Relationship between Mikania micrantha invasion and soil microbial biomass, respiration and functional diversity

Abstract

The relationship between Mikania micrantha invasion and soil microbial communities was studied across the invasive gradients varying from 0 to 38, 80, and 100% coverage of M. micrantha. The results showed microbial biomass C, N, and P all increased as the cover of M. micrantha increased. Soil microbial quotient Cmic/Corg (microbial biomass C/organic C) tended to increase linearly with the cover of M. micrantha. Basal respiration (BR) also showed a similar trend. The respiratory quotient qCO2 decreased with M. micrantha invasion, and remained at quite a constantly low level in the invasive soils. Community level physiological profiles (CLPP) analyses indicated that M. micrantha invasion tended to result in higher average well color development, substrate richness, and functional diversity. Average utilization of specific substrate guilds was highest in M. micrantha monoculture. Principle component analysis of CLPP further indicated that M. micrantha monoculture was distinctly separated from the native area and the ecotones. In conclusion, M. Mikania invasion improved soil microbial biomass, respiration and utilization of carbon sources, and decreased qCO2, thus created better soil conditions, which in turn were more conducive to the growth of M. micrantha.