Effects of thinning and litter manipulation on soil phosphorus dynamicsin a Larixprincipis-rupprechtii plantation

Soil phosphorus（P） plays an important role in maintaining the stability of ecosystem functions. Understanding the effects of forest management practices（e.g., thinning） on soil phosphorus fractions is important for soil phosphorus management for sustainable development in forest ecosystems. In this paper, a modified Hedley phosphorus fractionation method was used to sequentially extract soil samples and investigate the characteristics of soil phosphorus fractions with different thinning intensities(control, T0; Low thinning, T15; Moderate thinning,T35; Heavy thinning,T50)and litter manipulation（control, CK; exclusion litter, NL; addition litter, DL; exclusion litter and roots, NRL） in a Larixprincipis-rupprechtii plantation and addressed its determining factors. The results showed that soil labile phosphorus（Resin-Pi, NaHCO3-Pi and NaHCO3-Po）, soil microbial biomass phosphorus, and acid phosphatase activity increased first and then decreased with the increase of thinning intensity, and the maximum appeared in T35.DL treatment significantly increased soil labile phosphorus（Resin-Pi, NaHCO3-Pi and NaHCO3-Po）, soil microbial biomass phosphorus, and acid phosphatase activity. No-labile phosphorus（HCl-Pi, concentrated HCl-Pi and concentrated HCl-Po） and residual phosphorus（Residual-P） were not affected by thinning or litter treatments. The redundancy analysis（RDA） indicated that the changes in phosphorus fractions were mainly driven by soil microbial biomass phosphorus, acid phosphatase activity, andsoil organic carbon in the surface soil of the Larixprincipis-rupprechtii plantation. The results suggested that moderate thinning and increased litter could significantly improve the activation of phosphorus in the surface soil of the Larixprincipis-rupprechtii plantation.