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Publications (10 of 61) Show all publications
Maes, S., Dietrich, J., Midolo, G., Schwieger, S., Kummu, M., Vandvik, V., . . . Dorrepaal, E. (2024). Environmental drivers of increased ecosystem respiration in a warming tundra. Nature, 629(8010), 105-113
Open this publication in new window or tab >>Environmental drivers of increased ecosystem respiration in a warming tundra
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2024 (English)In: Nature, ISSN 0028-0836, E-ISSN 1476-4687, Vol. 629, no 8010, p. 105-113Article in journal (Refereed) Published
Abstract [en]

Arctic and alpine tundra ecosystems are large reservoirs of organic carbon1,2. Climate warming may stimulate ecosystem respiration and release carbon into the atmosphere3,4. The magnitude and persistency of this stimulation and the environmental mechanisms that drive its variation remain uncertain5–7. This hampers the accuracy of global land carbon–climate feedback projections7,8. Here we synthesize 136 datasets from 56 open-top chamber in situ warming experiments located at 28 arctic and alpine tundra sites which have been running for less than 1 year up to 25 years. We show that a mean rise of 1.4 °C [confidence interval (CI) 0.9–2.0 °C] in air and 0.4 °C [CI 0.2–0.7 °C] in soil temperature results in an increase in growing season ecosystem respiration by 30% [CI 22–38%] (n = 136). Our findings indicate that the stimulation of ecosystem respiration was due to increases in both plant-related and microbial respiration (n = 9) and continued for at least 25 years (n = 136). The magnitude of the warming effects on respiration was driven by variation in warming-induced changes in local soil conditions, that is, changes in total nitrogen concentration and pH and by context-dependent spatial variation in these conditions, in particular total nitrogen concentration and the carbon:nitrogen ratio. Tundra sites with stronger nitrogen limitations and sites in which warming had stimulated plant and microbial nutrient turnover seemed particularly sensitive in their respiration response to warming. The results highlight the importance of local soil conditions and warming-induced changes therein for future climatic impacts on respiration.

Place, publisher, year, edition, pages
Springer Nature, 2024
National Category
Climate Research
Identifiers
urn:nbn:se:umu:diva-223836 (URN)10.1038/s41586-024-07274-7 (DOI)38632407 (PubMedID)2-s2.0-85190691054 (Scopus ID)
Funder
Swedish Research Council, 2018-04004Knut and Alice Wallenberg Foundation, 2020.0126Swedish Research Council Formas, 2013-655Swedish Research Council Formas, 2021-02449EU, European Research CouncilEU, Horizon 2020Academy of FinlandThe Research Council of Norway
Available from: 2024-04-30 Created: 2024-04-30 Last updated: 2024-06-19Bibliographically approved
van Zuijlen, K., Kassel, M., Dorrepaal, E. & Lett, S. (2024). Frost damage measured by electrolyte leakage in subarctic bryophytes increases with climate warming. Journal of Ecology, 112(2), 220-232
Open this publication in new window or tab >>Frost damage measured by electrolyte leakage in subarctic bryophytes increases with climate warming
2024 (English)In: Journal of Ecology, ISSN 0022-0477, E-ISSN 1365-2745, Vol. 112, no 2, p. 220-232Article in journal (Refereed) Published
Abstract [en]

Observed climate change in northern high latitudes is strongest in winter, but still relatively little is known about the effects of winter climate change on tundra ecosystems. Ongoing changes in winter climate and snow cover will change the intensity, duration and frequency of frost events. Bryophytes form a major component of northern ecosystems but their responses to winter climate changes are largely unknown.

Here, we studied how changes in overall winter climate and snow regime affect frost damage in three common bryophyte taxa that differ in desiccation tolerance in a subarctic tundra ecosystem. We used a snow manipulation experiment where bryophyte cores were transplanted from just above the tree line to similar elevation (i.e. current cold climate) and lower elevation (i.e. near-future warmer climate scenario) in Abisko, Sweden. Here, we measured frost damage in shoots of Ptilidium ciliare, Hylocomium splendens and Sphagnum fuscum with the relative electrolyte leakage (REL) method, during late winter and spring in two consecutive years. We hypothesized that frost damage would be lower in a milder climate (low site) and higher under reduced snow cover and that taxa from moister habitats with assumed low desiccation tolerance would be more sensitive to lower temperature and thinner snow cover than those from drier and more exposed habitats.

