Land use changes: a key ecological driver regulating methanotrophs abundance in upland soils

Land use changes have been recognized as one of the key ecological drivers in regulation of methane (CH 4 ) consumption from dry upland soils. This study investigated the impact of land use changes and different soil depths (0–10, 10–20 and 20–30 cm) on soil physicochemical properties and methanotrophs abundance in dry tropical region of Vindhyan uplands. Four different land use types (agriculture land, mixed forest, savanna and natural forest) were selected for a comparative study. Among the different land uses and soil depths, results indicated significantly higher soil moisture (SM), organic-C, inorganic nutrients, water holding capacity (WHC) and methanotrophs abundance at 0–10 cm depth of natural forest compared to other sites. Across different land uses, number (8.11 × 10 7 pmoA copies g −1 of dry soil) of methanotrophs isolated from the natural forest soil was statistically higher than the soils of other land use types. The variations in pmoA gene numbers across different land uses and soil depths were significant ( P < 0.001). The pmoA gene numbers were positively correlated with soil C/N ratio ( R 2 = 0.9233) and moisture ( R 2 = 0.9675) contents. The decreasing order of pmoA gene abundance across different land uses was natural forest > mixed forest > savanna > agriculture land. The result suggest that land use changes (conversion of natural forest to agricultural land) alter the major soil properties (SM, WHC, organic matter, C/N ratio, etc.) and significantly reduce the methanotrophs and pmoA gene numbers. The land use management practices (application of bio-fertilizers in place of chemical fertilizers), especially for the degraded agricultural soils, could be beneficial option to mitigate the negative impacts on soil methanotrophs and their CH 4 sink activity in the upland soil of Vindhyan region.