardy and its resistance was determined by interactions among different season-specific climatic conditions with contrasting effects.

• Bråthen, Kari Anne; Gonzalez, Victoria & Yoccoz, Nigel Gilles (2018). Gatekeepers to the effects of climate warming? Niche construction restricts plant community changes along a temperature gradient. Perspectives in plant ecology, evolution and systematics. ISSN 1433-8319. 30, p. 71–81. doi: 10.1016/j.ppees.2017.06.005. Full text in Research Archive Show summary

  Organisms that modify the environment (niche constructors) are likely candidates to mediate the effects of climate warming. Here we assess tundra plant community changes along a temperature gradient and how these are modified in the presence of the common allelopathic dwarf shrub Empetrum nigrum and the large herbivore Rangifer tarandus. We developed a structural equation model based on data from a field-based study of 1450 tundra plant communities across Northern Fennoscandia, covering a temperature gradient of 3.5 °C, contrasting Rangifer densities, a range of Empetrum abundances in addition to gradients in topography and bedrock. We found temperature to be a significant positive predictor of Empetrum, herbaceous and woody plant abundances. However, the effect of temperature as predictor for herbaceous plant abundance was significantly reduced in communities with Empetrum present. For woody plant abundance Empetrum was a stronger predictor than temperature. In comparison, we found Rangifer density to have marginal or no effect on either herbaceous or woody plant abundance. These findings were not modified by either topography or bedrock. Results from this study indicate that herbaceous plant responses to climate warming are currently reduced in communities where Empetrum is present, whereas the abundance of Empetrum and other woody plants is promoted. Results also indicate that any future Empetrum encroachment is likely to drive tundra communities towards slower process rates and lower biodiversity. As such our results substantiate the importance of understanding the dynamics of niche constructor species and include them in predictive models of climate change.

• Soininen, Eeva M; Henden, John-André; Ravolainen, Virve; Yoccoz, Nigel Gilles; Bråthen, Kari Anne & Killengreen, Siw Turid [Show all 7 contributors for this article] (2018). Transferability of biotic interactions: temporal consistency of arctic plant-rodent relationships is poor. Ecology and Evolution. 8, p. 9697–9711. doi: 10.1002/ece3.4399. Full text in Research Archive Show summary

  Variability in biotic interaction strength is an integral part of food web functioning. However, the consequences of the spatial and temporal variability of biotic interactions are poorly known, in particular for predicting species abundance and distribution. The amplitude of rodent population cycles (i.e., peak-phase abundances) has been hypothesized to be determined by vegetation properties in tundra ecosystems. We assessed the spatial and temporal predictability of food and shelter plants effects on peak-phase small rodent abundance during two consecutive rodent population peaks. Rodent abundance was related to both food and shelter biomass during the first peak, and spatial transferability was mostly good. Yet, the temporal transferability of our models to the next population peak was poorer. Plant–rodent interactions are thus temporally variable and likely more complex than simple one-directional (bottom-up) relationships or variably overruled by other biotic interactions and abiotic factors. We propose that parametrizing a more complete set of functional links within food webs across abiotic and biotic contexts would improve transferability of biotic interaction models. Such attempts are currently constrained by the lack of data with replicated estimates of key players in food webs. Enhanced collaboration between researchers whose main research interests lay in different parts of the food web could ameliorate this.

• Tuomi, Maria Wilhelmina; Stark, Sari; Hoset, Katrine Skamfer; Väisänen, Maria; Oksanen, Lauri & Murguzur, Francisco Javier Ancin [Show all 9 contributors for this article] (2018). Herbivore Effects on Ecosystem Process Rates in a Low-Productive System. Ecosystems. ISSN 1432-9840. p. 1–17. doi: 10.1007/s10021-018-0307-4. Full text in Research Archive Show summary

  Mammalian herbivores shape the structure and function of many nutrient-limited or low-productive terrestrial ecosystems through modification of plant communities and plant–soil feedbacks. In the tundra biome, mammalian herbivores may both accelerate and decelerate plant biomass growth, microbial activity and nutrient cycling, that is, ecosystem process rates. Selective foraging and associated declines of palatable species are known to be major drivers of plant–soil feedbacks. However, declines in dominant plants of low palatability often linked with high herbivore densities may also modify ecosystem process rates, yet have received little attention. We present data from an island experiment with a 10-year vole density manipulation, to test the hypothesis that herbivores accelerate process rates by decreasing the relative abundance of poorly palatable plants to palatable ones. We measured plant species abundances and community composition, nitrogen contents of green plant tissues and multiple soil and litter variables under high and low vole density. Corroborating our hypothesis, periodic high vole density increased ecosystem process rates in lowproductive tundra. High vole density was associated with both increasing relative abundance of palatable forbs over unpalatable evergreen dwarf shrubs and higher plant N content both at species and at community level. Changes in plant community composition, in turn, explained variation in microbial activity in litter and soil inorganic nutrient availability. We propose a new conceptual model with two distinct vole–plant–soil feedback pathways. Voles may drive local plant–soil feedbacks that either increase or decrease ecosystem process rates, in turn promoting heterogeneity in vegetation and soils across tundra landscapes.

• Clarke, Charlotte; Edwards, Mary Elizabeth; Brown, Antony Gavin; Gielly, Ludovic; Lammers, Youri & Heintzman, Peter D. [Show all 10 contributors for this article] (2018). Holocene floristic diversity and richness in northeast Norway revealed by sedimentary ancient DNA (sedaDNA) and pollen. Boreas. ISSN 0300-9483. p. 1–18. doi: 10.1111/bor.12357. Full text in Research Archive Show summary

