Asymmetric responses of resource use efficiency to previous‐year precipitation in a semi‐arid grassland,Functional Ecology

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Asymmetric responses of resource use efficiency to previous‐year precipitation in a semi‐arid grassland
Functional Ecology ( IF 4.6 ) Pub Date : 2021-01-11 , DOI: 10.1111/1365-2435.13750
Juanjuan Han ₁ , Jiquan Chen ₂ , Weiyu Shi ₁ , Jian Song ₃ , Dafeng Hui ₄ , Jingyi Ru ₃ , Shiqiang Wan ₃

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Intensified inter‐annual fluctuations in precipitation could profoundly impact terrestrial ecosystems. However, how changes in previous‐year precipitation influence current ecosystem functioning (e.g. resource use efficiency) in semi‐arid regions remains unclear.
In this study, water use efficiency (WUE) and light use efficiency (LUE) were investigated in a multi‐year precipitation gradient experiment with seven treatment levels: 20%, 40% and 60% decreases and 20%, 40% and 60% increases in the amount of natural rainfall plus ambient precipitation. Plots receiving 60% less precipitation were representative of extreme dry years, whereas the other treatment levels fell within the normal year‐to‐year range in precipitation change. Measurements made in both the post‐treatment period (2013–2015) and the treatment period (2010–2012) provided an opportunity to quantify the legacy effects of precipitation on resource use efficiency (RUE).
Sensitivities of LUE to previous‐year precipitation were not changed among treatments in 2013. However, asymmetric responses of RUEs (i.e. WUE and LUE) to previous‐year precipitation were found in 2014–2015. WUE₂₀₁₄, WUE₂₀₁₅, LUE₂₀₁₄ and LUE₂₀₁₅ responded more strongly to previous normal decreased than increased precipitation. Importantly, they were more sensitive to previous extreme dry year (represented by 60% precipitation reduction) than normal wet year (represented by 60% precipitation increment). Above‐ground net primary productivity (ANPP) rather than resource absorption (R_uptake) drove these asymmetric responses of RUE, and biomass of grasses further explained the asymmetric responses of ANPP.
This study reveals the nonlinear responses of RUE to previous‐year precipitation and highlights that the legacy effects of precipitation on RUE can be ascribed to the changes in vegetation composition. Our findings can facilitate the prediction of the legacy effects of precipitation variation on grassland ecosystem functions in the future.

中文翻译：

半干旱草原资源利用效率对前一年降水的非对称响应

年际降水的加剧加剧可能对陆地生态系统产生深远影响。但是，尚不清楚半干旱地区前一年降水量的变化如何影响当前的生态系统功能（例如资源利用效率）。
在这项研究中，在多年降水梯度实验中研究了水的使用效率（WUE）和光的使用效率（LUE），该试验有七个处理级别：降低20％，40％和60％，降低20％，40％和60％自然降水量加上环境降水量的增加。降水减少60％的地块代表了极端干旱年份，而其他处理水平则在正常的年降水量范围内。在后处理期（2013–2015）和处理期（2010–2012）中进行的测量提供了量化降水对资源利用效率（RUE）的遗留影响的机会。
2013年，不同处理方法对LUE的前一年降水的敏感性没有变化。但是，2014-2015年发现RUE（即，WUE和LUE）对前一年降水的不对称响应。WUE ₂₀₁₄，WUE _2015年，LUE ₂₀₁₄和LUE _2015年的反应比较强烈，以之前的正常比增加降水减少。重要的是，它们对以前的极端干旱年份（以降水减少60％表示）比正常潮湿年份（以60％降水增加表示）更敏感。地上净初级生产力（ANPP）而非资源吸收（R_吸收）驱动了RUE的这些不对称响应，而草的生物量进一步解释了ANPP的不对称响应。
这项研究揭示了RUE对前一年降水的非线性响应，并强调了降水对RUE的遗留影响可以归因于植被组成的变化。我们的发现可以帮助预测未来降水变化对草地生态系统功能的遗留影响。

更新日期：2021-03-08

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