Department of Biology, Colorado State University, Fort Collins, Colorado, USA.
State Environmental Protection Key Laboratory of Wetland Ecology and Vegetation Restoration, School of Environment, Northeast Normal University, Changchun, China.
Glob Chang Biol. 2022 Mar;28(6):2124-2132. doi: 10.1111/gcb.16055. Epub 2022 Jan 3.
Free-living nematodes are one of the most diverse metazoan taxa in terrestrial ecosystems and are critical to the global soil carbon (C) cycling through their role in organic matter decomposition. They are highly dependent on water availability for movement, feeding, and reproduction. Projected changes in precipitation across temporal and spatial scales will affect free-living nematodes and their contribution to C cycling with unforeseen consequences. We experimentally reduced and increased growing season precipitation for 2 years in 120 field plots at arid, semiarid, and mesic grasslands and assessed precipitation controls on nematode genus diversity, community structure, and C footprint. Increasing annual precipitation reduced nematode diversity and evenness over time at all sites, but the mechanism behind these temporal responses differed for dry and moist grasslands. In arid and semiarid sites, there was a loss of drought-adapted rare taxa with increasing precipitation, whereas in mesic conditions increases in the population of predaceous taxa with increasing precipitation may have caused the observed reductions in dominant colonizer taxa and yielded the negative precipitation-diversity relationship. The effects of temporal changes in precipitation on all aspects of the nematode C footprint (respiration, production, and biomass C) were all dependent on the site (significant spatial × temporal precipitation interaction) and consistent with diversity responses at mesic, but not at arid and semiarid, grasslands. These results suggest that free-living nematode biodiversity and their C footprint will respond to climate change-driven shifts in water availability and that more frequent extreme wet years may accelerate decomposition and C turnover in semiarid and arid grasslands.
自由生活的线虫是陆地生态系统中最多样化的后生动物类群之一，通过在有机质分解中的作用，对全球土壤碳（C）循环至关重要。它们的运动、摄食和繁殖高度依赖于水分的可用性。在时间和空间尺度上预计会发生降水变化，这将影响自由生活的线虫及其对 C 循环的贡献，并带来无法预料的后果。我们在干旱、半干旱和湿润草地的 120 个野外样地中进行了为期 2 年的实验，减少和增加了生长季节的降水，评估了降水对线虫属多样性、群落结构和 C 足迹的控制作用。在所有地点，随着时间的推移，增加年降水量会降低线虫的多样性和均匀度，但在干旱和湿润草地中，这些时间响应的机制不同。在干旱和半干旱地区，随着降水的增加，适应干旱的稀有类群减少，而在湿润条件下，随着降水的增加，捕食性类群的数量增加，可能导致占优势的定殖者类群减少，从而产生了降水与多样性之间的负相关关系。降水时间变化对线虫 C 足迹（呼吸、生产和生物量 C）所有方面的影响都取决于地点（显著的空间 × 时间降水相互作用），与湿润草地的多样性响应一致，但与干旱和半干旱草地不一致。这些结果表明，自由生活的线虫生物多样性及其 C 足迹将对气候变化驱动的水分可用性变化做出响应，并且更频繁的极端湿润年份可能会加速半干旱和干旱草地的分解和 C 周转。