Contrary to our expectations, frost damage was highest at low elevation, while the effect of snow treatment differed across sites and taxa. At the high site, frost damage was reduced under snow addition in the taxon with the assumed lowest desiccation tolerance, S. fuscum. Surprisingly, frost damage increased with mean temperature in the bryophyte core of the preceding 14 days leading up to REL measurements and decreased with higher frost degree sums, that is, was highest in the milder climate at the low site.

Synthesis Our results imply that climate warming in late winter and spring increases frost damage in bryophytes. Given the high abundance of bryophytes in tundra ecosystems, higher frost damage could alter the appearance and functioning of the tundra landscape, although the short and long-term effects on bryophyte fitness remain to be studied.

Place, publisher, year, edition, pages
John Wiley & Sons, 2024
Keywords
desiccation tolerance, frost sensitivity, mosses, relative electrolyte leakage (REL), snow manipulation experiment, tundra, winter ecology
National Category
Ecology
Identifiers
urn:nbn:se:umu:diva-218137 (URN)10.1111/1365-2745.14236 (DOI)001113739200001 ()2-s2.0-85178954236 (Scopus ID)
Funder
The Kempe Foundations, JCK-1112Swedish Research Council
Available from: 2023-12-18 Created: 2023-12-18 Last updated: 2024-04-30Bibliographically approved
Lett, S., Christiansen, C. T., Dorrepaal, E. & Michelsen, A. (2024). Moss species and precipitation mediate experimental warming stimulation of growing season N2 fixation in subarctic tundra. Global Change Biology, 30(7), Article ID e17401.
Open this publication in new window or tab >>Moss species and precipitation mediate experimental warming stimulation of growing season N2 fixation in subarctic tundra
2024 (English)In: Global Change Biology, ISSN 1354-1013, E-ISSN 1365-2486, Vol. 30, no 7, article id e17401Article in journal (Refereed) Published
Abstract [en]

Climate change in high latitude regions leads to both higher temperatures and more precipitation but their combined effects on terrestrial ecosystem processes are poorly understood. In nitrogen (N) limited and often moss-dominated tundra and boreal ecosystems, moss-associated N2 fixation is an important process that provides new N. We tested whether high mean annual precipitation enhanced experimental warming effects on growing season N2 fixation in three common arctic-boreal moss species adapted to different moisture conditions and evaluated their N contribution to the landscape level. We measured in situ N2 fixation rates in Hylocomium splendens, Pleurozium schreberi and Sphagnum spp. from June to September in subarctic tundra in Sweden. We exposed mosses occurring along a natural precipitation gradient (mean annual precipitation: 571–1155 mm) to 8 years of experimental summer warming using open-top chambers before our measurements. We modelled species-specific seasonal N input to the ecosystem at the colony and landscape level. Higher mean annual precipitation clearly increased N2 fixation, especially during peak growing season and in feather mosses. For Sphagnum-associated N2 fixation, high mean annual precipitation reversed a small negative warming response. By contrast, in the dry-adapted feather moss species higher mean annual precipitation led to negative warming effects. Modelled total growing season N inputs for Sphagnum spp. colonies were two to three times that of feather mosses at an area basis. However, at the landscape level where feather mosses were more abundant, they contributed 50% more N than Sphagnum. The discrepancy between modelled estimates of species-specific N input via N2 fixation at the moss core versus ecosystem scale, exemplify how moss cover is essential for evaluating impact of altered N2 fixation. Importantly, combined effects of warming and higher mean annual precipitation may not lead to similar responses across moss species, which could affect moss fitness and their abilities to buffer environmental changes.

