Elevated nitrogen (N) deposition and increased precipitation often occur simultaneously, and have an interactive effect on terrestrial ecosystems, particularly in N-limited temperate forests. However, the effects of interactions between elevated N deposition and increased precipitation on soil communities are unclear. In the present study, we employed a novel approach to simulate N deposition and precipitation by applying N solution and water to the forest canopy, and explored how throughfall chemical properties and soil nematode communities responded to elevated N deposition and increased precipitation. We found that N deposition positively affected nematode communities by increasing the abundance of nematodes in some bacterivorous and fungivorous nematode groups. In contrast, increased precipitation suppressed bacterivorous and fungivorous nematodes, particularly of those guilds related to nutrient enrichment. Our results suggest that the positive effects of N deposition on nematode communities may be cancelled out by increased precipitation in temperate forest ecosystems, when elevated N deposition and increased precipitation occur simultaneously. This was not observed in previous studies simulating N deposition and precipitation, which was probably due to that they have been mostly based on understory manipulation without considering canopy processes.

升高的氮（N）沉积和增加的降水经常同时发生，并且对陆地生态系统产生交互作用，尤其是在氮有限的温带森林中。但是，尚不清楚氮沉降增加与降水增加之间的相互作用对土壤群落的影响。在本研究中，我们采用一种新颖的方法，通过向森林冠层中施用N溶液和水来模拟N的沉积和沉淀，并探讨了穿透性化学性质和土壤线虫群落如何对N沉积增加和降水增加做出响应。我们发现，N沉积通过增加某些细菌性和真菌性线虫组中线虫的丰度而对线虫群落产生积极影响。相反，降水增加抑制了细菌和真菌线虫，特别是与营养富集有关的行会。我们的结果表明，当氮沉降增加和降水增加同时发生时，温带森林生态系统中增加的降水可能抵消了氮沉积对线虫群落的积极影响。在先前的模拟N沉积和降水的研究中未观察到此现象，这可能是由于它们主要基于地下层操纵而不考虑冠层过程。当氮沉积增加和降水增加同时发生时。在以前的模拟N沉积和降水的研究中未观察到这一点，这可能是由于它们主要基于地下操纵而没有考虑冠层过程。当氮沉积增加和降水增加同时发生时。在以前的模拟N沉积和降水的研究中未观察到这一点，这可能是由于它们主要基于地下操纵而没有考虑冠层过程。