改变森林碳输入对土壤微生物磷脂脂肪酸群落组成的影响

Effects of alterations in carbon inputs on soil microbial phospholipid fatty acid community composition in forest

凋落物和植物根系是森林生态系统最重要的碳输入途径,深刻影响着土壤微生物的群落结构和功能,然而凋落物和植物根系如何影响微生物的群落结构以及其贡献仍然存在争议.以温带落叶阔叶林为研究对象,设置对照、凋落物移除、断根、断根+凋落物移除4种处理,探讨改变碳输入对土壤微生物磷脂脂肪酸群落组成的影响及内在机制.结果表明凋落物移除显著降低了微生物生物量碳和革兰氏阴性细菌比例,提高了革兰氏阳性细菌比例、革兰氏阳性细菌与阴性细菌比值、放线菌比例以及微生物生理压力,显著改变了微生物磷脂脂肪酸群落组成,而断根对微生物的群落结构没有明显影响.表明凋落物碳输入相比于植物根系对微生物磷脂脂肪酸群落组成起更重要的调控作用,凋落物主要通过改变土壤温度以及土壤碳、氮含量来调控微生物的群落组成.

Litter and plant roots are the most important carbon input pathways in forest ecosystem,which profoundly affect soil microbial community composition and related functions.However,how litter and plant roots affect microbial community composition and their relative contributions are still controversial.In this study,four treatments were established including control,litter removal,root exclusion,and root exclusion plus litter removal in a temperate broadleaved deciduous forest.The objective is to investigate the effects of changing carbon inputs on soil microbial phospholipid fatty acid community composition and its internal mechanism.The results showed that litter removal significantly decreased microbial biomass carbon and percentage of Gram-negative bacteria,increased percentage of Gram-positive bacteria,the ratio of Gram-positive/Gram-negative bacteria,percentage of actinomycetes,and microbial physiological stress,which significantly changed microbial phospholipid fatty acid community composition.However,root exclusion had no obvious impact on microbial community structure.This findings suggest that litter carbon input play a more important role in regulating microbial phospholipid fatty acid community composition than plant roots.Litter regulates microbial community composition mainly by altering soil temperature and soil carbon and nitrogen content.