云南乌蒙山国家级自然保护区珙桐林生态化学计量特征

Ecological stoichiometry characterization of Davidia involucrata in Wumeng Mountion National Nature Reserve of Yunnan Province

【目的】探究国家Ⅰ级珍稀濒危植物珙桐生态化学计量特征,揭示珙桐林生态系统养分元素状况和生长限制因子。【方法】在云南乌蒙山国家级自然保护区不同海拔段设置4个样地,编号分别为Ⅰ、Ⅱ、Ⅲ、Ⅳ,利用单因素方差分析及多重比较等方法研究珙桐林叶片-凋落物-土壤3种组分C、N、P含量及其比值的差异性、相关性,用冗余分析方法探究土壤化学计量特征的响应因子。【结果】珙桐叶片C、N、P平均含量分别为520.97、22.73、1.43 g/kg,凋落物C、N、P平均含量分别为459.87、10.96、1.35 g/kg,土壤C、N、P平均含量分别为74.81、7.94、0.79 g/kg,叶片、凋落物、土壤C、N、P平均含量表现为叶片>凋落物>土壤。不同样地同一组分间土壤C、N、P含量差异显著,表现为Ⅳ>Ⅲ>Ⅱ>Ⅰ(Ⅰ:58.47±1.88、5.73±0.41、0.06±0.02 g/kg;Ⅱ:64.45±2.29、6.82±0.19、0.61±0.08 g/kg;Ⅲ:75.94±1.32、7.88±0.16、1.11±0.06 g/kg;Ⅳ:100.39±1.24、11.32±0.25、1.36±0.10 g/kg),叶片、凋落物差异不显著;同一样地不同组分间C含量差异显著,表现为叶片>凋落物>土壤,N、P含量差异不显著;不同样地同一组分、同一样地不同组分间C∶N、C∶P、N∶P存在显著差异。叶片、凋落物、土壤C、N、P含量及比值间相关性显著;海拔、非毛管孔隙度和坡度、毛管孔隙度、粉砂粒含量是影响土壤养分含量的关键环境因子。【结论】云南乌蒙山国家级自然保护区珙桐林不同海拔样地间土壤C、N、P含量及其比值存在显著差异,叶片、凋落物差异不明显,根据生态化学计量特征表明样地Ⅳ珙桐生长受P元素限制,海拔、非毛管孔隙度、坡度、毛管孔隙度、粉砂粒含量是影响珙桐林土壤养分循环的关键环境因子。

【Objective】This study aimed to investigate the ecological stoichiometry characterization of Davidia involucrata,a nationally protected endangered plant species,in the Wumeng National Nature Reserve of Yunnan Province.The objective was to assess the nutrient element content and growth-limiting factors in Davidia involucrata ecosystems by examining the leaf,litter,and soil.【Method】Four sample plots were established at different elevations(labeled as I,II,III,IV)in the study area.Variance analysis,multiple comparisons,and redundancy analysis were used to study the differences and correlations in carbon(C),nitrogen(N),phosphorus(P)content,and their ratios in Davidia involucrata leaves,litter,and soil.The response factors of soil stoichiometric characteristics were explored.【Result】The average leaf content of C,N,and P was 459.87,10.96,and 1.35 g/kg respectively,while the average litter content was 459.87,10.96,and 1.35 g/kg respectively.The average soil content was 74.81,7.94,and 0.79 g/kg respectively.The pattern of C,N,and P content in leaf,litter,and soil followed the order:leaf>litter>soil.Significant differences in soil C,N,and P content were observed among the different components.The order of content was IV>III>II>I(I:58.47±1.88,5.73±0.41,0.06±0.02 g/kg;II:64.45±2.29,6.82±0.19,0.61±0.08 g/kg;III:75.94±1.32,7.88±0.16,1.11±0.06 g/kg;IV:100.39±1.24,11.32±0.25,1.36±0.10 g/kg).Leaf and litter did not show significant differences.Significant differences were observed in C content among the components within each plot,with the order of leaf>litter>soil.N and P content did not show significant differences.The C∶N,C∶P,and N∶P ratios exhibited significant differences.Correlations were found between C,N,P content,and their ratios in leaf,litter,and soil.Altitude,non-capillary porosity,slope,capillary porosity,and silty sand content were identified as key environmental factors influencing soil nutrients.【Conclusion】Significant differences were observed in soil C,N,P content,and their ratios across different elevation sites in the Wumeng National Nature Reserve of Yunnan Province.However,leaf and litter did not show significant differences.Based on ecological stoichiometry characterization,it can be concluded that the growth of Davidia involucrata in plot IV is more likely to be restricted by the P element.Altitude,non-capillary porosity,slope,capillary porosity,and silty sand content were identified as key environmental factors affecting soil nutrient cycling.