  We present a Holocene record of floristic diversity and environmental change for the central Varanger Peninsula, Finnmark, based on ancient DNA extracted from the sediments of a small lake (<i>sed</i>aDNA). The record covers the period c. 10 700 to 3300 cal. a BP and is complemented by pollen data. Measures of species richness, sample evenness and beta diversity were calculated based on <i>sed</i>aDNA sampling intervals and 1000‐year time windows. We identified 101 vascular plant and 17 bryophyte taxa, a high proportion (86%) of which are still growing within the region today. The high species richness (>60 taxa) observed in the Early Holocene, including representatives from all important plant functional groups, shows that modern shrub‐tundra communities, and much of their species complement, were in place as early as c. 10 700 cal. a BP. We infer that postglacial colonization of the area occurred prior to the full Holocene, during the Pleistocene‐Holocene transition, Younger Dryas stadial or earlier. Abundant DNA of the extra‐limital aquatic plant <i>Callitriche hermaphroditica</i> suggests it expanded its range northward between c. 10 200 and 9600 cal. a BP, when summers were warmer than present. High values of <i>Pinus</i> DNA occur throughout the record, but we cannot say with certainty if they represent prior local presence; however, pollen influx values >500 grains cm⁻² a⁻¹ between c. 8000 and 7300 cal. a BP strongly suggest the presence of pine woodland during this period. As the site lies beyond the modern tree limit of pine, it is likely that this expansion also reflects a response to warmer Early Holocene summers.

• Graae, Bente Jessen; Vandvik, Vigdis; Armbruster, W. Scott; Eiserhardt, Wolf L.; Svenning, Jens-Christian & Hylander, Kristoffer [Show all 19 contributors for this article] (2017). Stay or go - how topographic complexity influences alpine plant population and community responses to climate change. Perspectives in plant ecology, evolution and systematics. ISSN 1433-8319. 30, p. 41–50. doi: 10.1016/j.ppees.2017.09.008. Full text in Research Archive Show summary

  In the face of climate change, populations have two survival options − they can remain in situ and tolerate the new climatic conditions (“stay”), or they can move to track their climatic niches (“go”). For sessile and small-stature organisms like alpine plants, staying requires broad climatic tolerances, realized niche shifts due to changing biotic interactions, acclimation through plasticity, or rapid genetic adaptation. Going, in contrast, requires good dispersal and colonization capacities. Neither the magnitude of climate change experienced locally nor the capacities required for staying/going in response to climate change are constant across landscapes, and both aspects may be strongly affected by local microclimatic variation associated with topographic complexity. We combine ideas from population and community ecology to discuss the effects of topographic complexity in the landscape on the immediate “stay” or “go” opportunities of local populations and communities, and on the selective pressures that may have shaped the stay or go capacities of the species occupying contrasting landscapes. We demonstrate, using example landscapes of different topographical complexity, how species’ thermal niches could be distributed across these landscapes, and how these, in turn, may affect many population and community ecological processes that are related to adaptation or dispersal. Focusing on treeless alpine or Arctic landscapes, where temperature is expected to be a strong determinant, our theorethical framework leads to the hypothesis that populations and communities of topographically complex (rough and patchy) landscapes should be both more resistant and more resilient to climate change than those of topographically simple (flat and homogeneous) landscapes. Our theorethical framework further points to how meta-community dynamics such as mass effects in topographically complex landscapes and extinction lags in simple landscapes, may mask and delay the long-term outcomes of these landscape differences under rapidly changing climates.

• Barrio, Isabel C.; Lindén, Elin; Beest, Mariska te; Olofsson, Johan; Rocha, Adrian & Soininen, Eeva M [Show all 60 contributors for this article] (2017). Background invertebrate herbivory on dwarf birch (Betula glandulosa-nana complex) increases with temperature and precipitation across the tundra biome. Polar Biology. ISSN 0722-4060. 40(11), p. 2265–2278. doi: 10.1007/s00300-017-2139-7. Full text in Research Archive Show summary

  Chronic, low intensity herbivory by invertebrates, termed background herbivory, has been understudied in tundra, yet its impacts are likely to increase in a warmer Arctic. The magnitude of these changes is however hard to predict as we know little about the drivers of current levels of invertebrate herbivory in tundra. We assessed the intensity of invertebrate herbivory on a common tundra plant, the dwarf birch (Betula glandulosa-nana complex), and investigated its relationship to latitude and climate across the tundra biome. Leaf damage by defoliating, mining and gall-forming invertebrates was measured in samples collected from 192 sites at 56 locations. Our results indicate that invertebrate herbivory is nearly ubiquitous across the tundra biome but occurs at low intensity. On average, invertebrates damaged 11.2% of the leaves and removed 1.4% of total leaf area. The damage was mainly caused by external leaf feeders, and most damaged leaves were only slightly affected (12% leaf area lost). Foliar damage was consistently positively correlated with mid-summer (July) temperature and, to a lesser extent, precipitation in the year of data collection, irrespective of latitude. Our models predict that, on average, foliar losses to invertebrates on dwarf birch are likely to increase by 6–7% over the current levels with a 1 °C increase in summer temperatures. Our results show that invertebrate herbivory on dwarf birch is small in magnitude but given its prevalence and dependence on climatic variables, background invertebrate herbivory should be included in predictions of climate change impacts on tundra ecosystems.

• Loison, Anne; Paye, Simon; Schermann, Agnes; Bry, Clementine; Gaillard, Jean-Michel & Pelabon, Christophe [Show all 7 contributors for this article] (2017). The domestic basis of the scientific career: gender inequalities in ecology in France and Norway. European Educational Research Journal. 16(2-3), p. 230–257. doi: 10.1177/1474904116672469. Full text in Research Archive Show summary

  Gender-related inequalities in scientific careers are widespread, evidenced by the attrition of women along the different stages of the promotion ladder. We studied the interwoven personal and professional trajectories of researchers in ecology and compared these trajectories between welfare state policies and work/family regimes, we expected contrasts in the depth and modalities of the gender gap. We focused on the career consequences of time-use inequalities in the workplace and in the private sphere (domestic tasks and parental care). We find a more frequent assignment of women to less-valued tasks at work (e.g. teaching) and pronounced gender differences in the involvement in domestic and parental tasks, especially in France. Age at promotion and probability to be promoted differed between gender in both countries and more so in France, women being less promoted and promoted later than men. This gender gap was particularly discriminating women with children, when they were either single or with a partner who also was a researcher. These differences are mainly due to a lower scientific productivity of women when they get children. These analyses raise a number of questions on welfare policies and on the definition of academic standards of peer judgment within local employment policies in universities.

