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以川西高山林线交错带3种典型植被类型(针叶林、高山灌丛、高山草甸)下两个层次(LF层:新鲜凋落物层和发酵层;H层:腐殖质层)的凋落物为研究对象,分别模拟凋落物分解的前期和后期阶段,对凋落物分解过程中的纤维素酶活性及凋落物质量进行了研究。结果表明,凋落物分解前期的纤维素酶活性和纤维素含量均显著高于分解后期,但植被类型对LF和H层的纤维素含量的影响都不显著。双因素方差分析结果表明,凋落物分解阶段对纤维素酶活性和纤维素含量的影响比植被类型对纤维素酶活性和纤维素含量的影响更大。不同种类的纤维素酶活性在分解前期和分解后期受到不同因子的限制。凋落物分解前期,微晶纤维素酶和β-葡萄糖苷酶活性可能受N、P含量的限制,而羧甲基纤维素酶主要受底物纤维素含量控制;凋落物分解后期,羧甲基纤维素酶和β-葡萄糖苷酶可能受C、N含量的限制。生态化学计量学的理论预测,底物质量比C:N>27或C:P>186时会限制微生物生长,因此判断高山林线交错带凋落物微生物生物量和纤维素酶活性同时受到底物N、P的限制,尤其是高山草甸上微生物生物量在凋落物分解前期受到底物N、P的限制比分解后期更显著,这充分说明了底物质量调控着凋落物分解过程中的纤维素酶活性和微生物生物量。
The litter of three typical vegetation types (coniferous forests, alpine shrubs and alpine meadow) under two layers (LF layer: fresh litter layer and fermentation layer and H layer: humus layer) As the object of study, the early and late stages of litter decomposition were simulated respectively. The activities of cellulase and the litter quality during litter decomposition were studied. The results showed that the activities of cellulase and cellulose in the early litter decomposition were significantly higher than those in the later decomposition stage, but the vegetation types had no significant effect on the cellulose content in LF and H layers. The results of two-way ANOVA showed that the effect of litter decomposition stage on cellulase activity and cellulose content was more affected than the vegetation types on cellulase activity and cellulose content. Different kinds of cellulase activity are limited by different factors in the early stage of decomposition and late stage of decomposition. At the early stage of litter decomposition, the activity of microcrystalline cellulose and β-glucosidase may be limited by the content of N and P, while the content of carboxymethyl cellulose is mainly controlled by the cellulose content of the substrate. In the late stage of litter decomposition, Cellulase and beta-glucosidase may be limited by C, N content. The theoretical predictions of ecological stoichiometry suggest that microbial biomass growth may be restricted when the substrate mass ratio C: N> 27 or C: P> 186. Therefore, it can be concluded that microbial biomass and cellulase activity of litter in the ecotone N and P, especially the microbial biomass in alpine meadow was more restricted by the substrate N and P in the early stage of litter decomposition than that in the late stage of decomposition, which fully demonstrated that the substrate quality regulated the fiber in litter decomposition process Enzyme activity and microbial biomass.