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Acceleration of global vegetation greenup from combined effects of climate change and human land management.

https://arctichealth.org/en/permalink/ahliterature297897
Source
Glob Chang Biol. 2018 11; 24(11):5484-5499
Publication Type
Journal Article
Research Support, Non-U.S. Gov't
Date
11-2018
Author
Lanhui Wang
Feng Tian
Yuhang Wang
Zhendong Wu
Guy Schurgers
Rasmus Fensholt
Author Affiliation
Department of Geosciences and Natural Resource Management, University of Copenhagen, Copenhagen, Denmark.
Source
Glob Chang Biol. 2018 11; 24(11):5484-5499
Date
11-2018
Language
English
Publication Type
Journal Article
Research Support, Non-U.S. Gov't
Keywords
Agriculture
Climate change
Forestry
Humans
Plant Development
Remote Sensing Technology
Urbanization
Abstract
Global warming and human land management have greatly influenced vegetation growth through both changes in spring phenology and photosynthetic primary production. This will presumably impact the velocity of vegetation greenup (Vgreenup, the daily rate of changes in vegetation productivity during greenup period), yet little is currently known about the spatio-temporal patterns of Vgreenup of global vegetation. Here, we define Vgreenup as the ratio of the amplitude of greenup (Agreenup) to the duration of greenup (Dgreenup) and derive global Vgreenup from 34-year satellite leaf area index (LAI) observations to study spatio-temporal dynamics of Vgreenup at the global, hemispheric, and ecosystem scales. We find that 19.9% of the pixels analyzed (n = 1,175,453) experienced significant trends toward higher greenup rates by an average of 0.018 m2  m-2  day-1 for 1982-2015 as compared to 8.6% of pixels with significant negative trends (p 
PubMed ID
29963745 View in PubMed
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Acceleration of global vegetation greenup from combined effects of climate change and human land management.

https://arctichealth.org/en/permalink/ahliterature292666
Source
Glob Chang Biol. 2018 Jul 02; :
Publication Type
Journal Article
Date
Jul-02-2018
Author
Lanhui Wang
Feng Tian
Yuhang Wang
Zhendong Wu
Guy Schurgers
Rasmus Fensholt
Author Affiliation
Department of Geosciences and Natural Resource Management, University of Copenhagen, Øster Voldgade 10, DK-1350, Copenhagen, Denmark.
Source
Glob Chang Biol. 2018 Jul 02; :
Date
Jul-02-2018
Language
English
Publication Type
Journal Article
Abstract
Global warming and human land management have greatly influenced vegetation growth through both changes in spring phenology and photosynthetic primary production. This will presumably impact the velocity of vegetation greenup (Vgreenup, the daily rate of changes in vegetation productivity during greenup period), yet little is currently known about the spatio-temporal patterns of Vgreenup of global vegetation. Here, we define Vgreenup as the ratio of the amplitude of greenup (Agreenup) to the duration of greenup (Dgreenup) and derive global Vgreenup from 34-year satellite leaf area index (LAI) observations to study spatio-temporal dynamics of Vgreenup at the global, hemispheric and ecosystem scales. We find that 19.9% of the pixels analyzed (n = 1175453) experienced significant trends toward higher greenup rates by an average of 0.018 m2 m-2 day-1 for 1982-2015 as compared to 8.6% of pixels with significant negative trends (P
PubMed ID
29963745 View in PubMed
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Drivers of dissolved organic carbon export in a subarctic catchment: Importance of microbial decomposition, sorption-desorption, peatland and lateral flow.

https://arctichealth.org/en/permalink/ahliterature287448
Source
Sci Total Environ. 2017 Dec 04;622-623:260-274
Publication Type
Article
Date
Dec-04-2017
Author
Jing Tang
Alla Y Yurova
Guy Schurgers
Paul A Miller
Stefan Olin
Benjamin Smith
Matthias B Siewert
David Olefeldt
Petter Pilesjö
Anneli Poska
Source
Sci Total Environ. 2017 Dec 04;622-623:260-274
Date
Dec-04-2017
Language
English
Publication Type
Article
Abstract
Tundra soils account for 50% of global stocks of soil organic carbon (SOC), and it is expected that the amplified climate warming in high latitude could cause loss of this SOC through decomposition. Decomposed SOC could become hydrologically accessible, which increase downstream dissolved organic carbon (DOC) export and subsequent carbon release to the atmosphere, constituting a positive feedback to climate warming. However, DOC export is often neglected in ecosystem models. In this paper, we incorporate processes related to DOC production, mineralization, diffusion, sorption-desorption, and leaching into a customized arctic version of the dynamic ecosystem model LPJ-GUESS in order to mechanistically model catchment DOC export, and to link this flux to other ecosystem processes. The extended LPJ-GUESS is compared to observed DOC export at Stordalen catchment in northern Sweden. Vegetation communities include flood-tolerant graminoids (Eriophorum) and Sphagnum moss, birch forest and dwarf shrub communities. The processes, sorption-desorption and microbial decomposition (DOC production and mineralization) are found to contribute most to the variance in DOC export based on a detailed variance-based Sobol sensitivity analysis (SA) at grid cell-level. Catchment-level SA shows that the highest mean DOC exports come from the Eriophorum peatland (fen). A comparison with observations shows that the model captures the seasonality of DOC fluxes. Two catchment simulations, one without water lateral routing and one without peatland processes, were compared with the catchment simulations with all processes. The comparison showed that the current implementation of catchment lateral flow and peatland processes in LPJ-GUESS are essential to capture catchment-level DOC dynamics and indicate the model is at an appropriate level of complexity to represent the main mechanism of DOC dynamics in soils. The extended model provides a new tool to investigate potential interactions among climate change, vegetation dynamics, soil hydrology and DOC dynamics at both stand-alone to catchment scales.
PubMed ID
29216467 View in PubMed
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Modelling past and future peatland carbon dynamics across the pan-Arctic.