• Moodie, Lindon; Trepos, Rozenn; Cervin, Gunnar; Bråthen, Kari Anne; LindgÅrd, bente & Reiersen, rigmor [Show all 10 contributors for this article] (2017). Prevention of Marine Biofouling Using the Natural Allelopathic Compound Batatasin-III and Synthetic Analogues. Journal of natural products. ISSN 0163-3864. 80(7), p. 2001–2011. doi: 10.1021/acs.jnatprod.7b00129. Full text in Research Archive Show summary

  The current study reports the first comprehensive evaluation of a class of allelopathic terrestrial natural products as antifoulants in a marine setting. To investigate the antifouling potential of the natural dihydrostilbene scaffold, a library of 22 synthetic dihydrostilbenes with varying substitution patterns, many of which occur naturally in terrestrial plants, were prepared and assessed for their antifouling capacity. The compounds were evaluated in an extensive screen against 16 fouling marine organisms. The dihydrostilbene scaffold was shown to possess powerful general antifouling effects against both marine microfoulers and macrofoulers with inhibitory activities at low concentrations. The species of microalgae examined displayed a particular sensitivity toward the evaluated compounds at low ng/mL concentrations. It was shown that several of the natural and synthetic compounds exerted their repelling activities via nontoxic and reversible mechanisms. The activities of the most active compounds such as 3,5-dimethoxybibenzyl (5), 3,4-dimethoxybibenzyl (9), and 3-hydroxy-3′,4,5′-trimethoxybibenzyl (20) were comparable to the commercial antifouling booster biocide Sea-nine, which was employed as a positive control. The investigation of terrestrial allelopathic natural products to counter marine fouling represents a novel strategy for the design of “green” antifouling technologies, and these compounds offer a potential alternative to traditional biocidal antifoulants.

• Bråthen, Kari Anne; Ravolainen, Virve; Stien, Audun; Tveraa, Torkild & Ims, Rolf Anker (2017). Rangifer management controls a climate-sensitive tundra state transition. Ecological Applications. ISSN 1051-0761. 27(8), p. 2416–2427. doi: 10.1002/eap.1618. Full text in Research Archive Show summary

  Rangifer (caribou/reindeer) management has been suggested to mitigate the temperature- driven transition of Arctic tundra into a shrubland state, yet how this happens is uncertain. Here we study this much focused ecosystem state transition in riparian areas, where palatable willows (Salix) are dominant tall shrubs and highly responsive to climate change. For the state transition to take place, small life stages must become tall and abundant. Therefore we predicted that the performance of small life stages (potential recruits) of the tall shrubs were instrumental to the focal transition, where Rangifer managed at high population density would keep the small-stage shrubs in a “browse trap” independent of summer temperature. We used a large-scale quasi-experimental study design that included real management units that spanned a wide range of Rangifer population densities and summer temperatures in order to assess the relative importance of these two driving variables. Ground surveys provided data on density and height of the small shrub life stages, while the distributional limit (shrubline) of established shrublands (the tall shrub life stage) was derived from aerial photographs. Where Rangifer densities were above a threshold of approximately 5 animals/km2, we found, in accordance with the expectation of a “browse trap,” that the small life stages of shrubs in grasslands were at low height and low abundance. At Rangifer densities below this threshold, the small life stages of shrubs were taller and more abundant indicating Rangifer were no longer in control of the grassland state. For the established shrubland state, we found that the shrubline was at a 100- m lower elevation in the management units where Rangifer had been browsing in summer as opposed to the migratory ranges with no browsing in summer. In both seasonal ranges, the shrubline increased 100 m per 1°C increment in temperature. Our study supports the proposal that Rangifer management within a sustainable range of animal densities can mitigate the much-focused transition from grassland to shrubland in a warming Arctic. browse trap; browsing; climate change; life history stage; plant–herbivore interactions; Salix; shrub growth; shrubline; summer temperature.

• Gjørv, Gunhild Hoogensen; Dale, Brigt; Lvova, Maria; Bråthen, Kari Anne; Gonzalez, Victoria & Bazely, Dawn [Show all 9 contributors for this article] (2016). Human Security in the Arctic: The IPY GAPS Project. From Pole to Pole. ISSN 2193-7338. p. 181–201. doi: 10.1007/978-3-642-12315-3_10. Full text in Research Archive
• Tirado, Reyes; Bråthen, Kari Anne & Pugnaire, Francisco (2015). Mutual positive effects between shrubs in an arid ecosystem. Scientific Reports. 5. doi: 10.1038/srep14710. Full text in Research Archive Show summary

  One-way facilitation in plants has been found in many harsh environments and their role as structural forces governing species composition in plant communities is now well established. However, reciprocal positive effects benefiting two interacting species have seldom been reported and, in recent reviews, conceptually considered merely as facilitation when in fact there is room for adaptive strategies and evolutionary responses. We tested the existence of such reciprocal positive effects in an arid environment in SE Spain using spatial pattern analysis, a species removal experiment, and a natural experiment. We found that the spatial association between Maytenus senegalensis and Whitania frutescens, two shrub species of roughly similar size intimately interacting in our community, resulted in mutual benefit for both species. Benefits included improved water relations and nutritional status and protection against browsing, and did occur despite simultaneous competition for resources. Our data suggest two-way facilitation or, rather, a facultative mutualism among higher plant species, a process often overlooked which could be a main driver of plant community dynamics allowing for evolutionary processes.

