马尾松人工林林隙大小对土壤理化性质的影响及土壤质量评价OA

[Objective]Investigating the effects of forest gap size on soil quality provides a scientific basis for optimizing soil nutrient management and promoting forest regeneration.[Method]This study examined forest gaps formed by pine wood nematode disturbance in Pinus massoniana plantations in Xingguo County,Jiangxi Province,China.Gaps were classified into five classes(Ⅰ-Ⅴ,small to large)based on diameter-to-height ratio,with adjacent closed-canopy stands as controls.According to the crown width of edge trees,each gap was further divided into a central zone,a transitional zone,and an edge zone.We analyzed physicochemical properties and stoichiometric ratios in surface(0-10 cm)and subsurface(10-20 cm)soils for differences among gap classes and interrelationships,and calculated the soil quality index for comprehensive evaluation.[Result](1)Soil water content in both the surface and sub-surface layers of Class Ⅴ gaps was significantly higher than that in Class Ⅱ,Ⅲ,and Ⅳ gaps(P<0.05).Non-capillary porosity in Class Ⅱ gaps was significantly higher than in Class Ⅰ gaps in the surface layer and significantly higher than in Class Ⅴ gaps in the sub-surface layer(P<0.05).(2)Total phosphorus content in both layers of Class Ⅳ gaps was significantly higher than in Class Ⅴ gaps,and total potassium content in the sub-surface layer of Class Ⅳ gaps was significantly higher than in Class V gaps(P<0.05).Total potassium content in the surface layer of Class Ⅱ～Ⅴ gaps was significantly lower than in the control(P<0.05).(3)In the surface layer,C∶P and N∶P ratios in the edge and transition zones were significantly higher than in the central zone(P<0.05).In ClassⅣ gaps,the sub-surface C∶N ratio and surface N∶P ratio were significantly higher than in the control(P<0.05).(4)As gap size class increased,the overall number of significantly correlated index combinations between soil C,N,and P stoichiometric ratios and soil physical and chemical properties showed a decreasing trend.(5)Soil quality index values in the surface and sub-surface layers of the gaps ranged from 0.37～0.45 and 0.27～0.36,respectively.There were no significant differences in soil quality index among different gap size classes(P>0.05).[Conclusion]Class Ⅳ gaps performed relatively better in improving soil phosphorus and potassium content,and represent a more suitable gap scale for optimizing soil nutrients in P.massoniana plantations in the study area.