Abstract：
Plant litter is known to affect soil, community, and ecosystem properties. However, we know little about the capacity of litter to modulate grassland responses to climate change. Using a 7-yr litter removal experiment in a semiarid grassland, here we examined how litter removal interacts with a 2-yr drought to affect soil environments, plant community composition, and ecosystem function. Litter loss exacerbates the negative impacts of drought on grasslands. Litter removal increased soil temperature but reduced soil moisture and nitrogen mineralization, which substantially increased the negative impacts of drought on primary productivity and the abundance of perennial rhizomatous graminoids. Moreover, complete litter removal shifted plant community composition from grass-dominated to forb-dominated and reduced species and functional group asynchrony, resulting in lower ecosystem temporal stability. Our results suggest that ecological processes that lead to reduction in litter, such as burning, grazing, and haying, may render ecosystems more vulnerable and impair the capacity of grasslands to withstand drought events.
摘要：
已知植物凋落物会影响土壤，社区,和生态系统属性。然而,我们对凋落物调节草地对气候变化的响应的能力知之甚少。在半干旱草地上进行了为期7年的凋落物去除实验，在这里，我们研究了凋落物去除如何与两年干旱相互作用以影响土壤环境，植物群落组成，和生态系统功能。凋落物损失加剧了干旱对草原的负面影响。凋落物去除增加了土壤温度，但降低了土壤水分和氮矿化，这大大增加了干旱对初级生产力和多年生根茎类线虫的负面影响。此外，完全清除凋落物将植物群落组成从草类为主转变为forb为主和减少的物种和功能群异步，导致生态系统时间稳定性降低。我们的结果表明，导致凋落物减少的生态过程，比如燃烧，放牧,还有Haying,可能会使生态系统更加脆弱，并削弱草原抵御干旱事件的能力。
