森林土壤C:N:P生态化学计量垂直格局及理化驱动OA

[Objective]This study aimed to reveal the vertical variation patterns of soil carbon(C),nitrogen(N),phosphorus(P)contents and their ecological stoichiometric characteristics in three typical forest types(Juniperus tibetica forest,Picea balfouriana forest,and Quercus aquifolioides forest)in Qamdo,eastern Xizang,clarify the driving mechanisms of soil physicochemical properties on their spatial variability,and provide scientific support for analyzing nutrient cycling processes and sustainable management of high-altitude forest ecosystems in eastern Xizang.[Method]Collect soil samples from the 0-20 cm,20-40 cm,and 40-60 cm soil layers in three forest types.Soil physicochemical properties and C,N,P contents were determined,and redundancy analysis(RDA)and principal component analysis(PCA)were combined to explore the driving mechanisms.[Result]The results showed that:(1)There were significant forest type differences and vertical variations in soil physicochemical properties among the three forest types.Picea balfouriana forest exhibited the characteristics of"low bulk density,high water content,and high porosity";Quercus aquifolioides forest had the lowest pH value and clay content but the highest sand content;bulk density was significantly lower in the topsoil than in the middle and deep layers,and pH value showed a deep-layer acidification trend.(2)C and N contents showed a consistent vertical decreasing pattern with surface enrichment;C and N contents in Juniperus tibetica forest and Picea balfouriana forest were significantly higher than those in Quercus aquifolioides forest;the vertical variation of P content was gentle;the vertical variation of C/P ratio was the most consistent(all significantly decreasing).The topsoil of Picea balfouriana forest showed P limitation,while Picea balfouriana forest and Juniperus tibetica forest showed N limitation overall,and Quercus aquifolioides forest had no obvious nutrient limitation.(3)The driving effects of physicochemical properties on stoichiometric characteristics were forest type-specific and depth-dependent:Juniperus tibetica forest was affected by sand content,pH value,and porosity;Picea balfouriana forest was dominated by bulk density and water content;Quercus aquifolioides forest was regulated by clay content and porosity;the correlation between topsoil physicochemical properties and stoichiometric characteristics was more direct.[Conclusion]Soil pH value,sand content,bulk density,porosity,water content,and organic matter can be selected as key monitoring indicators for the vertical variation of soil ecological stoichiometric characteristics in Qamdo during forest soil environmental monitoring,and provide references for subsequent soil improvement.