川西亚高山森林土壤动物对杨树和箭竹凋落物分解过程中微生物群落的影响

为了解凋落物分解过程中碎屑食物链土壤动物与微生物的相互联系,本研究以川西亚高山森林杨树和箭竹凋落叶为对象,通过原位控制试验,于2016年4月至2018年4月采用磷脂脂肪酸(PLFAs)生物标记法,研究了土壤动物对两种凋落叶分解过程中微生物丰度、群落结构和多样性的影响.结果表明: 土壤动物的参与显著影响两个树种凋落叶分解过程中微生物PLFAs含量,降低了分解前240天的PLFAs含量,增加了分解360~480 d的PLFAs含量;土壤动物的参与降低了杨树分解过程中的真菌/细菌比值,增加了革兰氏阳性菌(G⁺)/革兰氏阴性菌(G^-)比值,对箭竹分解过程中真菌/细菌和G⁺/G^-比值的影响作用相反;两个树种凋落叶的微生物多样性和均匀性在分解的120 d和480 d维持着较高水平,在分解的360 d和720 d急剧降低,土壤动物的参与显著影响杨树凋落叶的微生物多样性和均匀性,但对箭竹影响不显著;土壤动物对凋落叶微生物PLFAs变化的影响随分解持续时间和树种变化存在差异.亚高山森林凋落物分解过程中土壤动物与微生物群落的相互作用随季节和树种变化具有变异性.

Effects of soil fauna on microbial community during litter decomposition of Populus simonii and Fargesia spathacea in the subalpine forest of western Sichuan,China.

To understand the relationship between soil fauna and microorganism in the detrital food chain during litter decomposition, leaf litters of poplar (Populus simonii) and fargesia (Fargesia spathacea) in a subalpine forest of western Sichuan were taken as study objects. Phospholipid fatty acid (PLFAs) biomarker method was used to determine the effects of soil fauna on the abundance, structure and diversity of microbial community during the decomposition of leaf litter of two species from April 2016 to April 2018 with in situ control experiment. The results showed that the presence of soil fauna significantly affected the microbial PLFAs content during the decomposition of both species, reducing the PLFAs content in the first 240 days and increasing the PLFAs content in the 360 to 480 days. Soil fauna participation reduced the ratio of fungi to bacteria in the decomposition of poplar litter, and increased the ratio of gram-positive bacteria (G⁺) to gram-negative bacteria (G^-), which had the opposite effect on the ratio of fungi/bacteria and G⁺/G^- in the decomposition of fargesia litter. Microbial diversity and evenness maintained a high level in 120^th and 480^th days of the decomposition, and decreased sharply in 360^th and 720^th days of decomposition. Soil fauna participation significantly affected microbial diversity and evenness of poplar litter, but it had no signifi-cant effect on fargesia litter. The effects of soil fauna on the changes of litter PLFAs content were different with the decomposition days and tree species. The interaction between soil fauna and microbial community during litter decomposition in subalpine forest varied with seasons and tree species.