• Wasof, Safaa; Lenoir, Jonathan; Aarrestad, Per Arild; Alsos, Inger Greve; Armbruster, W. Scott & Austrheim, Gunnar [Show all 48 contributors for this article] (2015). Disjunct populations of European vascular plant species keep the same climatic niches. Global Ecology and Biogeography. ISSN 1466-822X. 24(12), p. 1401–1412. doi: 10.1111/geb.12375. Full text in Research Archive Show summary

  Aim Previous research on how climatic niches vary across species ranges has focused on a limited number of species, mostly inv asive, and has not, to date, been very conclusive. Here we assess the degree of niche conservatism between distant populations of native alpine plant species that have been separated for thousands of years. Location European Alps and Fennoscandia. Methods Of the studied pool of 888 terrestr ial vascular plant species occurring in both the Alps and Fennoscandia, we used two complementary approaches to test and quantify climatic-niche shifts for 31 species having strictly disjunct populations and 358 species having either a contiguous or a patchy distribution with distant populations. First, we used species distr i- bution modelling to test for a region effect on each species’ climatic niche. Second, we quantified niche overlap and shifts in niche width (i.e. ecological amplitude) and position (i.e. ecological optimum) within a bi-dimensional climatic space. Results Only one species (3%) of the 31 species with str ictly disjunct populations and 58 species (16%) of the 358 species with distant popula- tions showed a region effect on their climatic niche. Niche overlap was higher for species with strictly disjunct populations than for species with distant populations and highest for arctic–alpine species. Climatic niches were, on average, wider and located towards warmer and wetter conditions in the Alps. Main conclusion Climatic niches seem to be generally conserved between populations that are separated between the Alps and Fennoscandia and have probably been so for 10,000–15,000 years. Therefore, the basic assumption of species distribution models that a species’ climatic niche is constant in space and time – at least on time scales 10 4 years or less – seems to be largely valid for arctic–alpine plants.

• Jansson, Roland; Nilsson, Christer; Keskitalo, E. Carina H.; Viasova, Tatiana; Sutinen, Marja-Liisa & Moen, Jon [Show all 15 contributors for this article] (2015). Future changes in the supply of goods and services from natural ecosystems: prospects for the European north. Ecology & Society. 20(3). doi: 10.5751/ES-07607-200332. Full text in Research Archive Show summary

  Humans depend on services provided by ecosystems, and how services are affected by climate change is increasingly studied. Few studies, however, address changes likely to affect services from seminatural ecosystems. We analyzed ecosystem goods and services in natural and seminatural systems, specifically how they are expected to change as a result of projected climate change during the 21st century. We selected terrestrial and freshwater systems in northernmost Europe, where climate is anticipated to change more than the global average, and identified likely changes in ecosystem services and their societal consequences. We did this by assembling experts from ecology, social science, and cultural geography in workshops, and we also performed a literature review. Results show that most ecosystem services are affected by multiple factors, often acting in opposite directions. Out of 14 services considered, 8 are expected to increase or remain relatively unchanged in supply, and 6 are expected to decrease. Although we do not predict collapse or disappearance of any of the investigated services, the effects of climate change in conjunction with potential economical and societal changes may exceed the adaptive capacity of societies. This may result in societal reorganization and changes in ways that ecosystems are used. Significant uncertainties and knowledge gaps in the forecast make specific conclusions about societal responses to safeguard human well-being questionable. Adapting to changes in ecosystem services will therefore require consideration of uncertainties and complexities in both social and ecological responses. The scenarios presented here provide a framework for future studies exploring such issues.

• Gonzalez, Victoria; Junttila, Olavi; LindgÅrd, bente; Reiersen, rigmor; Trost, Kajetan & Bråthen, Kari Anne (2015). Batatasin-III and the allelopathic capacity of Empetrum nigrum. Nordic Journal of Botany (NJB). ISSN 0107-055X. 33(2), p. 225–231. doi: 10.1111/njb.00559. Full text in Research Archive
• Bråthen, Kari Anne & Ravolainen, Virve (2015). Niche construction by growth forms is as strong a predictor of species diversity as environmental gradients. Journal of Ecology. ISSN 0022-0477. 103(3), p. 701–713. doi: 10.1111/1365-2745.12380. Full text in Research Archive
• Bråthen, Kari Anne & Lortie, Christopher (2015). A portfolio effect of shrub canopy height on species richness in both stressful and competitive environments. Functional Ecology. ISSN 0269-8463. doi: 10.1111/1365-2435.12458. Full text in Research Archive
• Bernes, Claes; Bråthen, Kari Anne; Forbes, Bruce C.; Speed, James David Mervyn & Moen, Jon (2015). What are the impacts of reindeer/caribou (Rangifer tarandus L.) on arctic and alpine vegetation? A systematic review. Environmental Evidence. 4:4. doi: 10.1186/s13750-014-0030-3. Full text in Research Archive Show summary

  Background:The reindeer (or caribou,Rangifer tarandusL.) has a natural range extending over much of Eurasia’s and North America’s arctic, alpine and boreal zones, yet its impact on vegetation is still unclear. This lack of a common understanding hampers both the management of wild and semi-domesticated reindeer populations and the preservation of biodiversity. To achieve a common platform, we have undertaken a systematic review of published studies that compare vegetation at sites with different reindeer densities. Besides biodiversity, we focused on effects on major plant growth forms. Methods:Searches for literature were made using online publication databases, search engines, specialist websites and bibliographies of literature reviews. Search terms were developed in English, Finnish, Norwegian, Russian and Swedish. Identified articles were screened for relevance based on titles, abstracts and full text using inclusion criteria set out in ana prioriprotocol. Relevant articles were then subject to critical appraisal of susceptibility to bias. Data on outcomes such as abundance, biomass, cover and species richness of vegetation were extracted together with metadata on site properties and other potential effect modifiers. Results:Our searches identified more than 6,000 articles. After screening for relevance, 100 of them remained. Critical appraisal excluded 60 articles, leaving 40 articles with 41 independent studies. Almost two thirds of these studies had been conducted in Fennoscandia. Meta-analysis could be made of data from 31 of the studies. Overall, effects of reindeer on species richness of vascular plants depended on temperature, ranging from negative at low temperature to positive at high temperature. Effects on forbs, graminoids, woody species, and bryophytes were weak or non-significant, whereas the effect on lichens was negative. However, many individual studies showed clear positive or negative effects, but the available information was insufficient to explain this context dependence. Conclusions:We see two pressing matters emerging from our study. First, there is a lack of research with which to build a circumpolar understanding of grazing effects, which calls for more studies using a common protocol to quantify reindeer impacts. Secondly, the highly context-dependent outcomes suggest that research and management have to consider local conditions. For instance, predictions of what a management decision would mean for the effects of reindeer on vegetation will have to take the variation of vegetation types and dominant growth forms, productivity, and grazing history into account. Policy and management have to go hand-in-hand with research in individual cases if the dynamics between plants, animals, and humans are to be sufficiently understood. Keywords:Reindeer, Caribou,Rangifer tarandus, Forbs, Grasses, Graminoids, Woody species, Lichens, Bryophytes, Species diversity, Herbivory, Grazing, Browsing, Tundra

