Spatial heterogeneity of microbial community and enzyme activities in a broad-leaved Korean pine mixed forest

Soil microbial communities support a great belowground biodiversity, but our knowledge regarding their spatial patterns and underlying driving mechanisms in small scale is very limited, especially for forest ecosystems. The spatial distributions of microbial community and enzyme activities depending on soil environmental factors were studied using geostatistical tools. 55 soil samples were collected across a 30 m × 40 m plot in a broad-leaved Korean pine mixed forest in the Changbai Mountains. Abundances of total and bacterial PLFAs had stronger spatial dependence than fungal PLFAs. Gram-positive bacteria had stronger spatial dependence than Gram-negative bacteria, suggesting that Gram-negative bacteria are more susceptible to stochastic factors. The proportions of structural variance for the activities of β-1,4-glucosidase (βG), β-1,4-N-acetylglucosaminidase (NAG) and acid phosphatase (AP) were 0.997, 0.519 and 0.966, respectively, suggesting that βG and AP had high spatial dependence. Cross-variogram analysis showed that root biomass played a critical role in structuring the spatial distributions of total and bacterial PLFAs. Fungi had close spatial connection with total nitrogen (TN), particulate organic carbon and root biomass within the ranges of 8.2-13 m. The βG, NAG and AP activities were closely spatially connected to the soil organic carbon and TN and were all spatially correlated with fungal abundance. Overall, microbial community and enzyme activities were patchily distributed at small spatial scales. Close spatial connections between microbial communities, enzyme activities, and root biomass and soil variables help to understand the main drivers of belowground soil biodiversity in the forest.