Department of Biology, Colorado State University, Fort Collins, CO, 80523, USA; Natural Resource Ecology Laboratory, Colorado State University, Fort Collins, CO, 80523, USA.
Glob Chang Biol. 2014 Aug;20(8):2631-43. doi: 10.1111/gcb.12522. Epub 2014 Apr 30.
Climate change will result in reduced soil water availability in much of the world either due to changes in precipitation or increased temperature and evapotranspiration. How communities of mites and nematodes may respond to changes in moisture availability is not well known, yet these organisms play important roles in decomposition and nutrient cycling processes. We determined how communities of these organisms respond to changes in moisture availability and whether common patterns occur along fine-scale gradients of soil moisture within four individual ecosystem types (mesic, xeric and arid grasslands and a polar desert) located in the western United States and Antarctica, as well as across a cross-ecosystem moisture gradient (CEMG) of all four ecosystems considered together. An elevation transect of three sampling plots was monitored within each ecosystem and soil samples were collected from these plots and from existing experimental precipitation manipulations within each ecosystem once in fall of 2009 and three times each in 2010 and 2011. Mites and nematodes were sorted to trophic groups and analyzed to determine community responses to changes in soil moisture availability. We found that while both mites and nematodes increased with available soil moisture across the CEMG, within individual ecosystems, increases in soil moisture resulted in decreases to nematode communities at all but the arid grassland ecosystem; mites showed no responses at any ecosystem. In addition, we found changes in proportional abundances of mite and nematode trophic groups as soil moisture increased within individual ecosystems, which may result in shifts within soil food webs with important consequences for ecosystem functioning. We suggest that communities of soil animals at local scales may respond predictably to changes in moisture availability regardless of ecosystem type but that additional factors, such as climate variability, vegetation composition, and soil properties may influence this relationship over larger scales.
气候变化将导致世界上许多地区的土壤水分供应减少，原因要么是降水变化，要么是温度和蒸散增加。螨类和线虫群落如何应对水分可用性的变化尚不清楚，但这些生物在分解和养分循环过程中起着重要作用。我们确定了这些生物群落对水分可用性变化的反应方式，以及它们是否在四个单独的生态系统类型（湿润、干旱和干旱草原以及极地沙漠）内的土壤水分细尺度梯度以及在所有四个生态系统一起考虑的跨生态系统水分梯度（CEMG）内出现常见模式。在每个生态系统内，监测了三个采样点的海拔剖面，从这些样点和每个生态系统内现有的实验降水处理中采集土壤样本，2009 年秋季采集一次，2010 年和 2011 年每年采集三次。螨类和线虫被分类为营养组进行分析，以确定群落对土壤水分可用性变化的反应。我们发现，虽然螨类和线虫都随着 CEMG 中的可用土壤水分而增加，但在单个生态系统内，土壤水分增加导致除干旱草原生态系统外，所有生态系统的线虫群落减少；螨类在任何生态系统中都没有反应。此外，我们发现随着单个生态系统内土壤水分的增加，螨类和线虫营养组的比例发生变化，这可能导致土壤食物网内发生变化，对生态系统功能产生重要影响。我们认为，无论生态系统类型如何，局部尺度上的土壤动物群落可能会对水分可用性的变化做出可预测的反应，但其他因素，如气候变异性、植被组成和土壤特性，可能会在较大尺度上影响这种关系。