Place, publisher, year, edition, pages
John Wiley & Sons, 2024
Keywords
alpine ecosystem, arctic-boreal bryophytes, Hylocomium splendens, landscape scale, moisture, Pleurozium schreberi, Sphagnum, temperature
National Category
Ecology
Identifiers
urn:nbn:se:umu:diva-228072 (URN)10.1111/gcb.17401 (DOI)2-s2.0-85199152634 (Scopus ID)
Funder
The Kempe Foundations, JKC-1112Knut and Alice Wallenberg Foundation, 2017.0298Independent Research Fund Denmark, 0135-00140BEU, Horizon 2020, 797446Danish National Research Foundation, CENPERM DNRF100
Available from: 2024-07-31 Created: 2024-07-31 Last updated: 2024-07-31Bibliographically approved
Hollister, R. D., Elphinstone, C., Henry, G. H. R., Bjorkman, A. D., Klanderud, K., Björk, R. G., . . . Wookey, P. A. (2023). A review of open top chamber (OTC) performance across the ITEX Network. Arctic Science, 9(2), 331-344
Open this publication in new window or tab >>A review of open top chamber (OTC) performance across the ITEX Network
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2023 (English)In: Arctic Science, E-ISSN 2368-7460, Vol. 9, no 2, p. 331-344Article, review/survey (Refereed) Published
Abstract [en]

Open top chambers (OTCs) were adopted as the recommended warmingmechanism by the International Tundra Experiment network in the early 1990s. Since then, OTCs have been deployed across the globe. Hundreds of papers have reported the impacts of OTCs on the abiotic environment and the biota. Here, we review the impacts of the OTC on the physical environment, with comments on the appropriateness of using OTCs to characterize the response of biota to warming. The purpose of this review is to guide readers to previously published work and to provide recommendations for continued use of OTCs to understand the implications of warming on low stature ecosystems. In short, the OTC is a useful tool to experimentally manipulate temperature; however, the characteristics and magnitude of warming varies greatly in different environments; therefore, it is important to document chamber performance to maximize the interpretation of biotic response.When coupled with long-term monitoring, warming experiments are a valuable means to understand the impacts of climate change on natural ecosystems.

Place, publisher, year, edition, pages
Canadian Science Publishing, 2023
Keywords
Alpine, Arctic, Large-scale coordinated experiment, Tundra, Warming experiment
National Category
Climate Research Ecology
Identifiers
urn:nbn:se:umu:diva-212056 (URN)10.1139/as-2022-0030 (DOI)000929508500001 ()2-s2.0-85140018617 (Scopus ID)
Available from: 2023-07-18 Created: 2023-07-18 Last updated: 2023-07-18Bibliographically approved
Blume-Werry, G., Dorrepaal, E., Keuper, F., Kummu, M., Wild, B. & Weedon, J. T. (2023). Arctic rooting depth distribution influences modelled carbon emissions but cannot be inferred from aboveground vegetation type. New Phytologist, 240(2), 502-514
Open this publication in new window or tab >>Arctic rooting depth distribution influences modelled carbon emissions but cannot be inferred from aboveground vegetation type
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2023 (English)In: New Phytologist, ISSN 0028-646X, E-ISSN 1469-8137, Vol. 240, no 2, p. 502-514Article in journal (Refereed) Published
Abstract [en]

The distribution of roots throughout the soil drives depth-dependent plant–soil interactions and ecosystem processes, particularly in arctic tundra where plant biomass, is predominantly belowground. Vegetation is usually classified from aboveground, but it is unclear whether such classifications are suitable to estimate belowground attributes and their consequences, such as rooting depth distribution and its influence on carbon cycling. We performed a meta-analysis of 55 published arctic rooting depth profiles, testing for differences both between distributions based on aboveground vegetation types (Graminoid, Wetland, Erect-shrub, and Prostrate-shrub tundra) and between ‘Root Profile Types’ for which we defined three representative and contrasting clusters. We further analyzed potential impacts of these different rooting depth distributions on rhizosphere priming-induced carbon losses from tundra soils. Rooting depth distribution hardly differed between aboveground vegetation types but varied between Root Profile Types. Accordingly, modelled priming-induced carbon emissions were similar between aboveground vegetation types when they were applied to the entire tundra, but ranged from 7.2 to 17.6 Pg C cumulative emissions until 2100 between individual Root Profile Types. Variations in rooting depth distribution are important for the circumpolar tundra carbon-climate feedback but can currently not be inferred adequately from aboveground vegetation type classifications.

