Global climate changes in temperature and precipitation are influencing the function of semiarid ecosystems, especially that of biocrust. Biocrust is the key biotic component in semiarid land and delivers multiple functions to belowground ecosystems. However, how biocrust affects belowground biota when temperature and water change remains unclear. We set a microcosm experiment to evaluate how soil micro‐food web responds to biocrust by changing air temperature and water content. Soil microbes and nematodes were sampled at different air temperatures (10 and 25°C) and soil water levels (4, 8, and 16% soil water content) under biocrust and bare soil. The results showed that biocrust highly increased soil microbe and nematode abundances compared with bare soil. Temperature change had no obvious effect on soil micro‐food web. Both microbial and nematode communities were strongly affected by soil water at 10°C under biocrust. Structural equation modeling analysis proved that soil pH and organic carbon were the two main factors that affected soil micro‐food channels under biocrust. Soil organic carbon affected bacterial channel and fungal channel. Soil pH affected soil bacterial channel and omnivores‐predators. Soil with 8% water content could provide the most stable habitat and soil environment to build a relatively complex and more reticulated soil micro‐food web. It can be concluded that colonization of biocrust could buffer temperature effect on soil micro‐food web. Additionally, appropriate increase in water could benefit the top‐down effect between nematodes and microbes under biocrust and could contribute to the resilience of semiarid ecosystems.

中文翻译：

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生物结皮调节水和温度对半干旱生态系统中土壤微生物和线虫群落的影响

全球温度和降水的气候变化正在影响半干旱生态系统的功能，尤其是生物结壳的功能。生物结皮是半干旱地区的关键生物成分，可为地下生态系统提供多种功能。然而，当温度和水的变化时，生物结皮如何影响地下生物区仍然不清楚。我们设置了一个微观实验，以评估土壤微食物网如何通过改变气温和水含量来响应生物结皮。在生物结皮和裸露土壤下，在不同的空气温度（10和25°C）和土壤水位（土壤水含量的4％，8％和16％）下对土壤微生物和线虫进行了采样。结果表明，与裸露土壤相比，生物结壳大大增加了土壤微生物和线虫的丰度。温度变化对土壤微食物网没有明显影响。微生物和线虫群落都受到生物结壳下10°C下土壤水的强烈影响。结构方程模型分析证明，土壤pH和有机碳是影响生物结皮下土壤微食物通道的两个主要因素。土壤有机碳影响细菌通道和真菌通道。土壤pH值影响土壤细菌通道和杂食性捕食者。含水量为8％的土壤可以提供最稳定的栖息地和土壤环境，以建立相对复杂且网状的土壤微食物网。可以得出结论，生物结皮的定殖可以缓冲温度对土壤微食物网的影响。此外，适当增加水量可以使线虫和微生物在生物结壳下产生自上而下的效果，并有助于半干旱生态系统的复原力。