Heavily grazing weakened linkage between phoD community and organic P in typical and desert steppes in Inner Mongolia

Organic P (Po) is dominant P fraction in grassland soils, which plays a decisively role in maintaining P fertility. The transformation of Po was mainly mediated by phoD-harboring bacteria through excreting alkaline phosphatase (ALP). However, how organic P fractions and the phoD community respond to different grazing intensities have not been clearly clarified. Herein, an investigation was conducted in two contrasting steppes in Inner Mongolia, four sheep grazing intensities were established: non-grazing (UG), lightly grazing (LG), moderately grazing (MG), and heavily grazing (HG). Soil Po fractions, ALP activity, the diversity, composition, and abundance of phoD community were analyzed.