Soil Microbial Community Composition in a Restored Calcareous Subtropical Wetland

Extreme restoration mechanisms can have important implications in ecosystem development. Complete soil removal during restoration of a freshwater wetland permitted the study of microbial and biogeochemical changes occurring during early development of soils in restored sites of different ages (2-, 5-, 8-,16-yr old). We examined whether the soil microbial community composition (using phospholipid fatty acid analysis, PLFA) was related to the biogeochemical factors across the restored and the undisturbed native site. We observed (i) with accretion of organic matter there was a general shift from N limitation in younger sites to P limitation in the older sites, (ii) soil microbial communities in restored sites were different from that in the native vegetation site, (iii) seasonal variation (dry vs. wet) in microbial community composition in younger restored sites was greater than relatively older sites. Restored sites were characterized by higher relative abundance of fungal biomarkers and higher ratios of gram negative to gram positive compared to the undisturbed native site. Biomarkers for actinomycetes were positively correlated with P concentrations in soils. There did not appear to be any association between fungal biomarkers and soil P. Our results indicate that extreme restoration processes may influence the ecosystem development processes by affecting the soil microbial community composition.