| 1. |
- Sarneel, Judith M., et al.
(författare)
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Reading tea leaves worldwide : decoupled drivers of initial litter decomposition mass-loss rate and stabilization
- 2024
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Ingår i: Ecology Letters. - : John Wiley & Sons. - 1461-023X .- 1461-0248. ; 27:5
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Tidskriftsartikel (refereegranskat)abstract
- The breakdown of plant material fuels soil functioning and biodiversity. Currently, process understanding of global decomposition patterns and the drivers of such patterns are hampered by the lack of coherent large-scale datasets. We buried 36,000 individual litterbags (tea bags) worldwide and found an overall negative correlation between initial mass-loss rates and stabilization factors of plant-derived carbon, using the Tea Bag Index (TBI). The stabilization factor quantifies the degree to which easy-to-degrade components accumulate during early-stage decomposition (e.g. by environmental limitations). However, agriculture and an interaction between moisture and temperature led to a decoupling between initial mass-loss rates and stabilization, notably in colder locations. Using TBI improved mass-loss estimates of natural litter compared to models that ignored stabilization. Ignoring the transformation of dead plant material to more recalcitrant substances during early-stage decomposition, and the environmental control of this transformation, could overestimate carbon losses during early decomposition in carbon cycle models.
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| 2. |
- Ely, K. S., et al.
(författare)
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A reporting format for leaf-level gas exchange data and metadata
- 2021
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Ingår i: Ecological Informatics. - : Elsevier BV. - 1574-9541. ; 61
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Tidskriftsartikel (refereegranskat)abstract
- Leaf-level gas exchange data support the mechanistic understanding of plant fluxes of carbon and water. These fluxes inform our understanding of ecosystem function, are an important constraint on parameterization of terrestrial biosphere models, are necessary to understand the response of plants to global environmental change, and are integral to efforts to improve crop production. Collection of these data using gas analyzers can be both technically challenging and time consuming, and individual studies generally focus on a small range of species, restricted time periods, or limited geographic regions. The high value of these data is exemplified by the many publications that reuse and synthesize gas exchange data, however the lack of metadata and data reporting conventions make full and efficient use of these data difficult. Here we propose a reporting format for leaf-level gas exchange data and metadata to provide guidance to data contributors on how to store data in repositories to maximize their discoverability, facilitate their efficient reuse, and add value to individual datasets. For data users, the reporting format will better allow data repositories to optimize data search and extraction, and more readily integrate similar data into harmonized synthesis products. The reporting format specifies data table variable naming and unit conventions, as well as metadata characterizing experimental conditions and protocols. For common data types that were the focus of this initial version of the reporting format, i.e., survey measurements, dark respiration, carbon dioxide and light response curves, and parameters derived from those measurements, we took a further step of defining required additional data and metadata that would maximize the potential reuse of those data types. To aid data contributors and the development of data ingest tools by data repositories we provided a translation table comparing the outputs of common gas exchange instruments. Extensive consultation with data collectors, data users, instrument manufacturers, and data scientists was undertaken in order to ensure that the reporting format met community needs. The reporting format presented here is intended to form a foundation for future development that will incorporate additional data types and variables as gas exchange systems and measurement approaches advance in the future. The reporting format is published in the U.S. Department of Energy?s ESS-DIVE data repository, with documentation and future development efforts being maintained in a version control system.
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| 3. |
- Jónsdóttir, I. S., et al.
(författare)
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Intraspecific trait variability is a key feature underlying high Arctic plant community resistance to climate warming
- 2022
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Ingår i: Ecological Monographs. - : Wiley. - 0012-9615 .- 1557-7015.
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Tidskriftsartikel (refereegranskat)abstract
- In the high Arctic, plant community species composition generally responds slowly to climate warming, whereas less is known about the community functional trait responses and consequences for ecosystem functioning. Slow species turnover and large distribution ranges of many Arctic plant species suggest a significant role of intraspecific trait variability in functional responses to climate change. Here, we compare taxonomic and functional community compositional responses to a long-term (17years) warming experiment in Svalbard, replicated across three major high Arctic habitats shaped by topography and contrasting snow regimes. We observed taxonomic compositional changes in all plant communities over time. Still, responses to experimental warming were minor and most pronounced in the drier habitats with relatively early snowmelt timing and long growing seasons (Cassiope and Dryas heaths). The habitats were clearly separated in functional trait space, defined by twelve size- and leaf economics-related traits, primarily due to interspecific trait variation. Functional traits also responded to experimental warming, most prominently in the Dryas heath and mostly due to intraspecific trait variation. Leaf area and leaf mass increased, and leaf δ15N decreased in response to the warming treatment. Intraspecific trait variability ranged between 30% and 71% of the total trait variation, reflecting functional resilience of those communities, dominated by long-lived plants, due to either phenotypic plasticity or genotypic variation that most likely underlies the observed resistance of high Arctic vegetation to climate warming. We further explored the consequences of trait variability for ecosystem functioning by measuring peak season CO2 fluxes. Together, environmental, taxonomic, and functional trait variables explained a large proportion of the variation in net ecosystem exchange (NEE), which increased when intraspecific trait variation was accounted for. In contrast, even though ecosystem respiration and gross ecosystem production both increased in response to warming across habitats, they were mainly driven by the direct kinetic impacts of temperature on plant physiology and biochemical processes. Our study shows that long-term experimental warming has a modest but significant effect on plant community functional trait composition and suggests that intraspecific trait variability is a key feature underlying high Arctic ecosystem resistance to climate warming.
