紫茎泽兰入侵下喀斯特退化天坑的土壤微生物群落特征

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

紫茎泽兰入侵到宏大地表负地形的喀斯特退化天坑后,会通过改变其立地环境的土壤微生物群落来影响退化天坑的植物多样性、群落演替与自然生态恢复.以云南沾益天坑群的典型退化天坑巴家陷塘为研究区,选择不同生境的紫茎泽兰根系土壤,采用Biolog微平板法探究紫茎泽兰根系土壤微生物群落特征.结果表明:受退化天坑内生境异质性影响,紫茎泽兰的入侵程度表现为坑坡灌草地>坑底草地>坑坡林地>坑口灌草地,并且不同生境的紫茎泽兰性状特征存在差异;紫茎泽兰根系土壤微生物代谢活性、优势度指数、丰富度指数、均匀度指数与其入侵程度具有一致的变化趋势,且坑内外差异显著;糖类和氨基酸类为土壤微生物利用的主要碳源;不同生境的草本层植物α多样性与土壤微生物群落多样性存在相关性.紫茎泽兰根系土壤微生物群落多样性会随入侵程度的增加而显著提高,形成有利于入侵定植的微环境.未来退化天坑经过植物群落演替和自然生态恢复,最终形成地下森林顶极群落,可能使紫茎泽兰在退化天坑中消失.

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.Theαdiversity 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.