Land use change alters phosphatase enzyme activity and phosphatase-harboring microbial abundance in the subalpine ecosystem of southeastern Qinghai-Tibet Plateau, China

In the presence of limited phosphorus (P) in terrestrial ecosystems, exploring how land use change (LUC) affects phosphatase enzyme activity and microbial communities is important for managing soil P, because microorganisms carry out the majority of P cycling in the soil through producing phosphatase enzymes. In this study, we explored the impact of LUC on P availability, phosphatase enzyme, the abundance of phosphatase-encoding genes, and microorganisms. We collected 168 soil samples at soil depths of 0-20 cm and 20-40 cm from seven sampling sites, each of which represented by four different land uses: artificial forests (AF), farmlands (FL), natural forests (NF), and shrubland (SL). We analyzed phosphatase-encoding genes and microbes from metagenome datasets. Results indicated that P availability substantially increased following NF to FL conversion. In contrast, phosphatase enzyme activity significantly decreases when NF is converted to different land uses, due to the decline of soil organic carbon (SOC), moisture content (MC) and total nitrogen (TN). We have also detected 13 P solubilizing and mineralizing genes. The phoD and gcd were the dominant mineralizing and solubilizing genes, respectively. Farmland had higher gcd gene abundance, while NF had significantly higher phoD gene abundance. The gcd gene abundance were mainly governed by pH and total P, whereas pH and available P were the primary factors controlling phoD gene. MC, SOC and TN regulated other genes detected in this study. With regard to the dominant gcd-harboring phyla, Acidobacteria, Proteobacteria, Bacteroidetes and Gemmatimonadetes were the dominant, while Proteobacteria, Acidobacteria, Actinobacteria, and Candidatus_Rokubacteria were the dominant phoD-harboring phyla. The majority of gcd and phoD-harboring microorganisms were primarily controlled by pH, available P and total P. However, some phyla also regulated by MC, SOC, and TN. In general, our findings suggested that LUC significantly alters phosphatase enzymes and the abundance of phosphate-encoding genes and microbes. These changes have significant implications for soil P cycling.