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| 4. |
- Karjalainen, Teemu V., et al.
(författare)
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Subacromial decompression surgery for rotator cuff disease
- 2019
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Ingår i: Cochrane Database of Systematic Reviews. - : WILEY. - 1469-493X. ; :1
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Forskningsöversikt (refereegranskat)abstract
- Background Surgery for rotator cuff disease is usually used after non-operative interventions have failed, although our Cochrane Review, first published in 2007, found that there was uncertain clinical benefit following subacromial decompression surgery. Objectives To synthesise the available evidence of the benefits and harms of subacromial decompression surgery compared with placebo, no intervention or non-surgical interventions in people with rotator cuff disease (excluding full thickness rotator cuff tears). Search methods We searched CENTRAL, MEDLINE, Embase, Clinicaltrials. gov and WHO ICRTP registry from 2006 until 22 October 2018, unrestricted by language. Selection criteria We included randomised and quasi-randomised controlled trials (RCTs) of adults with rotator cuff disease (excluding full-thickness tears), that compared subacromial decompression surgery with placebo, no treatment, or any other non-surgical interventions. As it is least prone to bias, subacromial decompression compared with placebo was the primary comparison. Other comparisons were subacromial decompression versus exercises or non-operative treatment. Major outcomes were mean pain scores, shoulder function, quality of life, participant global assessment of success, adverse events and serious adverse events. The primary endpoint for this review was one year. For serious adverse events, we also included data from prospective cohort studies designed to record harms that evaluated subacromial decompression surgery or shoulder arthroscopy. Data collection and analysis We used standard methodologic procedures expected by Cochrane. Main results We included eight trials, with a total of 1062 randomised participants with rotator cuff disease, all with subacromial impingement. Two trials (506 participants) compared arthroscopic subacromial decompression with arthroscopy only (placebo surgery), with all groups receiving postoperative exercises. These trials included a third treatment group: no treatment (active monitoring) in one and exercises in the other. Six trials (556 participants) compared arthroscopic subacromial decompression followed by exercises with exercises alone. Two of these trials included a third arm: sham laser in one and open subacromial decompression in the other. Trial size varied from 42 to 313 participants. Participant mean age ranged between 42 and 65 years. Only two trials reported mean symptom duration (18 to 22 months in one trial and 30 to 31 months in the other), two did not report duration and four reported it categorically. Both placebo-controlled trials were at low risk of bias for the comparison of surgery versus placebo surgery. The other trials were at high risk of bias for several criteria, most notably at risk of performance or detection bias due to lack of participant and personnel blinding. We have restricted the reporting of results of benefits in the Abstract to the placebo-controlled trials. Compared with placebo, high-certainty evidence indicates that subacromial decompression provides no improvement in pain, shoulder function, or health-related quality of life up to one year, and probably no improvement in global success (moderate-certainty evidence, downgraded due to imprecision). At one year, mean pain (on a scale zero to 10, higher scores indicate more pain), was 2.9 points after placebo surgery and 0.26 better (0.84 better to 0.33 worse), after subacromial decompression (284 participants), an absolute difference of 3%(8% better to 3% worse), and relative difference of 4% (12% better to 5% worse). At one year, mean function (on a scale 0 to 100, higher score indicating better outcome), was 69 points after placebo surgery and 2.8 better (1.4 worse to 6.9 better), after surgery (274 participants), an absolute difference of 3% (7% better to 1% worse), and relative difference of 9% (22% better to 4% worse). Global success rate was 97/148 (or 655 per 1000), after placebo and 101/142 (or 708 per 1000) after surgery corresponding to RR 1.08 (95% CI 0.93 to 1.27). Healthrelated quality of life was 0.73 units (European Quality of Life EQ-5D, -0.59 to 1, higher score indicating better quality of life), after placebo and 0.03 units worse (0.011 units worse to 0.06 units better), after subacromial decompression (285 participants), an absolute difference of 1.3% (5% worse to 2.5% better), and relative difference of 4% (15% worse to 7% better). Adverse events including frozen shoulder or transientminor complications of surgery were reported in approximately 3% of participants across treatment groups in two randomised controlled trials, but due to low event rates we are uncertain if the risks differ between groups: 5/165 (37 per 1000) reported adverse events with subacromial decompression and 9/241 (34 per 1000) with placebo or nonoperative treatment, RR 0.91 (95% CI 0.31 to 2.65) (moderate-certainty evidence, downgraded due to imprecision). The trials did not report serious adverse events. Based upon moderate-certainty evidence from two observational trials from the same prospective surgery registry, which also included other shoulder arthroscopic procedures (downgraded for indirectness), the incidence proportion of serious adverse events within 30 days following surgery was 0.5% (0.4% to 0.7%; data collected 2006 to 2011), or 0.6% (0.5 % to 0.7%; data collected 2011 to 2013). Serious adverse events such as deep infection, pulmonary embolism, nerve injury, and death have been observed in participants following shoulder surgery. Authors conclusions The data in this review do not support the use of subacromial decompression in the treatment of rotator cuff disease manifest as painful shoulder impingement. High-certainty evidence shows that subacromial decompression does not provide clinically important benefits over placebo in pain, function or health-related quality of life. Including results from open-label trials (with high risk of bias) did not change the estimates considerably. Due to imprecision, we downgraded the certainty of the evidence to moderate for global assessment of treatment success; there was probably no clinically important benefit in this outcome either compared with placebo, exercises or non-operative treatment. Adverse event rates were low, 3% or less across treatment groups in the trials, which is consistent with adverse event rates reported in the two observational studies. Although precise estimates are unknown, the risk of serious adverse events is likely less than 1%.
