Effects of yak dung deposition on soil enzyme activities in an alpine meadow in the Tibetan Plateau

Yak dung deposition is one of the important ways to maintain the function of grassland ecosystems in the Tibetan Plateau. The effects of yak dung deposition on soil physicochemical properties are well established; however, little is known regarding the effects of yak dung deposition on soil enzyme activities. the present study investigated the effects of yak dung deposition on soil enzyme activities and its potential regulatory factors in a Tibetan alpine meadow. Dung deposition significantly increased soil microbial biomass carbon (MBC) (P < 0.001) and nitrogen (MBN) (P < 0.001) content by 14.24% and 20.29%, respectively. Dung depositionn significantly increased the enzyme activity of β-1, 4-glucosidase (BG) (P < 0.001), β-1, 4-xylosidase (BX) (P < 0.001) and urease (URE) (P < 0.001) by 8.4%, 8.2% , and 6.6%, respectively. Further, dung deposition significantly increased soil moisture content (SMC) (P < 0.01) dissolved organic carbon (DOC) (P < 0.001), and dissolved organic nitrogen (DON) (P < 0.001), but decreased soil pH (P < 0.001). Redundancy analysis revealed that soil enzyme activities were significantly and positively associated with DOC (P < 0.001), DON (P < 0.001), MBC (P < 0.001) and MBN (P < 0.001) but significantly and negatively associated with soil pH (P < 0.05). Moreover, dung-induced variations in available substrates (DOC and DON) were more important in regulating soil enzyme activities than those in microbial biomass (MBC and MBN). These results indicate that yak dung deposition can improve soil microbial activity through providing liable carbon and available nutrients, and it can be play an important role in regulating soil carbon and nutrient cycling in a grazed alpine grassland ecosystem in The Tibetan Plateau.