土壤微生物群落对麻栎-刺槐混交林凋落物分解的影响

Abstract

以麻栎-刺槐混交林和麻栎纯林为研究对象，采用野外定点采样、室内分析与高通量测序的方法，对凋落物分解过程中土壤微生物菌群多样性特征及其对凋落物分解速率的影响进行了研究。结果表明：（1）麻栎-刺槐混交林凋落物的分解速率高于麻栎纯林。两种林分凋落物有机碳（TOC）、全氮（TN）发生释放，全磷（TP）发生积累-释放的过程。（2）两种林分土壤细菌优势类群为放线菌门（Acidobacteria）、变形菌门（Proteobacteria）、酸杆菌门（Actinobacteria）和疣微菌门（Verrucomicrobia），土壤真菌优势类群为担子菌门（Basidiomycota）、子囊菌门（Ascomycota）和被孢霉门（Moritierellomycota）。（3）凋落物分解过程中，麻栎-刺槐混交林土壤微生物菌群丰富度指数和菌群多样性指数变化范围小于麻栎纯林。（4）凋落物分解速率与土壤细菌菌群丰富度指数和菌群多样性指数呈显著正相关，与土壤真菌菌群丰富度指数呈显著正相关。土壤微生物群落对麻栎-刺槐混交林和麻栎纯林凋落物分解速率具有重要影响，研究结果为深入开展混交林土壤微生物多样性对凋落物分解的影响研究提供理论依据。;Forest ecosystems are an important part of the terrestrial ecosystem. In forest ecosystems, the plants transmit carbon, nitrogen, phosphorus and other nutrients to the soil in the form of litter. Soil microorganisms, as the main decomposers of litter, affect the energy flow and material circulation of forest ecosystems. This paper took the mixed Quercus acutissima Carruth. and Robiniapseudoacacia L. forest (QR), as well as pure Quercus acutissima Carruth forest (QAC) as research objects. The field fixed-point sampling, indoor analysis, and high-throughput sequencing methods were used to study the characteristics of soil microbial diversity and their effects on the litter decomposition rate. The results were as follows: (1) The litter decomposition rate of QR was higher than that of QAC, the litter decomposition rate of QR was 0.70, and the litter decomposition rate of QAC was 0.62. During the litter decomposition of the two forest stands (QR and QAC), total organic carbon (TOC) and total nitrogen (TN) were released, but total phosphorus (TP) was accumulated first and then released. (2) The two forest stands had the same dominant soil microbial communities, the dominant soil bacterial communities were Actiobacteria, Proteobacteria, Actinobacteria and Verrucomicrobia, and the dominant soil fungi communities were Basidiomycota, Ascomycota and Mortierierellomycota. (3) During the litter decomposition of the two forest stands, the variation range of the soil microbial community richness index and diversity index of QR was smaller than that of QAC. The bacterial community richness index (Chao1 index and ACE index) and community diversity index (Shannon index and Simpson index) of QR and QAC showed a trend of first increasing and then decreasing. The fungal community richness index of QR showed a trend of first decreasing and then increasing, and the fungal community diversity index showed a gradually decreasing trend. The fungal community richness index of QAC showed a gradually decreasing trend, and the fungal community diversity index showed a trend of first decreasing and then increasing. (4) The litter decomposition rate was significantly positively correlated with the soil bacterial community richness index and diversity index, while significantly positively correlated with the soil fungal community richness index. The soil microbial community had an important influence on the litter decomposition rate of QR and QAC. The research results are helpful to understand the relationship between the litter decomposition rate and soil microbial communities in mixed forests, and provide theoretical basis for the research of the influence of soil microbial diversity on litter decomposition in mixed forests.