https://arctichealth.org/en/permalink/ahliterature306381
Source
Glob Chang Biol. 2020 07; 26(7):4119-4133
Publication Type
Journal Article
Date
07-2020
Author
Nitin Chaudhary
Sebastian Westermann
Shubhangi Lamba
Narasinha Shurpali
A Britta K Sannel
Guy Schurgers
Paul A Miller
Benjamin Smith
Author Affiliation
Department of Geosciences, University of Oslo, Oslo, Norway.
Source
Glob Chang Biol. 2020 07; 26(7):4119-4133
Date
07-2020
Language
English
Publication Type
Journal Article
Keywords
Arctic Regions
Carbon
Carbon Cycle
Ecosystem
Permafrost
Abstract
The majority of northern peatlands were initiated during the Holocene. Owing to their mass imbalance, they have sequestered huge amounts of carbon in terrestrial ecosystems. Although recent syntheses have filled some knowledge gaps, the extent and remoteness of many peatlands pose challenges to developing reliable regional carbon accumulation estimates from observations. In this work, we employed an individual- and patch-based dynamic global vegetation model (LPJ-GUESS) with peatland and permafrost functionality to quantify long-term carbon accumulation rates in northern peatlands and to assess the effects of historical and projected future climate change on peatland carbon balance. We combined published datasets of peat basal age to form an up-to-date peat inception surface for the pan-Arctic region which we then used to constrain the model. We divided our analysis into two parts, with a focus both on the carbon accumulation changes detected within the observed peatland boundary and at pan-Arctic scale under two contrasting warming scenarios (representative concentration pathway-RCP8.5 and RCP2.6). We found that peatlands continue to act as carbon sinks under both warming scenarios, but their sink capacity will be substantially reduced under the high-warming (RCP8.5) scenario after 2050. Areas where peat production was initially hampered by permafrost and low productivity were found to accumulate more carbon because of the initial warming and moisture-rich environment due to permafrost thaw, higher precipitation and elevated CO2 levels. On the other hand, we project that areas which will experience reduced precipitation rates and those without permafrost will lose more carbon in the near future, particularly peatlands located in the European region and between 45 and 55°N latitude. Overall, we found that rapid global warming could reduce the carbon sink capacity of the northern peatlands in the coming decades.
PubMed ID
32239563 View in PubMed
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Separating direct and indirect effects of rising temperatures on biogenic volatile emissions in the Arctic.

https://arctichealth.org/en/permalink/ahliterature304033
Source
Proc Natl Acad Sci U S A. 2020 12 22; 117(51):32476-32483
Publication Type
Journal Article
Research Support, Non-U.S. Gov't
Date
12-22-2020
Author
Riikka Rinnan
Lars L Iversen
Jing Tang
Ida Vedel-Petersen
Michelle Schollert
Guy Schurgers
Author Affiliation
Terrestrial Ecology Section, Department of Biology, University of Copenhagen, DK-2100 Copenhagen Ø, Denmark; riikkar@bio.ku.dk.
Source
Proc Natl Acad Sci U S A. 2020 12 22; 117(51):32476-32483
Date
12-22-2020
Language
English
Publication Type
Journal Article
Research Support, Non-U.S. Gov't
Abstract
Volatile organic compounds (VOCs) are released from biogenic sources in a temperature-dependent manner. Consequently, Arctic ecosystems are expected to greatly increase their VOC emissions with ongoing climate warming, which is proceeding at twice the rate of global temperature rise. Here, we show that ongoing warming has strong, increasing effects on Arctic VOC emissions. Using a combination of statistical modeling on data from several warming experiments in the Arctic tundra and dynamic ecosystem modeling, we separate the impacts of temperature and soil moisture into direct effects and indirect effects through vegetation composition and biomass alterations. The indirect effects of warming on VOC emissions were significant but smaller than the direct effects, during the 14-y model simulation period. Furthermore, vegetation changes also cause shifts in the chemical speciation of emissions. Both direct and indirect effects result in large geographic differences in VOC emission responses in the warming Arctic, depending on the local vegetation cover and the climate dynamics. Our results outline complex links between local climate, vegetation, and ecosystem-atmosphere interactions, with likely local-to-regional impacts on the atmospheric composition.
PubMed ID
33257556 View in PubMed
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