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Multi-year drought alters plant species composition more than productivity across northern temperate grasslands
Journal of Ecology ( IF 5.3 ) Pub Date : 2021-10-22 , DOI: 10.1111/1365-2745.13796 Amgaa Batbaatar 1, 2 , Cameron N. Carlyle 2 , Edward W. Bork 2 , Scott X. Chang 3 , James F. Cahill 1
中文翻译：
多年干旱对北部温带草原的植物物种组成的改变比对生产力的影响更大
更新日期：2021-10-22
Journal of Ecology ( IF 5.3 ) Pub Date : 2021-10-22 , DOI: 10.1111/1365-2745.13796 Amgaa Batbaatar 1, 2 , Cameron N. Carlyle 2 , Edward W. Bork 2 , Scott X. Chang 3 , James F. Cahill 1
Affiliation
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- The occurrence of multi-year drought is predicted to increase globally with climate change. However, it is unclear whether drought effects on ecosystems are progressive through time.
- Here, we experimentally reduced growing season precipitation (GSP) by 45% at seven North American temperate grasslands for four consecutive years to determine the following: (a) whether the effects of reduced precipitation on plant community structure and biomass components (shoot, root, litter) are compounding over time; (b) whether prior year climatic and soil conditions influence subsequent drought impacts on plant community structure and biomass components; and (c) whether the effects of reduced precipitation on individual ecosystem components are related to one another.
- Across the seven field sites, we observed neither consistent nor progressive effects of reduced precipitation on any biomass component during the experiment, despite having extreme drought conditions imposed for four consecutive years. Relative to the ambient treatment, above-ground net primary productivity (ANPP) declined in response to drought during the early years of the experiment but increased above the ambient treatment in the fourth year, while root and litter biomass were stable across the sites throughout the study. Similarly, graminoid cover decreased initially but recovered by the final year of the experiment, contributing to observed differences in species composition between treatments across sites. Compositional changes were not associated with any declines in species richness or evenness. Divergent responses among years were not driven by lag effects based on prior year climatic and soil conditions. Furthermore, precipitation effects on ecosystem components were largely independent as we found only two positive links: between ANPP and plant species richness, and between species evenness and composition.
- Synthesis. Overall, our results suggest that these northern grasslands are relatively resistant to short-term multi-year drought in the context of supporting plant diversity and biomass production.
中文翻译：
多年干旱对北部温带草原的植物物种组成的改变比对生产力的影响更大
- 预计随着气候变化，全球多年干旱的发生率将增加。然而，尚不清楚干旱对生态系统的影响是否随着时间的推移而渐进。
- 在这里，我们连续四年在七个北美温带草原实验性地减少了 45% 的生长季节降水 (GSP)，以确定以下内容：(a) 降水减少是否对植物群落结构和生物量成分（芽、根、垃圾）随着时间的推移而复合；(b) 前一年的气候和土壤条件是否会影响随后干旱对植物群落结构和生物量成分的影响；(c) 降水减少对个别生态系统组成部分的影响是否相互关联。
- 在七个田间地点，我们在实验期间既没有观察到降水减少对任何生物量成分的一致影响，也没有观察到渐进影响，尽管连续四年施加了极端干旱条件。相对于环境处理，地上部净初级生产力 (ANPP) 在实验的最初几年因干旱而下降，但在第四年高于环境处理，而根系和凋落物生物量在整个试验过程中在整个地点保持稳定学习。同样，禾本科植物覆盖率最初减少，但在实验的最后一年恢复，这导致在不同地点的处理之间观察到物种组成的差异。组成变化与物种丰富度或均匀度的任何下降无关。年份之间的不同反应不是由基于前一年气候和土壤条件的滞后效应驱动的。此外，降水对生态系统成分的影响在很大程度上是独立的，因为我们发现只有两个积极的联系：ANPP 与植物物种丰富度之间，以及物种均匀度和组成之间。
- 合成。总体而言，我们的研究结果表明，在支持植物多样性和生物量生产的背景下，这些北方草原对短期多年干旱具有相对抵抗力。
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