Place, publisher, year, edition, pages
John Wiley & Sons, 2023
Keywords
arctic tundra, permafrost, plant–soil interactions, rhizosphere priming effect, root biomass, root vertical distribution strategies, rooting depth
National Category
Ecology
Identifiers
urn:nbn:se:umu:diva-209191 (URN)10.1111/nph.18998 (DOI)000994763700001 ()37227127 (PubMedID)2-s2.0-85160080474 (Scopus ID)
Funder
EU, European Research Council, 101039588EU, Horizon 2020, 819202
Available from: 2023-06-12 Created: 2023-06-12 Last updated: 2023-12-19Bibliographically approved
Sytiuk, A., Hamard, S., Céréghino, R., Dorrepaal, E., Geissel, H., Küttim, M., . . . Jassey, V. E. J. (2023). Linkages between Sphagnum metabolites and peatland CO2 uptake are sensitive to seasonality in warming trends. New Phytologist, 237(4), 1164-1178
Open this publication in new window or tab >>Linkages between Sphagnum metabolites and peatland CO2 uptake are sensitive to seasonality in warming trends
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2023 (English)In: New Phytologist, ISSN 0028-646X, E-ISSN 1469-8137, Vol. 237, no 4, p. 1164-1178Article in journal (Refereed) Published
Abstract [en]

Plants produce a wide diversity of metabolites. Yet, our understanding of how shifts in plant metabolites as a response to climate change feedback on ecosystem processes remains scarce. Here, we test to what extent climate warming shifts the seasonality of metabolites produced by Sphagnum mosses, and what are the consequences of these shifts for peatland C uptake.

We used a reciprocal transplant experiment along a climate gradient in Europe to simulate climate change. We evaluated the responses of primary and secondary metabolites in five Sphagnum species and related their responses to gross ecosystem productivity (GEP).

When transplanted to a warmer climate, Sphagnum species showed consistent responses to warming, with an upregulation of either their primary or secondary metabolite according to seasons. Moreover, these shifts were correlated to changes in GEP, especially in spring and autumn.

Our results indicate that the Sphagnum metabolome is very plastic and sensitive to warming. We also show that warming-induced changes in the seasonality of Sphagnum metabolites have consequences on peatland GEP. Our findings demonstrate the capacity for plant metabolic plasticity to impact ecosystem C processes and reveal a further mechanism through which Sphagnum could shape peatland responses to climate change.

Place, publisher, year, edition, pages
John Wiley & Sons, 2023
Keywords
carbon cycle, climate change, climate feedback, intraspecific variability, phenotypic plasticity, plant metabolism, seasonality, Sphagnum
National Category
Climate Research
Identifiers
urn:nbn:se:umu:diva-201955 (URN)10.1111/nph.18601 (DOI)000894101600001 ()36336780 (PubMedID)2-s2.0-85143969438 (Scopus ID)
Available from: 2022-12-28 Created: 2022-12-28 Last updated: 2023-07-13Bibliographically approved
Väisänen, M., Klaminder, J., Ylänne, H., Teuber, L., Dorrepaal, E. & Krab, E. J. (2023). Tundra cryogenic land surface processes and CO2–C balance in sub-Arctic alpine environment withstand winter and spring warming. Environmental Research: Climate, 2(2), Article ID 021001.
Open this publication in new window or tab >>Tundra cryogenic land surface processes and CO2–C balance in sub-Arctic alpine environment withstand winter and spring warming
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2023 (English)In: Environmental Research: Climate, E-ISSN 2752-5295, Vol. 2, no 2, article id 021001Article in journal (Refereed) Published
Abstract [en]

Cryogenic land surface processes (CLSPs), such as cryoturbation, are currently active in landscapes covering 25% of our planet where they dictate key functions, such as carbon (C) cycling, and maintain patterned landscape features. While CLSPs are expected to diminish in the near future due to milder winters especially in the southern parts of the Arctic, the shifts in C cycling in these landscapes may be more complex, since climate change can affect C cycling directly but also indirectly via CLSPs. Here, we study the effects of changing winter and spring climate on CLSPs and C cycling in non-sorted circles consisting of barren frost boils and their vegetated rims. We do this by measuring cryoturbation and ecosystem CO2 fluxes repeatedly in alpine subarctic tundra where temperatures during naturally snow covered period have been experimentally increased with snow-trapping fences and temperatures during winter and spring period after snowmelt have been increased with insulating fleeces. Opposite to our hypothesis, warming treatments did not decrease cryoturbation. However, winter warming via deeper snow increased ecosystem C sink during summer by decreasing ecosystem CO2 release in the frost boils and by counterbalancing the negative effects of cryoturbation on plant CO2 uptake in the vegetated rims. Our results suggest that short-term changes in winter and spring climate may not alter cryoturbation and jeopardize the tundra C sink.

