Geographical structure of soil microbial communities in northern Japan: effects of distance, land use type and soil properties.

摘要

Geographical assemblages of biological community are explained by natural selection and/or by stochastic processes of death and recruitment of individuals. We evaluated geographical pattern of the structure of soil bacterial and fungal communities at 32 sites distributed over 8000 km2 in northern Japan, to examine (1) relative contribution of environmental factors and geographical distance (2) roles of land use types and soil properties, and (3) differences in spatial pattern between bacterial and fungal communities. The abundance and composition of soil bacterial and fungal communities were evaluated by phospholipid fatty acid (PLFA) profiling and denaturing gradient gel electrophoresis (DGGE) method with 16S rDNA and 18S rDNA. PLFA profiling and DNA fingerprinting revealed that geographical distance did not significantly affect geographical patterns of microbial communities, while land use and soil chemical properties had large significant effects. The four land use types (bare ground, agricultural land, grassland, and forest) explained about 30.0% of the total variation in bacterial PLFA abundance, mostly because of their differing soil properties. Correlations with soil properties suggest that litter input from aboveground vegetation determines the bacterial abundance in bare ground and agricultural land, whereas soil pH regulates the bacterial abundance in grassland and forests. DGGE results suggest that fungal community structure is sensitive to human disturbance because agricultural land showed significantly different fungal community structure from other types.