• Mörsdorf, Martin Alfons; Ravolainen, Virve; Støvern, Einar; Yoccoz, Nigel Gilles; Jonsdottir, Ingibjørg & Bråthen, Kari Anne (2015). Definition of sampling units begets conclusions in ecology: The case of habitats for plant communities. PeerJ. 2015(3). doi: 10.7717/peerj.815. Full text in Research Archive Show summary

  In ecology, expert knowledge on habitat characteristics is often used to define sampling units such as study sites. Ecologists are especially prone to such approaches when prior sampling frames are not accessible. Here we ask to what extent can different approaches to the definition of sampling units influence the conclusions that are drawn from an ecological study? We do this by comparing a formal versus a subjective definition of sampling units within a study design which is based on well-articulated objectives and proper methodology. Both approaches are applied to tundra plant communities in mesic and snowbed habitats. For the formal approach, sampling units were first defined for each habitat in concave terrain of suitable slope using GIS. In the field, these units were only accepted as the targeted habitats if additional criteria for vegetation cover were fulfilled. For the subjective approach, sampling units were defined visually in the field, based on typical plant communities of mesic and snowbed habitats. For each approach, we collected information about plant community characteristics within a total of 11 mesic and seven snowbed units distributed between two herding districts of contrasting reindeer density. Results from the two approaches differed significantly in several plant community characteristics in both mesic and snowbed habitats. Furthermore, differences between the two approaches were not consistent because their magnitude and direction differed both between the two habitats and the two reindeer herding districts. Consequently, we could draw different conclusions on how plant diversity and relative abundance of functional groups are differentiated between the two habitats depending on the approach used. We therefore challenge ecologists to formalize the expert knowledge applied to define sampling units through a set of well-articulated rules, rather than applying it subjectively. We see this as instrumental for progress in ecology as only rules based on expert knowledge are transparent and lead to results reproducible by other ecologists.

• Bråthen, Kari Anne; Jahiri, Xhevahire; Jusdado, Juan German Herranz; Soininen, Eeva M & Jensen, John Beck (2015). Fungal endophyte diversity in tundra grasses increases by grazing. Fungal ecology. ISSN 1754-5048. 17, p. 41–51. doi: 10.1016/j.funeco.2015.05.002. Full text in Research Archive
• Ravolainen, Virve; Bråthen, Kari Anne; Yoccoz, Nigel; Kollstrøm, Julie Orvik & Ims, Rolf Anker (2014). Complementary impacts of small rodents and semi-domesticated ungulates limit tall shrub expansion in the tundra. Journal of Applied Ecology. ISSN 0021-8901. 51(1), p. 234–241. doi: 10.1111/1365-2664.12180. Full text in Research Archive
• Willerslev, E; Davison, J; Moora, M; Zobel, M; Coissac, E & Edwards, ME [Show all 50 contributors for this article] (2014). Fifty thousand years of Arctic vegetation and megafaunal diet. Nature. ISSN 0028-0836. 506(7486), p. 47–51. doi: 10.1038/nature12921. Full text in Research Archive
• Iversen, Marianne; Fauchald, Per; Langeland, Knut; Ims, Rolf Anker; Yoccoz, Nigel Gilles & Bråthen, Kari Anne (2014). Phenology and cover of plant growth forms predict herbivore habitat selection in a high latitude ecosystem. PLOS ONE. 9(6). doi: 10.1371/journal.pone.0100780. Full text in Research Archive Show summary

  The spatial and temporal distribution of forage quality is among the most central factors affecting herbivore habitat selection. Yet, for high latitude areas, forage quantity has been found to be more important than quality. Studies on large ungulate foraging patterns are faced with methodological challenges in both assessing animal movements at the scale of forage distribution, and in assessing forage quality with relevant metrics. Here we use first-passage time analyses to assess how reindeer movements relate to forage quality and quantity measured as the phenology and cover of growth forms along reindeer tracks. The study was conducted in a high latitude ecosystem dominated by low-palatable growth forms. We found that the scale of reindeer movement was season dependent, with more extensive area use as the summer season advanced. Small-scale movement in the early season was related to selection for younger stages of phenology and for higher abundances of generally phenologically advanced palatable growth forms (grasses and deciduous shrubs). Also there was a clear selection for later phenological stages of the most dominant, yet generally phenologically slow and lowpalatable growth form (evergreen shrubs). As the summer season advanced only quantity was important, with selection for higher quantities of one palatable growth form and avoidance of a low palatable growth form. We conclude that both forage quality and quantity are significant predictors to habitat selection by a large herbivore at high latitude. The early season selectivity reflected that among dominating low palatability growth forms there were palatable phenological stages and palatable growth forms available, causing herbivores to be selective in their habitat use. The diminishing selectivity and the increasing scale of movement as the season developed suggest a response by reindeer to homogenized forage availability of low quality.

