School of Life Sciences, International Joint Research Laboratory for Global Change Ecology, Henan University, Kaifeng, Henan, China.
Department of Biological Sciences, Tennessee State University, Nashville, TN, USA.
Glob Chang Biol. 2018 Mar;24(3):1001-1011. doi: 10.1111/gcb.13941. Epub 2017 Nov 27.
Changing precipitation regimes could have profound influences on carbon (C) cycle in the biosphere. However, how soil C release from terrestrial ecosystems responds to changing seasonal distribution of precipitation remains unclear. A field experiment was conducted for 4 years (2013-2016) to examine the effects of altered precipitation distributions in the growing season on soil respiration in a temperate steppe in the Mongolian Plateau. Over the 4 years, both advanced and delayed precipitation peaks suppressed soil respiration, and the reductions mainly occurred in August. The decreased soil respiration could be primarily attributable to water stress and subsequently limited plant growth (community cover and belowground net primary productivity) and soil microbial activities in the middle growing season, suggesting that precipitation amount in the middle growing season is more important than that in the early, late, or whole growing seasons in regulating soil C release in grasslands. The observations of the additive effects of advanced and delayed precipitation peaks indicate semiarid grasslands will release less C through soil respiratory processes under the projected seasonal redistribution of precipitation in the future. Our findings highlight the potential role of intra-annual redistribution of precipitation in regulating ecosystem C cycling in arid and semiarid regions.
降水格局的改变可能会对生物圈中的碳（C）循环产生深远影响。然而，陆地生态系统中土壤 C 的释放如何响应降水季节分布的改变仍不清楚。本研究在蒙古高原温带草原进行了为期 4 年（2013-2016 年）的野外实验，以检验生长季降水分布改变对土壤呼吸的影响。在这 4 年中，提前和延迟的降水峰值均抑制了土壤呼吸，且这种减少主要发生在 8 月。土壤呼吸的减少主要归因于水分胁迫，进而限制了植物在生长中期的生长（群落盖度和地下净初级生产力）和土壤微生物活性，这表明生长中期的降水对调节草原土壤 C 释放的重要性大于早期、晚期或整个生长季的降水。提前和延迟降水峰值的累加效应表明，在未来预期的降水季节性再分配下，半干旱草地通过土壤呼吸过程释放的 C 将减少。本研究结果强调了年内降水再分配在干旱和半干旱地区调节生态系统 C 循环中的潜在作用。