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| 5. |
- Maes, S.L., et al.
(författare)
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Environmental drivers of increased ecosystem respiration in a warming tundra
- 2024
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Ingår i: Nature. - : Springer Nature. - 0028-0836 .- 1476-4687. ; 629:8010, s. 105-113
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Tidskriftsartikel (refereegranskat)abstract
- Arctic and alpine tundra ecosystems are large reservoirs of organic carbon. Climate warming may stimulate ecosystem respiration and release carbon into the atmosphere. The magnitude and persistency of this stimulation and the environmental mechanisms that drive its variation remain uncertain. This hampers the accuracy of global land carbon–climate feedback projections. 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.
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| 6. |
- Keetz, Lasse T., et al.
(författare)
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Climate–ecosystem modelling made easy : The Land Sites Platform
- 2023
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Ingår i: Global Change Biology. - 1354-1013. ; 29:15, s. 4440-4452
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Tidskriftsartikel (refereegranskat)abstract
- Dynamic Global Vegetation Models (DGVMs) provide a state-of-the-art process-based approach to study the complex interplay between vegetation and its physical environment. For example, they help to predict how terrestrial plants interact with climate, soils, disturbance and competition for resources. We argue that there is untapped potential for the use of DGVMs in ecological and ecophysiological research. One fundamental barrier to realize this potential is that many researchers with relevant expertize (ecology, plant physiology, soil science, etc.) lack access to the technical resources or awareness of the research potential of DGVMs. Here we present the Land Sites Platform (LSP): new software that facilitates single-site simulations with the Functionally Assembled Terrestrial Ecosystem Simulator, an advanced DGVM coupled with the Community Land Model. The LSP includes a Graphical User Interface and an Application Programming Interface, which improve the user experience and lower the technical thresholds for installing these model architectures and setting up model experiments. The software is distributed via version-controlled containers; researchers and students can run simulations directly on their personal computers or servers, with relatively low hardware requirements, and on different operating systems. Version 1.0 of the LSP supports site-level simulations. We provide input data for 20 established geo-ecological observation sites in Norway and workflows to add generic sites from public global datasets. The LSP makes standard model experiments with default data easily achievable (e.g., for educational or introductory purposes) while retaining flexibility for more advanced scientific uses. We further provide tools to visualize the model input and output, including simple examples to relate predictions to local observations. The LSP improves access to land surface and DGVM modelling as a building block of community cyberinfrastructure that may inspire new avenues for mechanistic ecosystem research across disciplines.
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| 7. |
- Lett, Signe, et al.
(författare)
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Can bryophyte groups increase functional resolution in tundra ecosystems?
- 2022
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Ingår i: Arctic Science. - Ottawa : Canadian Science Publishing. - 2368-7460. ; 8:3, s. 609-637
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 8. |
- Rixen, C., et al.
(författare)
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Winters are changing: snow effects on Arctic and alpine tundra ecosystems
- 2022
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Ingår i: Arctic Science. - : Canadian Science Publishing. - 2368-7460. ; 8:3, s. 572-608
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Tidskriftsartikel (refereegranskat)abstract
- Snow is an important driver of ecosystem processes in cold biomes. Snow accumulation determines ground temperature, light conditions, and moisture availability during winter. It also affects the growing season's start and end, and plant access to moisture and nutrients. Here, we review the current knowledge of the snow cover's role for vegetation, plant-animal interactions, permafrost conditions, microbial processes, and biogeochemical cycling. We also compare studies of natural snow gradients with snow experimental manipulation studies to assess time scale difference of these approaches. The number of tundra snow studies has increased considerably in recent years, yet we still lack a comprehensive overview of how altered snow conditions will affect these ecosystems. Specifically, we found a mismatch in the timing of snowmelt when comparing studies of natural snow gradients with snow manipulations. We found that snowmelt timing achieved by snow addition and snow removal manipulations (average 7.9 days advance and 5.5 days delay, respectively) were substantially lower than the temporal variation over natural spatial gradients within a given year (mean range 56 days) or among years (mean range 32 days). Differences between snow study approaches need to be accounted for when projecting snow dynamics and their impact on ecosystems in future climates.
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