Place, publisher, year, edition, pages
Institute of Physics Publishing (IOPP), 2023
Keywords
non-sorted circle, differential heave, greenhouse gas, snow fence, greenness, light-response, modeling
National Category
Climate Research Physical Geography
Identifiers
urn:nbn:se:umu:diva-220232 (URN)10.1088/2752-5295/acc08b (DOI)
Funder
Swedish Research Council Formas, 2017-01182Knut and Alice Wallenberg Foundation, KAW 2012.0152Swedish Research Council, 621-2011-5444
Available from: 2024-01-30 Created: 2024-01-30 Last updated: 2024-01-31Bibliographically approved
Jessen, M.-T., Krab, E. J., Lett, S., Nilsson, M.-C., Teuber, L., Wardle, D. A. & Dorrepaal, E. (2023). Understory functional groups and fire history but not experimental warming drive tree seedling performance in unmanaged boreal forests. Frontiers in Forests and Global Change, 6, Article ID 1130532.
Open this publication in new window or tab >>Understory functional groups and fire history but not experimental warming drive tree seedling performance in unmanaged boreal forests
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2023 (English)In: Frontiers in Forests and Global Change, E-ISSN 2624-893X, Vol. 6, article id 1130532Article in journal (Refereed) Published
Abstract [en]

Introduction: Survival and growth of tree seedlings are key processes of regeneration in forest ecosystems. However, little is known about how climate warming modulates seedling performance either directly or in interaction with understory vegetation and post-fire successional stages.

Methods: We measured survival (over 3 years) and growth of seedlings of three tree species (Betula pubescens, Pinus sylvestris, and Picea abies) in a full-factorial field experiment with passive warming and removal of two plant functional groups (feather moss and/or ericaceous shrubs) along a post-fire chronosequence in an unmanaged boreal forest.

Results: Warming had no effect on seedling survival over time or on relative biomass growth. Meanwhile, moss removal greatly increased seedling survival overall, while shrub removal canceled this effect for B. pubescens seedlings. In addition, B. pubescens and P. sylvestris survival benefitted most from moss removal in old forests (>260 years since last fire disturbance). In contrast to survival, seedling growth was promoted by shrub removal for two out of three species, i.e., P. sylvestris and P. abies, meaning that seedling survival and growth are governed by different understory functional groups affecting seedling performance through different mechanism and modes of action.

Discussion: Our findings highlight that understory vegetation and to a lesser extent post-fire successional stage are important drivers of seedling performance while the direct effect of climate warming is not. This suggests that tree regeneration in future forests may be more responsive to changes in understory vegetation or fire regime, e.g., indirectly caused by warming, than to direct or interactive effects of rising temperatures.

Place, publisher, year, edition, pages
Frontiers Media S.A., 2023
Keywords
climate change, forest fire, forest regeneration, moss, plant functional group removal, shrubs, survival
National Category
Forest Science Ecology
Identifiers
urn:nbn:se:umu:diva-209166 (URN)10.3389/ffgc.2023.1130532 (DOI)000994826400001 ()2-s2.0-85160109116 (Scopus ID)
Funder
The Kempe Foundations, JCK-1112Swedish Research Council, 621-2011-5444Knut and Alice Wallenberg Foundation, 2012.0152
Available from: 2023-06-26 Created: 2023-06-26 Last updated: 2024-06-11Bibliographically approved
Sytiuk, A., Céréghino, R., Hamard, S., Delarue, F., Dorrepaal, E., Küttim, M., . . . Jassey, V. E. J. (2022). Biochemical traits enhance the trait concept in Sphagnum ecology. Oikos (4), Article ID e09119.
Open this publication in new window or tab >>Biochemical traits enhance the trait concept in Sphagnum ecology
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2022 (English)In: Oikos, ISSN 0030-1299, E-ISSN 1600-0706, no 4, article id e09119Article in journal (Refereed) Published
Abstract [en]