• Smis, Adriaan; Murguzur, Francisco Javier Ancin; Struyf, Eric; Soininen, Eeva M; Herranz, Jusdado Juan G & Meire, Patrick [Show all 7 contributors for this article] (2014). Determination of plant silicon content with near infrared reflectance spectroscopy. Frontiers in Plant Science. 5. doi: 10.3389/fpls.2014.00496. Full text in Research Archive
• Ims, Rolf Anker; Ehrich, Dorothee; Forbes, Bruce C.; Huntley, Brian; Walker, Donald A. & Wookey, Philip A. [Show all 25 contributors for this article] (2013). Terrestrial Ecosystems. In Meltofte, Hans (Eds.), Arctic Biodiversity Assessment. Status and trends in arctic biodiversity. Conservation of arctic flora and fauna. ISSN 9789935431226. p. 384–440. Full text in Research Archive
• Lenoir, Jonathan; Graae, Bente Jessen; Aarrestad, Per Arild; Alsos, Inger Greve; Armbruster, William Scott & Austrheim, Gunnar [Show all 35 contributors for this article] (2013). Local temperatures inferred from plant communities suggest strong spatial buffering of climate warming across Northern Europe. Global Change Biology. ISSN 1354-1013. 19(5), p. 1470–1481. doi: 10.1111/gcb.12129. Full text in Research Archive Show summary

  Recent studies from mountainous areas of small spatial extent (<2,500 km2) suggest that fine-grained thermal variability over tens or hundreds of metres exceeds much of the climate warming expected for the coming decades. Such variability in temperature provides buffering to mitigate climate-change impacts. Is this local spatial buffering restricted to topographically complex terrains? To answer this, we here study fine-grained thermal variability across a 2,500-km wide latitudinal gradient in Northern Europe encompassing a large array of topographic complexities. We first combined plant community data, Ellenberg temperature indicator values, locally measured temperatures (LmT), and globally interpolated temperatures (GiT) in a modelling framework to infer biologically relevant temperature conditions from plant assemblages within <1,000-m2 units (community-inferred temperatures: CiT). We then assessed: (1) CiT range (thermal variability) within 1-km2 units; (2) the relationship between CiT range and topographically- and geographically-derived predictors at 1-km resolution; and (3) whether spatial turnover in CiT is greater than spatial turnover in GiT within 100-km2 units. Ellenberg temperature indicator values in combination with plant assemblages explained 46-72% of variation in LmT and 92-96% of variation in GiT during the growing season (June, July, August). Growing-season CiT range within 1-km2 units peaked at 60-65°N and increased with terrain roughness, averaging 1.97°C (SD = 0.84°C) and 2.68°C (SD = 1.26°C) within the flattest and roughest units, respectively. Complex interactions between topography-related variables and latitude explained 35% of variation in growing-season CiT range when accounting for sampling effort and residual spatial autocorrelation. Spatial turnover in growing-season CiT within 100-km2 units was, on average, 1.8 times greater (0.32°C km-1) than spatial turnover in growing-season GiT (0.18°C km-1). We conclude that thermal variability within 1-km2 units strongly increases local spatial buffering of future climate warming across Northern Europe, even in the flattest terrains.

• Bernes, Claes; Bråthen, Kari Anne; Forbes, Bruce C.; Hofgaard, Annika; Moen, Jon & Speed, James David Mervyn (2013). What are the impacts of reindeer/caribou (Rangifer tarandus L.) on arctic and alpine vegetation? A systematic review protocol. Environmental Evidence. 2. doi: 10.1186/2047-2382-2-6. Full text in Research Archive Show summary

  Abstract Background: Reindeer and caribou (both belonging to the species Rangifer tarandus L.) are among the most important large herbivores in Eurasia’s and North America’s arctic, alpine and boreal zones. In Sweden, the impact of reindeer grazing on arctic and alpine vegetation has recently been re-evaluated. In the 1990s, records of grazing-related vegetation degradation helped to form a widespread perception that some mountain areas were overgrazed. However, later analyses have shown no evidence of large-scale overutilisation of reindeer ranges in the Swedish mountains. The present-day consensus is that overgrazing has been temporary and local, and that it rarely has caused permanent damage, but it is imperative to examine the scientific support for these views. Moreover, the Swedish Parliament has adopted an environmental quality objective according to which it is essential to preserve ‘a mountain landscape characterised by grazing’. No details have been given on how this goal is to be interpreted, which is another reason why the significance of reindeer grazing for arctic/alpine vegetation needs to be assessed. This protocol presents the methodology that will be used in a systematic review of the impact of reindeer herbivory in arctic and alpine ecosystems. The focus will be on Fennoscandia, but data from other parts of the range of R. tarandus will be used when deemed appropriate. Methods: The review will be based on primary field studies that compare vegetation subject to different degrees of reindeer/caribou herbivory (including grazing and browsing as well as trampling). Such comparisons can be either temporal, spatial or both. The review will cover impacts of herbivory in arctic, subarctic, alpine and subalpine areas (including the forest-tundra ecotone) across the range of R. tarandus, but not in boreal forests. Relevant aspects of vegetation include cover (abundance), biomass, diversity (e.g. species richness), structure, composition (including functional groups) and productivity. Keywords: Reindeer, Caribou, Rangifer tarandus, Herbivory, Grazing, Browsing, Vegetation, Alpine, Arctic, Tundra

View all works in NVA

• Soininen, Eeva M; Paulsen, Ingrid Marie Garfelt; Bråthen, Kari Anne; Eikeland, Oline; Kleiven, Eivind Flittie & Ravolainen, Virve (2025). Teknologi gir nye muligheter, hvordan ta den i bruk på tundraen? Ottar. ISSN 0030-6703. 71(2), p. 11–18. doi: 10.7557/ottar.8446. Full text in Research Archive Show summary

  Teknologi har åpnet nye dører for terrestrisk overvåking som kan hjelpe å besvare nye og gamle spørsmål om det økologiske samspillet på tundraen. Men med nye muligheter følger også nye utfordringer. Hvordan tilpasser vi teknologi til ekstreme klimaforhold? Og hvordan sikrer vi at dataene vi samler inn er pålitelige og anvendelige?

