Climate change-induced vegetation shifts lead to more ecological droughts despite projected rainfall increases in many global temperate drylands

Global Change Biology
By: , and 

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Abstract

Drylands occur world-wide and are particularly vulnerable to climate change since dryland ecosystems depend directly on soil water availability that may become increasingly limited as temperatures rise. Climate change will both directly impact soil water availability, and also change plant biomass, with resulting indirect feedbacks on soil moisture. Thus, the net impact of direct and indirect climate change effects on soil moisture requires better understanding.

We used the ecohydrological simulation model SOILWAT at sites from temperate dryland ecosystems around the globe to disentangle the contributions of direct climate change effects and of additional indirect, climate change-induced changes in vegetation on soil water availability. We simulated current and future climate conditions projected by 16 GCMs under RCP 4.5 and RCP 8.5 for the end of the century. We determined shifts in water availability due to climate change alone and due to combined changes of climate and the growth form and biomass of vegetation.

Vegetation change will mostly exacerbate low soil water availability in regions already expected to suffer from negative direct impacts of climate change (with the two RCP scenarios giving us qualitatively similar effects). By contrast, in regions that will likely experience increased water availability due to climate change alone, vegetation changes will counteract these increases due to increased water losses by interception. In only a small minority of locations, climate change induced vegetation changes may lead to a net increase in water availability. These results suggest that changes in vegetation in response to climate change may exacerbate drought conditions and may dampen the effects of increased precipitation, i.e. leading to more ecological droughts despite higher precipitation in some regions. Our results underscore the value of considering indirect effects of climate change on vegetation when assessing future soil moisture conditions in water-limited ecosystems.

Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Climate change-induced vegetation shifts lead to more ecological droughts despite projected rainfall increases in many global temperate drylands
Series title Global Change Biology
DOI 10.1111/gcb.13598
Volume 23
Issue 7
Year Published 2017
Language English
Publisher Wiley
Contributing office(s) John Wesley Powell Center for Analysis and Synthesis, Forest and Rangeland Ecosystem Science Center
Description 12 p.
First page 2743
Last page 2754