磷养分添加对亚热带两种不同林分森林土壤微生物残体碳的影响OA北大核心

Soil microbial residue carbon(MRC)is an important component of soil organic carbon(SOC),but how phosphorus nutrients affect the content and composition of soil MRC in subtropical forests remains unclear.This study focused on the soils of natural forests of Castanopsis carlesii and plantations of Cunninghamia lanceolata,conducting indoor culture experiments with control(CT,0 g·kg-1)and phosphorus addition(P,0.1 g·kg-1).Changes in soil amino sugar content,chemical properties,and enzyme activity following phosphorus addition were observed to investigate the impact of phosphorus nutrients on soil MRC content and composition in these subtropical forest soils.The results showed that:(1)Phosphorus addition significantly increased the soil pH and dissolved organic carbon(DOC)content in the soils of Castanopsis carlesii natural forest by 3.3%and 23.7%,respectively,while the pH of Cunninghamia lanceolata plantation soils increased significantly by 3.9%.(2)The effects of phosphorus addition on soil MRC content and composition varied with forest type.In the Castanopsis carlesii natural forest,phosphorus addition increased the soil MRC content and its contribution to SOC by 25.7%and 22.4%,respectively,whereas no significant effects were observed in the soils of Cunninghamia lanceolata plantation.(3)Correlation analysis revealed a negative correlation between MRC content and the β-N-acetylglucosaminidase(NAG)activity.Redundancy analysis showed that changes in DOC content explained 74.5%of the variation in soil MRC,suggesting that phosphorus nutrients regulate soil residue carbon accumulation primarily by affecting the formation and decomposition processes of soil MRC.