Responses of Soil Microbial Community Structure and Potential Mineralization Processes to Solidago canadensis Invasion

Solidago canadensis is a noxious invasive weed of Eastern China. It is still unclear how its invasion affects the soil microbial community structure and mineralization processes. Therefore, the microbial community structure (assessed by phospholipid fatty acid [PLFA]) and potential mineralization processes associated with its invasion were measured in five field areas in Zhejiang Province, China. Phospholipid fatty acid abundances of bacterial, fungal, actinomycete, two function groups (i.e., Gram-negative bacteria and mycorrhizae), and two ratios for Gram-negative/positive bacterial PLFAs and fungal/bacterial PLFAs were significantly higher in soils invaded by Solidago than in the native soil (P < 0.05), whereas the ratio cy17:0/16:1ω7 decreased (P < 0.05). Ammonification, cellulose, and organic phosphorus mineralization also significantly increased following the invasion of Solidago, respectively, but the nitrification significantly decreased (P < 0.05). Principal components analysis for the PLFA data sets clearly discriminated the native plots from the invaded plots. Redundancy analysis with Monte Carlo permutation tests showed that some PLFAs such as 10:0, 12:0, cy17:0, cy19:0, 16:1ω7, 18:1ω9, 18:1ω7, 18:2ω6, 16:1ω5, 10Me18:0, 10ME17:0, 10Me16:0, 17:1ω8, and 18:0 were strongly correlated with rates of ammonification, nitrification, and cellulose and organic phosphorus decomposition. These results suggest that the invasion-induced changes in soil microbial community structure and nutrient transformation processes (especially nitrification inhibition and ammonification promotion) may be one of the reasons why Solidago becomes predominant in competition with indigenous species for soil nutrients in the invaded ecosystem.