不同抚育措施对川西亚高山云杉人工林土壤微生物群落结构的短期影响

Short-term effects of different tending measures on soil microbial communities in subalpine spruce plantations of western Sichuan

土壤微生物作为森林生态系统的重要组成部分,能够对外部干扰作出快速反应,是评价人类活动对土壤性质和相关功能影响的敏感指标.在川西亚高山地区云杉人工林中开展不同强度的间伐(对照,0%;T1,10%;T2,20%)和修枝(对照,0%;P1,1 m修枝;T2,2 m修枝)抚育措施,分析不同抚育措施下土壤微生物群落结构变化特征及其影响因素,探讨土壤微生物群落对抚育措施的快速响应机制.结果表明:(1)除真菌丰富度外,土壤微生物群落多样性不受疏伐和修枝交互作用的影响.土壤细菌丰富度、多样性和均匀度随间伐强度的增大而降低,而真菌的多样性无显著变化.1 m修枝的抚育方式显著增加了土壤细菌群落的多样性.(2)疏伐和修枝措施对土壤细菌中的芽单胞菌门和浮霉菌门具有显著的交互作用,但各个优势门类群的相对丰度在不同疏伐和修枝强度间无显著差异.抚育措施对真菌优势类群相对丰度的影响更为显著,疏伐后子囊菌门相对丰度下降,而担子菌门显著增加.(3)毛管孔隙度、速效钾和速效磷是影响土壤细菌类群丰富度的主要影响因子;而速效钾是影响真菌类群丰富度的主要因子.在土壤细菌群落中,浮霉菌门和芽单胞菌门更容易受土壤环境变化的影响.因此,疏伐和修枝抚育措施能够影响土壤微生物群落多样性,改变土壤真菌优势类群丰富度,研究结果对云杉人工林健康经营及模式选择具有重要的指导意义.

Soil microorganisms are essential components of forest ecosystems that respond quickly to external disturbances.Thus,they have been used as ideal indicators to evaluate the influence of anthropogenic activities on soil properties and their associated functions.Here,the effects of different tending measures on soil microbial abundance,community structure using high-throughput sequencing,and their rapid response mechanisms in Picea asperata plantations were investigated one year after the tending measures.The experimental treatments consisted of two thinning intensities(T_(1) and T_(2))and two pruning intensities(P_(1) and P_(2)),with no thinning or pruning as a control(T_(0) or P_(0)).The diversity index of the soil microbial community was not affected by the interaction between thinning and pruning,except for fungal richness.The richness,diversity,and evenness index of the soil bacterial communities decreased significantly with thinning,whereas those of the soil fungi community did not.Compared with the control treatment,the diversity of soil bacterial communities at 1-m pruning height increased significantly.Thinning and pruning showed significant interaction effects on the phyla Gemmatimonadetes and Planctomycetes,whereas the relative abundance of each dominant bacterial group was not significantly different among the different thinning and pruning intensities.The effect of thinning measures on the relative abundance of dominant fungal groups was more significant,with Ascomycota and Basidiomycota increasing significantly after thinning.Redundancy analysis showed that soil capillary porosity and available potassium and phosphorus were the main factors affecting soil bacterial community richness.Available potassium was the main factor affecting fungal richness.Both Planctomycetes and Gemmatimonadetes are more easily affected by environmental changes in the soil.Thinning and pruning were found to affect the diversity of soil microbial communities and increase the abundance of dominant soil fungal groups.The findings provide important guidance for the healthy management and model selection for spruce plantations.