土地利用变化后不同种植年限香榧土壤微生物群落的组成及多样性

Microbial Composition and Diversity in Soil of Torreya grandis cv. Merrillii Relative to Different Cultivation Years After Land Use Conversion

为探究毛竹林改种香榧后以及香榧种植年限的增加对土壤微生物群落结构特征的影响,并研究其与土壤肥力因子的关系,运用高通量测序技术,研究毛竹林、香榧5a、香榧+山稻5a、香榧10a和香榧30a土地利用方式下土壤微生物群落组成及多样性的变化.结果表明土地利用改变后,土壤中细菌群落的Shannon指数和Chao l指数显著增加,Simpson指数在香榧30a处显著增加,而Shannon指数在香榧30a土壤中显著降低;真菌群落的Simpson指数和Chao1指数在不同土地利用方式下均无显著变化,Shannon指数在香榧30a土壤中显著降低.土壤微生物群落在属水平上的PCoA分析显示,土地利用方式对细菌和真菌群落结构变化有显著影响,其中香榧5a和香榧+山稻5a的菌群结构最为相似.土壤细菌优势菌门主要包括酸杆菌门、变形菌门、放线菌门和绿弯菌门,土地利用方式改变后,土壤细菌属的组成也发生了显著改变,多数优势细菌群落随着种植年限增加丰度减少;土壤真菌的优势菌门主要包括子囊菌门、担子菌门和接合菌门,其群落变化特征与细菌类似.RDA分析结果显示,土壤肥力指标包括:pH、有机质、速效磷、速效钾和水溶性有机碳氮与土壤微生物群落显著相关,是影响土壤微生物优势群落的主要驱动因子.

In order to explore the impacts of the land use conversion from a Phyllostachy pubescens(moso bamboo) forest to a Torreya grandis cv. Merrillii plantation, as well as the cultivating years of the T. grandis cv. Merrillii plantation, on the soil microbial community, this research studied the soil microbial structure and diversity of a moso bamboo forest, T. grandis cv. Merrillii plantations(5, 10, and 30 a), and a T. grandis cv. Merrillii-mountain rice interplanting plantation(5 a) using the high-throughput sequencing technique, and the relationship between the microbial community and environmental factors was further explored. The results showed that after the land use change, the Shannon index and Chao1 index of the soil bacterial community increased significantly;the Simpson index increased significantly in the 30 a T. grandis cv. Merrillii plantation, whereas the Shannon index decreased significantly. Both the Simpson index and Chao index of the soil fungal community had no significant difference under different land use types. whereas the Shannon index was significantly decreased in the 30 a T. grandis cv. Merrillii plantation. PCoA analysis of the soil microbial community at the genus level showed that land use type played a vital role in driving the changes in soil bacterial and fungal communities. The compositions of the soil microbial communities between the two 5 a stands were most similar. The dominant phyla of soil bacteria mainly included Acidobacteria, Proteobacteria, Actinobacteria, and Chloroflexi. The results of cluster analysis showed that the soil bacterial community changed significantly at the genus level after the conversion of land use;the abundance of most dominant bacterial communities decreased with increasing cultivation. The fungal community was mainly composed of Ascomycota, Basidiomycota, and Zygomycota, whose changes in community characteristics were similar to those of bacteria. The results of RDA analysis showed that pH, organic matter, available phosphorus, available potassium, and water-soluble organic carbon and nitrogen were significantly correlated with soil microbial community. Therefore, these soil fertility properties might be the driving factors affecting the structure of bacterial communities. This study provided a theoretical basis for solving the problem of soil quality deterioration in T. grandis cv. Merrillii stand land management.