Effect of interannual precipitation variability on dryland productivity: A global synthesis
Effect of interannual precipitation variability on dryland productivity: A global synthesis
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DOI：
10.1111/gcb.14480
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发表时间：
2019-01-01
影响因子：
11.6
通讯作者：
Sala, Osvaldo E.
中科院分区：
文献类型：
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作者：
Gherardi, Laureano A.;Sala, Osvaldo E.
气候变化评估预测，极端事件的频率增加，降水的变异性也会增加。然而，年际降水变化本身对生态系统功能的影响在很大程度上研究不足。在这里，我们报告的年际降水变化对全球旱地，其中包括沙漠，草原，灌丛，草地和草原的初级生产的影响，并覆盖约40%的陆地地球表面。我们使用了一个全球数据库，其中有43个数据集，这些数据集均匀分布在参数空间中，每个数据集至少有10年的数据。我们发现（a）在全球尺度上，降水变率对地上净初级生产力有负面影响。(b)预计2,100年的年际降水变化增加可能导致全球陆地碳汇减少12%。(c)降水年际变率对旱地生产力的影响沿降水梯度由正向负变化，变化趋势为沿着。干旱的网站，平均降水量低于300毫米/年的降水变化的增加作出积极的反应，而网站的平均降水量超过300毫米/年的负面反应。我们提出了三个补充机制来解释这一结果：（a）凹上和凹下的降水生产关系，在干旱与潮湿的系统，（B）在土壤剖面中的水分分布的转变，和（c）改变频率的积极和消极的遗产。我们的研究结果表明，增强降水变率将对全球旱地产生直接影响，可能会影响未来的陆地碳汇。
Climate-change assessments project increasing precipitation variability through increased frequency of extreme events. However, the effects of interannual precipitation variance per se on ecosystem functioning have been largely understudied. Here, we report on the effects of interannual precipitation variability on the primary production of global drylands, which include deserts, steppes, shrublands, grasslands, and prairies and cover about 40% of the terrestrial earth surface. We used a global database that has 43 datasets, which are uniformly distributed in parameter space and each has at least 10 years of data. We found (a) that at the global scale, precipitation variability has a negative effect on aboveground net primary production. (b) Expected increases in interannual precipitation variability for the year 2,100 may result in a decrease of up to 12% of the global terrestrial carbon sink. (c) The effect of precipitation interannual variability on dryland productivity changes from positive to negative along a precipitation gradient. Arid sites with mean precipitation under 300 mm/year responded positively to increases in precipitation variability, whereas sites with mean precipitation over 300 mm/year responded negatively. We propose three complementary mechanisms to explain this result: (a) concave-up and concave-down precipitation-production relationships in arid vs. humid systems, (b) shift in the distribution of water in the soil profile, and (c) altered frequency of positive and negative legacies. Our results demonstrated that enhanced precipitation variability will have direct impacts on global drylands that can potentially affect the future terrestrial carbon sink.