• Monteux, Sylvain; Blume-Werry, Gesche; Bokhorst, Stef; Bråthen, Kari Anne; Cooper, Elisabeth & Coulson, Stephen James [Show all 28 contributors for this article] (2024). Introducing the Circum-Arctic Present and Future Ecology of the Soil Food Web Group. Verhandlungen der Gesellschaft für Ökologie. ISSN 0171-1113. Full text in Research Archive
• Kiilunen, Petteri; Maliniemi, Tuija; Alahuhta, Janne; Grytnes, John Arvid; Bråthen, Kari Anne & Happonen, Konsta [Show all 11 contributors for this article] (2022). Temporal changes in pollination ecosystem service in high-latitude environments. Full text in Research Archive
• Utsi, Tove Aagnes; Yoccoz, Nigel; Armstrong, Claire; Gonzalez, Victoria; Hagen, Snorre & Jónsdóttir, Ingibjörg Svala [Show all 12 contributors for this article] (2021). Evergreening of the tundra – blindspot in the management of a social-ecological system? Full text in Research Archive
• Bråthen, Kari Anne; Gulden, Kathrine Torday & Gonzalez, Victoria (2021). Krekling kan ødelegge utmark. [Journal]. Nationen. Full text in Research Archive
• Bråthen, Kari Anne (2021). Utvikling i økosystemets primærproduksjon. Full text in Research Archive
• Alsos, Inger Greve; Heintzman, Peter D.; Rijal, Dilli Prasad; Brown, Antony; Clarke, Charlotte L. & Bjune, Anne Elisabeth [Show all 24 contributors for this article] (2020). Ancient sedimentary DNA reveals long-term impact of climate change on northern flora. Full text in Research Archive
• Rijal, Dilli Prasad; Heintzman, Peter D.; Lammers, Youri; Bråthen, Kari Anne; Yoccoz, Nigel & Brown, Antony [Show all 12 contributors for this article] (2020). Temporal pattern of terrestrial plant diversity in northern Fennoscandia. Full text in Research Archive
• Alsos, Inger Greve; Bjune, Anne Elisabeth; Bråthen, Kari Anne; Clarke, Charlotte; Edwards, Mary E. & Ehrich, Dorothee [Show all 26 contributors for this article] (2020). The use of ancient DNA in palaeoecological studies. Full text in Research Archive
• Alsos, Inger Greve; Bjune, Anne Elisabeth; Bråthen, Kari Anne; Charlotte, Clark; Edwards, Mary E. & Ehrich, Dorothee [Show all 26 contributors for this article] (2020). Using ancient and modern DNA to understand effect of climate change on vascular plants. Full text in Research Archive
• Alsos, Inger Greve; Heintzman, Peter D.; Brown, Antony; Rijal, Dilli Prasad; Lorberau, Kelsey & Lammers, Youri [Show all 15 contributors for this article] (2020). Using ancient sedimentary DNA to explore long-term effect of climate change on vegetation. Full text in Research Archive
• Lorberau, Kelsey & Bråthen, Kari Anne (2019). An analysis of what ecological shortfalls paleoecological data is most suited to address: the case of ancient DNA of plants. Full text in Research Archive
• Rijal, Dilli Prasad; Lorberau, Kelsey; Kapfer, Jutta; Støvern, Leif-Einar; Alsos, Inger Greve & Bråthen, Kari Anne (2019). Tracking the past using the present: does sedimentary DNA capture the dominant vegetation growing around a lake? Full text in Research Archive
• Alsos, Inger Greve; Heintzman, Peter D.; Brown, Antony; Rijal, Dilli Prasad; Lorberau, Kelsey & Lammers, Youri [Show all 14 contributors for this article] (2019). How ancient sediment DNA can improve our understanding of past vegetation and the impact of climate change. Full text in Research Archive
• Rijal, Dilli Prasad; Lorberau, Kelsey; Heintzman, Peter D.; Lammers, Youri; Kapfer, Jutta & Støvern, Einar [Show all 11 contributors for this article] (2019). Comparing sedimentary environmental DNA-based vegetation to current vegetation composition around lakes. Full text in Research Archive
• Rijal, Dilli Prasad; Heintzman, Peter D.; Lammers, Youri; Blankholm, Hans Peter; Brown, Antony & Bråthen, Kari Anne [Show all 7 contributors for this article] (2019). Impact of climate and anthropogenic factors on vegetation history: an ancient DNA based vegetation reconstruction from Varanger, northern Norway. Full text in Research Archive
• Heintzman, Peter D.; Rijal, Dilli Prasad; Pastor, Sandra Garces; Lorberau, Kelsey; Lammers, Youri & Clarke, Charlotte L. [Show all 10 contributors for this article] (2019). ECOGEN: a project to examine ecosystem changes and species persistence over time using lake sediment DNA. Full text in Research Archive Show summary

  We can predict potential future ecosystem impacts by examining the effects of analogous past changes. Within the past 12,000 years, there have been periods of both dramatic and relatively minor climate changes that are comparable to the range of predicted future scenarios. Additionally, human land-use impacts have been varied and widespread across Europe during this interval. Palaeoecological records, such as lake sediments, can inform how these drivers of change impacted past ecosystems. Traditionally, pollen has been used to infer ecological changes in sediment records, but its low taxonomic resolution precludes a detailed understanding of turnover and succession events. In contrast, ancient DNA recovered directly from lake sediments (sedaDNA) often yields species-specific information thereby mitigating this issue. The ECOGEN project is using lake sedaDNA to examine the principle drivers of past ecosystem changes (climate and human land-use impacts), principally targeting vascular plants and key herbivores. The project focuses on two major regions: Northern Norway and the European Alps. Both regions have been affected by climatic changes, but the former is far less impacted by past human land-use changes than the latter. The large scale of the project (two regions and up to 40 lake sediment records) also allows for extensive testing of wet-lab and bioinformatic methodologies related to sedaDNA analysis. In this talk, we will outline our major project findings so far, including full vascular plant records from many of our analysed sediment records from Northern Norway. These show distinct regional signals of succession and turnover. Ecological succession in the earliest Holocene tends to be rapid, with diverse plant communities appearing very soon after the Pleistocene-Holocene transition, which indicates swift responses to this short period of severe climatic change. Several records located near archaeological sites also show evidence of human land-use changes, as demonstrated by the appearance of disturbance indicators. These initial findings demonstrate the efficacy of our approach, and they lay the foundation for large-scale regional comparisons to disentangle past drivers of ecosystem change that would improve our predictions of the near future.

