The bottom-up effects of vegetation have been documented to be strong drivers of the soil food web structure and functioning in temperate forests. However, how the forest type affects the stability of the soil food web is not well known. In the Ziwuling forest region of the Loess Plateau, we selected three typical forests, Pinus tabuliformis Carrière (PT), Betula platyphylla Sukaczev (BP), and Quercus liaotungensis Koidz. (QL), to investigate the soil nematode community characteristics in the dry (April) and rainy (August) season, and analyzed their relationships with the soil properties. The results showed that the characteristics of the soil nematode communities and their seasonal variations differed markedly among the forest types. Compared to P. tabuliformis (PT), the B. platyphylla (BP) and Q. liaotungensis (QL) forests had higher plant diversity and more easily decomposed litters, which were more effective for improving the soil resource availability, thus, leading to more beneficial effects on the soil nematode community. In both the dry and rainy season, the soil nematode abundance was the highest in the BP forest. The Shannon–Wiener diversity index (H’), Pielou’s evenness index (J’), and nematode channel ratio index (NCR) were higher, while the Simpson dominance index (λ) and plant parasite index (PPI) were lower, in the BP and QL forests compared with in the PT forest. From the dry to rainy season, the total nematode abundance and the abundance of fungivores, bacterivores, and omnivore-predators, significantly increased in the QL and PT forests, and the values of the Wasilewska index (WI), maturity index (MI), H’, J’, λ, and NCR showed the most significant seasonal variability in the PT forest, which were mainly driven by changes in the soil labile C and N and the moisture content between the two seasons. Generally, the seasonal stability of the soil nematode communities was the highest in the BP forest and the poorest in the PT forest, probably due to variations in the plant diversity. Our results suggest the importance of tree species and diversity as bottom-up regulating factors of the soil food web structure, function, and seasonal stability, which has important implications for sustainable forest management in the Loess Plateau and other temperate regions.

中文翻译：

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黄土高原不同温带森林土壤线虫群落的季节性稳定性及其与环境因子的关系

据记录，植被的自下而上效应是温带森林土壤食物网结构和功能的强大驱动力。然而，森林类型如何影响土壤食物网的稳定性尚不清楚。在黄土高原子午岭林区，我们选择了三个典型的森林，油松卡里尔（ PT），白桦Sukaczev （ BP）和辽东栎三叶木通。（QL），以调查旱季（4月）和雨季（8月）的土壤线虫群落特征，并分析它们与土壤特性的关系。结果表明，不同类型的森林土壤线虫群落特征及其季节变化存在显着差异。与油松（PT）相比，白桦（BP）和辽东栎（QL）森林具有更高的植物多样性和更易分解的凋落物，对提高土壤资源的利用效率更高，从而带来了更多的收获。对土壤线虫群落的有益影响。在干旱和雨季，BP森林的土壤线虫丰度最高。香农-维纳多样性指数（H'），与PT相比，BP和QL森林的Pielou均匀度指数（J'）和线虫通道比指数（NCR）较高，而Simpson优势指数（λ）和植物寄生虫指数（PPI）较低。森林。从干旱到雨季，QL和PT森林中的线虫总数和真菌，噬菌体和杂食性食肉动物的总数显着增加，而Wasilewska指数（WI），成熟度指数（MI），H'，J'，λ和NCR在PT森林中表现出最显着的季节性变化，这主要是由土壤不稳定的C和N以及两个季节之间的水分含量的变化驱动的。通常，土壤线虫群落的季节稳定性在BP森林中最高，而在PT森林中最差，这可能是由于植物多样性的变化所致。我们的结果表明，树种和多样性作为土壤食物网结构，功能和季节稳定性的自下而上调节因素的重要性，这对黄土高原和其他温带地区的可持续森林管理具有重要意义。