The studies of micromycetes fungi and physicochemical properties were carried out on the soils of buffer zones of a small watercourse in the agricultural landscape of north-eastern Poland. One of the zones was under a tree which was adjacent to the arable soil, the other one was under a turf located near the grassland. It turned out that the character of vegetation and the way the land was used had an influence on the analysed soil parameters. Soil under trees was characterized by more diversified structures of fungi communities, it also produced more carbon dioxide and nitrous oxide than soil under turf. This allows us to state that tree-lined buffer zones are more effective in preventing surface water pollution by biogenic compounds displaced from agricultural land compared to the buffer zone under the grassing.