Climate change‐induced vegetation shifts lead to more ecological droughts despite projected rainfall increases in many global temperate drylands
Climate change‐induced vegetation shifts lead to more ecological droughts despite projected rainfall increases in many global temperate drylands
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DOI：
10.1111/gcb.13598
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发表时间：
2017-07
影响因子：
11.6
通讯作者：
B. Tietjen;D. Schlaepfer;J. Bradford;W. Lauenroth;S. Hall;M. Duniway;T. Hochstrasser;G. Jia;S. Munson;D. Pyke;S. Wilson
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作者：
B. Tietjen;D. Schlaepfer;J. Bradford;W. Lauenroth;S. Hall;M. Duniway;T. Hochstrasser;G. Jia;S. Munson;D. Pyke;S. Wilson
旱地分布在世界各地，特别容易受到气候变化的影响，因为旱地生态系统直接依赖于土壤水的供应，而土壤水的供应可能会随着气温的上升而变得越来越有限。气候变化将直接影响土壤水分供应和改变植物生物量，从而间接反馈土壤水分。因此，气候变化对土壤水分的直接和间接影响的净影响需要更好地了解。我们在全球各地的温带旱地生态系统中使用了生态水文模拟模型SOILWAT，以揭示直接气候变化影响和气候变化导致的额外间接植被变化对土壤水分可用性的贡献。我们模拟了16个气候模式在RCP 4.5和RCP 8.5下预测的本世纪末的当前和未来气候条件。我们确定了单独由于气候变化以及由于气候和植被的生长形式和生物量的综合变化而导致的水可获得性的变化。植被变化将在很大程度上加剧已经受到气候变化负面直接影响的地区的低土壤水可获得性(两种RCP情景给我们带来了质的相似的影响)。相比之下，在可能仅因气候变化而增加可用水的地区，植被变化将抵消由于截流导致的水损失增加所带来的增加。在只有一小部分地区，气候变化引起的植被变化可能导致可用水的净增加。这些结果表明，应对气候变化的植被变化可能会加剧干旱状况，并可能抑制降水增加的影响，即尽管一些地区降雨量较高，但仍会导致更多的生态干旱。我们的结果强调了在评估未来缺水生态系统中的土壤水分状况时，考虑气候变化对植被的间接影响的价值。
Drylands occur worldwide and are particularly vulnerable to climate change because 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 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, that is, 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.