This study aimed to elucidate the ecological role of cyanobacteria-dominated crusts on soil enzymes activities along a precipitation gradient. Results showed that proteins and polysaccharides contents of cyanobacterial-dominated crusts changed significantly among nine sample sites. Meanwhile, proteins and polysaccharides displayed a downward trend with increasing thickness and decreased with increasing mean annual temperature, while these two first increased, and then decreased with increasing chlorophyll a. The pronounced variations of polysaccharides and proteins could be explained by the shift in cyanobacteria species composition due to the discrepancy of succession stage at the regional scale. Activities of soil enzymes decreased with depth and varied significantly among sample sites. Redundancy analysis showed that soil enzymes activities in 0–2 cm were mainly explained by microbial biomass, polysaccharides, and soil organic carbon, and those in 2–5 cm were mainly influenced by microbial biomass and climate, while those in 5–10 cm were mainly affected by climate. The results highlighted the intrinsic involvement of microbes in shallower soil (0–5 cm) after the establishment of crusts and proved the effect of polysaccharides on surface soil (0–2 cm) enzymes activities. The strengthened effect of climate on soil enzymes activities in depths manifested the water availability and temperature would restrict soil microbial activity. Therefore, we concluded that the response of soil enzymes activities beneath the cyanobacteria-dominated crusts is depth related. Overall, our findings will provide a better knowledge of cyanobacteria-dominated crusts properties at the regional scale, and its effects on soil enzymes activities can replenish the understanding of cyanobacteria-dominated crusts on biogeochemical processes.

中文翻译：

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土壤酶对沿降水梯度蓝藻占主导地位的结皮的深度相关响应

本研究旨在阐明以蓝藻为主的结皮对沿降水梯度的土壤酶活性的生态作用。结果表明，9个样点间以蓝藻为主的结壳蛋白质和多糖含量变化显着。同时，蛋白质和多糖随着厚度的增加呈下降趋势，随着年平均气温的升高呈下降趋势，而这两者随着叶绿素a的增加呈先上升后下降的趋势。. 由于区域尺度上演替阶段的差异，蓝藻物种组成的变化可以解释多糖和蛋白质的显着变化。土壤酶的活性随着深度的增加而降低，并且在样本点之间存在显着差异。冗余分析表明，0~2 cm土壤酶活性主要由微生物生物量、多糖和土壤有机碳解释，2~5 cm主要受微生物生物量和气候影响，5~10 cm主要受微生物生物量和气候影响。主要受气候影响。结果突出了地壳形成后微生物在浅层土壤（0-5 cm）中的内在参与，并证明了多糖对表层土壤（0-2 cm）酶活性的影响。气候对深层土壤酶活性的强化作用表明，水分的有效性和温度会限制土壤微生物的活动。因此，我们得出结论，蓝藻占主导地位的地壳下土壤酶活性的响应与深度相关。总体而言，我们的研究结果将更好地了解区域尺度上以蓝藻为主的结皮特性，其对土壤酶活性的影响可以补充对蓝藻为主的结皮对生物地球化学过程的理解。