Variation in soil microbial communities across a boreal spruce forest landscape

We investigated soil microbial community structure by phospholipid fatty acid (PLFA) analysis in a mature boreal Spruce forest landscape in southern Norway. with low diversity of vascular plants. We investigated the spatial variation ill PLFAs and the importance of environmental variables in 10 plots (each 13 samples) in a study area of 1 km x 1 km. The scales investigated were 15 cm to 10 m within study plots and 100 m to 1 km between study plots. Soil microbial biomass varied 10-fold and we found a large variation in microbial community structure, even at distances of 15 cm. Samples aggregated into plots when PLFAs were subjected to a principal components analysis. Plot identity explained 36.3% of the variation in the PLFAs and geostatistical analysis showed that the microbial community structure displayed spatial dependence at within-plot distances. Environmental variables differed significantly between all plots but explained only minor parts of the variation in the overall PLFA pattern. The vegetation variables were, however, the best at explaining the PLFA pattern, and up to 60% of within-plot variation in individual plots, respectively, Could be explained by vegetation variables, pH, and soil depth.