Effects of the invader Solidago canadensis on soil properties

Abstract

A perennial goldenrod weed, Solidago canadensis, is rapidly spreading in China and now poses a serious threat to native ecosystem structure and function. Little is known about the effects of S. canadensis invasion on rhizosphere physico-chemical properties and microbial communities. The objective of this study was to compare the soil physico-chemical properties and microbial communities of invaded (two ecotone sites and one monoculture site) and native plant rhizospheres in field areas of Zhejiang Province, Eastern China. Compared with those in the native site, soil total nitrogen, total phosphorus, NO 3-N, available phosphorus content, and aggregate stability consistently decreased with S. canadensis invasion, while soil organic carbon, NH 4-N content, pH, and bulk density in the invaded sites significantly increased. Soil microbial biomass (expressed by carbon, nitrogen, or phosphorus content), activity (basal respiration and substrate induced respiration), and functional diversity (calculated from the average well color development (AWCD) of 31 carbon sources in a BIOLOG Ecoplate) significantly increased with S. canadensis invasion. Microbial utilization of carbohydrate groups significantly increased in the invaded sites, while the utilization of carboxylic acids and amines/amides groups significantly decreased. Principal components analysis (PCA) of the AWCD data indicated that the heavily invaded site (monoculture) was clearly separated from the native site. Redundancy analysis (RDA) indicated that soil organic carbon, NH 4-N, NO 3-N, and pH significantly impacted the dynamics of microbial parameters across the invaded sites. These results suggested that several soil chemical properties (e.g., organic carbon, NH 4-N, and pH) and microbial parameters (e.g., microbial biomass, basal respiration, substrate induced respiration, and functional diversity) might be used as indicators of S. canadensis invasion density.