Influence of forest types on soil physicochemical and biological characteristics of associated agroecosystems in the central Himalaya.

Forests significantly influence the dynamics of microbial biomass and soil nutrients in neighboring agricultural lands. Little information is available on how forest types affect the physicochemical and microbial dynamics of soil in surrounding agroecosystems. The present study evaluated the influence of forest types on soil physicochemical and biological characteristics of forest and associated agricultural systems in the Himalaya. The study was conducted in three forests Banj-oak (OF), Chir-pine (PF), and Nepalese-alder (AF)) and adjacent agricultural lands (OA, oak-adjacent), (PA, pine-adjacent), and (AA, alder-adjacent). Soil samples were collected from three depths (0-10, 10-20, and 20-30 cm). Using two-way ANOVA, soil variables were tested for their effects, including interactions among land-use types and depths. PCA was used to investigate the relationship between land-use types, soil depths, and soil physicochemical and biological characteristics. ANOVA results showed that soil porosity (P), organic carbon (C), total nitrogen (N), bioavailable phosphorous (P), microbial biomass carbon (C), and nitrogen (N) significantly varied (p < 0.05) across land-use types, soil depths, and land-use types × soil depths (p < 0.001) and followed: AF > AA> OF>OA > PF > PA. The soil moisture (M), C, N, P, C, and N declined with soil depths: 0-10 > 10-20 > 20-30, although variations between lower-surface depths (10-20 and 20-30 cm) were not significant. PCA analysis showed that soil C, P, and pH were the primary regulators of microbial biomass across land-use types and soil depths. Compared to PF, AF and OF have a greater positive influence on soil nutrients and microbial biomass of adjacent agroecosystems. In conclusion, forest vegetation type influences soil microbial biomass by buffering soil substrate (e.g., C, N, pH) in forest and adjacent agricultural lands. The findings may help in developing strategies for sustainable agriculture adjacent to forest ecosystems, by maintaining long-term soil quality in the central Himalaya.