Soil microbial community characteristics in degraded karst tiankeng invaded by Eupatorium adenophorum.

Abstract

After invading the grand negative landform karst degraded tiankeng, Eupatorium adenophorum will affect the plant diversity, community succession and natural ecological restoration of degraded tiankeng by changing soil microbial community. Taking the degraded tiankeng "Bajiaxiantang" as the research area, the soil around E. adenophorum roots in different habitats was selected to explore the microbial community characteristics of E. adenophorum roots using the Biolog-ECO micro-plate method. The results showed that the invasion degree of E. adenophorum was in order of pit slope shrub-grassland > pit bottom grassland > pit slope forest > pit head shrub-grassland. The characteristics of E. adenophorum varied among different habitats due to habitat heterogeneity. The change of microbial community metabolic activity, dominance index, richness index and evenness index of E. adenophorum roots was closely related with the invasion degree, with significant diffe-rence between inside and outside of the tiankeng. Amino acids and polymers were the main carbon sources utilized by soil microorganism. The α diversity of herbaceous plants in different habitats were correlated with that of soil microbial community. The diversity of soil microbial community around E. adenophorum roots increased significantly with the increases of invasion level, which could form a microenvironment conducive to invasion and colonization. In the future, the degraded tiankeng would eventually form the climax community of underground forests with community succession and natural ecological restoration, which might result in the disappearance of E. adenophorum in the degraded tiankeng.