• Rijal, Dilli Prasad; Heintzman, Peter D.; Lammers, Youri; Blankholm, Hans Peter; Brown, Antony & Murguzur, Francisco Javier Ancin [Show all 10 contributors for this article] (2019). Ancient sedimentary DNA reveals both climatic and human impact on vegetation history in Varanger, northern Norway. Full text in Research Archive
• Rijal, Dilli Prasad; Heintzman, Peter D.; Lammers, Youri; Blankholm, Hans Peter; Brown, Antony & Murguzur, Francisco Javier Ancin [Show all 10 contributors for this article] (2019). Ancient sedimentary DNA reveals both climatic and human impact on vegetation history in Varanger, northern Norway. Full text in Research Archive
• Rijal, Dilli Prasad; Heintzman, Peter D.; Lammers, Youri; Murguzur, Francisco Javier Ancin; Pitelkova, Iva & Blankholm, Hans Peter [Show all 10 contributors for this article] (2018). Ancient DNA reveals vegetation history near the archeological site in Varanger, northern Norway. Full text in Research Archive
• Barrio, Isabel C.; Lindén, Elin; Beest, Mariska te; Olofsson, Johan; Rocha, Adrian & Soininen, Eeva M [Show all 60 contributors for this article] (2018). Publisher Correction to: Background invertebrate herbivory on dwarf birch (Betula glandulosa-nana complex) increases with temperature and precipitation across the tundra biome. Polar Biology. ISSN 0722-4060. doi: 10.1007/s00300-018-2305-6. Full text in Research Archive
• Bon, Matteo Petit; Inga, Katarina Gunnarsdotter; Fagerholm, Freja; Utsi, Tove Aagnes; Jonsdottir, Inga-Svala & Bråthen, Kari Anne (2017). Strong interplay between seasonality and herbivory determines nutrient dynamics in tundra plants. Full text in Research Archive
• Bon, Matteo Petit; Inga, Katarina Gunnarsdotter; Fagerholm, Freja; Utsi, Tove Aagnes; Jónsdóttir, Ingibjörg Svala & Bråthen, Kari Anne (2017). Herbivore assemblages and seasonality determine nitrogen and phosphorous content in tundra plants. Full text in Research Archive
• Charlotte, Clark; Alsos, Inger Greve; Brown, Antony G; Murguzur, Francisco Javier Ancin; Lammers, Youri & Bråthen, Kari Anne (2016). Komagdalen (2016) The first results from the ECOGEN project. Full text in Research Archive
• Toumi, Maria; Murguzur, Francisco J.A.; Hoset, Katrine S.; Soininen, Eeva M; Vesterinen, Eero & Utsi, Tove Aagnes [Show all 7 contributors for this article] (2016). Rodent species and sex determination from single fecal pellets using near-infrared reflectance spectroscopy (NIRS). Full text in Research Archive
• Bråthen, Kari Anne (2014). Med krekling og gress på sommermenyen. Reindriftsnytt : Boazodoallu-Oddasat. ISSN 0333-4031. 2, p. 42–45. Full text in Research Archive
• Bråthen, Kari Anne; Ravolainen, Virve & Soininen, Eeva M (2014). Den grønne tundraen. Ottar. ISSN 0030-6703. p. 45–51. Full text in Research Archive
• Ravolainen, Virve; Johnstone, Jill; Bråthen, Kari Anne; Henry, Greg & Myers-Smith, Isla (2013). The future's results are in today's planning. Monitoring tundra vegetation. Full text in Research Archive
• Stien, Audun; Bråthen, Kari Anne; Cooper, Elisabeth J.; Ehrich, Dorothee; Hausner, Vera Helene & Henden, John-André [Show all 24 contributors for this article] (2013). COAT - Climate- ecological Observatory for Arctic Tundra. Full text in Research Archive
• Breitschopf, Eva & Bråthen, Kari Anne (2025). Advancing the Integration of Ecology in Landscape Architecture: Employing the Concept of Ecological Filtering to Bridge the Functioning and Aesthetics of Biodiversity Insights from Perception to Practice. UiT Norges arktiske universitet. ISSN 9788282662932. Full text in Research Archive Show summary

  The biodiversity crisis highlights the need for landscape architecture to include ecological knowledge—the understanding of how organisms and the environment interact. My thesis addresses two key challenges for this integration: the complexity of ecological knowledge and the assumption that ecology-based designs are less visually appealing. I developed a framework to make ecological concepts easier to use for landscape architects. Using this framework, I found that while ecology is increasingly included in European landscape architecture, important factors for thriving ecosystems are often overlooked. Through surveys on experimental plant communities, I explored how people view plant biodiversity. Contrary to the belief that ecology-based designs look "messy," I found that high biodiversity can make vegetation more attractive. My findings show that integrating ecological knowledge into landscape architecture can support the creation of functional, thriving and beautiful vegetation.

• Pedersen, Åshild Ønvik; Jepsen, Jane Uhd; Paulsen, Ingrid Marie Garfelt; Fuglei, Eva; Mosbacher, Jesper Bruun & Ravolainen, Virve [Show all 22 contributors for this article] (2021). Norwegian Arctic tundra: a panel-based assessment of ecosystem condition. Norsk Polarinstitutt. ISSN 9788276664409. Full text in Research Archive
• Hansen, Inger; Eilertsen, Svein Morten; Sørensen, Ole Jakob; Mørk, Torill; Bråthen, Kari Anne & Johansen, Bernt [Show all 10 contributors for this article] (2019). Tap av tamrein – et kunnskapsgrunnlag. NIBIO. ISSN 9788217024781. Full text in Research Archive Show summary

  Tap av dyr er en utfordring og et sentralt tema i norsk tamreindrift. Dette kunnskapsgrunnlaget beskriver status for hva vi vet om tapsomfang, tapsårsaker og tapsammenhenger innen områdene tap av rein til rovvilt, sykdom, klimarelatert tap, påkjørsler og grunnet kumulative effekter. Videre setter den fokus på forebyggende tiltak og hvilke felt man trenger ytterligere kunnskapsbygging på. Gjennomgående mangler kunnskap om sammenhengene mellom de ulike årsaksfaktorene samt bedre dokumentasjon av det tidlige kalvetapet.

View all works in NVA