Contrasting ecosystem vegetation response in global drylands under drying and wetting conditions
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Increasing aridity is one major consequence of ongoing global climate change and is expected to cause widespread changes in key ecosystem attributes, functions, and dynamics. This is especially the case in naturally vulnerable ecosystems, such as drylands. While we have an overall understanding of past aridity trends, the linkage between temporal dynamics in aridity and dryland ecosystem responses remain largely unknown. Here, we examined recent trends in aridity over the past two decades within global drylands as a basis for exploring the response of ecosystem state variables associated with land and atmosphere processes (e.g., vegetation cover, vegetation functioning, soil water availability, land cover, burned area, and vapor-pressure deficit) to these trends. We identified five clusters, characterizing spatiotemporal patterns in aridity between 2000 and 2020. Overall, we observe that 44.5% of all areas are getting dryer, 31.6% getting wetter, and 23.8% have no trends in aridity. Our results show strongest correlations between trends in ecosystem state variables and aridity in clusters with increasing aridity, which matches expectations of systemic acclimatization of the ecosystem to a reduction in water availability/water stress. Trends in vegetation (expressed by leaf area index [LAI]) are affected differently by potential driving factors (e.g., environmental, and climatic factors, soil properties, and population density) in areas experiencing water-related stress as compared to areas not exposed to water-related stress. Canopy height for example, has a positive impact on trends in LAI when the system is stressed but does not impact the trends in non-stressed systems. Conversely, opposite relationships were found for soil parameters such as root-zone water storage capacity and organic carbon density. How potential driving factors impact dryland vegetation differently depending on water-related stress (or no stress) is important, for example within management strategies to maintain and restore dryland vegetation.
|Journal||Global Change Biology|
|Publication status||Published - 2023|
CA was funded by the European Space Agency (ESA) as part of the Climate Change Initiative (CCI) fellowship (ESA ESRIN/Contract No. 4000133555). AMA was supported by the Swedish Research Council (project number 2018–00430). TT was supported by the Swedish National Space Agency (SNSA 2021–00144 and 2021–00111) and FORMAS (Dnr. 2021–00644). SH is funded by the research projects DRYTIP (grant 37465) from VILLUM FONDEN and PerformLCA (Data+ Strategy 2023 funds) from University of Copenhagen and RF was supported by the research grant DeReEco (34306) from VILLUM FONDEN.
© 2023 The Authors. Global Change Biology published by John Wiley & Sons Ltd.
- aridity, drylands, ecosystem functioning, time-series analysis, vegetation, water-related stress