Sphagnum mosses are key to northern peatland carbon sequestration. They have a range of morphological and anatomical characteristics that allow them to cope with environmental stress. Sphagnum also produces a plethora of biochemicals that may prevent stress-induced cell-damage. However, the linkages between Sphagnum anatomical, morphological and biochemical traits (i.e. metabolites, pigments and antioxidant enzyme activities) are poorly known, neither are their joint responses to environmental change. Here, we quantify and link an array of Sphagnum anatomical, morphological and biochemical traits in five Sphagnum-dominated peatlands distributed along a latitudinal gradient in Europe, covering a range of regional and local environmental conditions. Sphagnum morphological and anatomical traits were intrinsically linked to Sphagnum metabolites and enzyme activities, and these relationships were driven by shared responses to local and regional environmental factors. More particularly, we found that Sphagnum traits can be grouped into four clusters related to growth, biomass, defense and water stress tolerance. We used regional and local environmental conditions data to further show that biochemicals and their specific linkages with some morphological traits describe dimensions of physiology not captured by anatomical and morphological traits alone. These results suggest that Sphagnum morphology and function is rooted in the metabolome, and that incorporating biochemicals into the functional trait space concept can enhance our mechanistic understanding and predictive power in Sphagnum ecology.

Place, publisher, year, edition, pages
John Wiley & Sons, 2022
Keywords
antioxidant enzyme activities, bryophytes, climate change, metabolites, peatlands, Sphagnum
National Category
Ecology
Identifiers
urn:nbn:se:umu:diva-192666 (URN)10.1111/oik.09119 (DOI)000754561200001 ()2-s2.0-85124505374 (Scopus ID)
Funder
Swedish National Space Board, 179/18Swedish National Space Board, 189/16
Available from: 2022-02-21 Created: 2022-02-21 Last updated: 2023-03-24Bibliographically approved
Lett, S., Jónsdóttir, I. S., Becker-Scarpitta, A., Christiansen, C. T., During, H., Ekelund, F., . . . van Zuijlen, K. (2022). Can bryophyte groups increase functional resolution in tundra ecosystems?. Arctic Science, 8(3), 609-637
Open this publication in new window or tab >>Can bryophyte groups increase functional resolution in tundra ecosystems?
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2022 (English)In: Arctic Science, E-ISSN 2368-7460, Vol. 8, no 3, p. 609-637Article in journal (Refereed) Published
Abstract [en]

The relative contribution of bryophytes to plant diversity, primary productivity, and ecosystem functioning increases towards colder climates. Bryophytes respond to environmental changes at the species level, but because bryophyte species are relatively difficult to identify, they are often lumped into one functional group. Consequently, bryophyte function remains poorly resolved. Here, we explore how higher resolution of bryophyte functional diversity can be encouraged and implemented in tundra ecological studies. We briefly review previous bryophyte functional classifications and the roles of bryophytes in tundra ecosystems and their susceptibility to environmental change. Based on shoot morphology and colony organization, we then propose twelve easily distinguishable bryophyte functional groups. To illustrate how bryophyte functional groups can help elucidate variation in bryophyte effects and responses, we compiled existing data on water holding capacity, a key bryophyte trait. Although plant functional groups can mask potentially high interspecific and intraspecific variability, we found better separation of bryophyte functional group means compared with previous grouping systems regarding water holding capacity. This suggests that our bryophyte functional groups truly represent variation in the functional roles of bryophytes in tundra ecosystems. Lastly, we provide recommendations to improve the monitoring of bryophyte community changes in tundra study sites.

Place, publisher, year, edition, pages
Canadian Science Publishing, 2022
Keywords
Arctic–Alpine, environmental change, functional traits, mosses, water holding capacity
National Category
Ecology
Identifiers
urn:nbn:se:umu:diva-203240 (URN)10.1139/as-2020-0057 (DOI)000928440900004 ()2-s2.0-85140017986 (Scopus ID)
Funder
EU, Horizon 2020, 797446
Available from: 2023-01-17 Created: 2023-01-17 Last updated: 2023-09-05Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0002-0523-2471

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