Leaf litter diversity alters microbial activity, microbial abundances, and nutrient cycling in a subtropical forest ecosystem
Leaf litter diversity alters microbial activity, microbial abundances, and nutrient cycling in a subtropical forest ecosystem
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DOI：
10.1007/s10533-017-0353-6
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发表时间：
2017-07
期刊：
影响因子：
4
通讯作者：
Z. Pei;Katrin N. Leppert;D. Eichenberg;H. Bruelheide;P. Niklaus;F. Buscot;J. Gutknecht
中科院分区：
文献类型：
--
作者：
Z. Pei;Katrin N. Leppert;D. Eichenberg;H. Bruelheide;P. Niklaus;F. Buscot;J. Gutknecht
人类活动对森林生态系统中的树种组成和多样性都有影响。这反过来改变了植物凋落物的物种多样性和凋落物质量，这可能会对土壤微生物群落及其分解和养分循环功能产生级联效应。我们在中国东南部亚热带气候带进行了包括单一栽培、2种和4种混合栽培的凋落物分解实验，测试了微生物对凋落物物种多样性的响应。通过脂类分析评价土壤微生物群落组成，利用胞外酶活性和氮素总矿化速率评价微生物功能。凋落物物种多样性与菌根真菌和放线菌丰度呈正相关。另外，参与碳、磷吸收的酶活性和相对碳限制的酶指数仅在4种混合藻类中较高。这表明，只有在最高的多样性水平上，才达到了产酶的最低基本底物水平，或者极限更高。对凋落物多样性的响应也随着时间的推移而变化，其中磷酸酶对凋落物多样性的响应在分解早期最强，相对于其他营养物质的碳限用指数在分解后期表现出更强的响应。酶活性与第三个时间点的脂肪生物标志物数据和凋落物残留量相关，但酶活性与凋落物残留量之间的关系在其他时间点上不一致。我们的结论是，凋落物物种丰富度可能只会在多样性丧失的关键时段降低微生物的功能，而微生物的生长对逐渐减少的多样性更加敏感，它们之间或与生态系统功能之间没有明确的关系。凋落物多样性对土壤微生物生物量和酶活性的影响表明地上和地下群落的相互作用，以及环境条件对维持生态系统功能是重要的。
Human activities affect both tree species composition and diversity in forested ecosystems. This in turn alters the species diversity of plant litter and litter quality, which may have cascading effects on soil microbial communities and their functions for decomposition and nutrient cycling. We tested microbial responses to litter species diversity in a leaf litter decomposition experiment including monocultures, 2-, and 4-species mixtures in the subtropical climate zone of southeastern China. Soil microbial community composition was assessed by lipid analysis, and microbial functions were measured using extracellular enzyme activity and gross rates of nitrogen mineralization. We observed a positive relationship between litter species diversity and abundances of mycorrhizal fungi and actinomycetes. Alternatively, enzyme activities involved in carbon and phosphorus acquisition, and enzyme indices of relative carbon limitation, were higher only in the 4-species mixtures. This suggests that the minimum basal substrate level for enzyme production was reached, or that limitation was higher, at the highest diversity level only. Responses to litter diversity also changed over time, where phosphatase responses to litter diversity were strongest early in decomposition and the indices of carbon limitation relative to other nutrients showed stronger responses later in decomposition. Enzyme activities were related to lipid biomarker data and the mass of litter remaining at the third time point, but relationships between enzyme activity and the mass of litter remaining were not consistent across other time points. We conclude that litter species richness will likely only reduce microbial functions at key intervals of diversity loss while microbial growth is more sensitive to incremental diversity loss, with no clear relationships between them or to ecosystem functions. The observed litter diversity effects on soil microbial biomass and enzyme activity indicate interactions of aboveground and belowground communities, and together with environmental conditions they are important for maintaining ecosystem functions.