马尾松人工林土壤碳氮磷生态化学计量学特征的纬度变化

Latitudinal Variations of Soil C-N-P Stoichiometry in Pinus massoniana(Lamb.)Plantations

[目的]探讨马尾松人工林土壤碳、氮、磷养分及其生态化学计量学特征的纬度变化,为马尾松人工林的可持续经营和生产力提高提供科学依据。[方法]通过对亚热带地区东南至西北8个研究点马尾松人工林0~20 cm矿质土层土壤有机碳、全氮、全磷含量的测定,利用回归分析法探索土壤碳、氮、磷含量及其生态化学计量学特征的纬度变化趋势,利用Pearson相关法和冗余分析法分析气候因子(年均气温和年均降水量)、林分特征(年龄、密度和胸径)和土壤性质(pH值与黏粒含量)对其纬度变化的影响,采用方差分解法分析气候、林分和土壤因子对其纬度变化的相对贡献率。[结果](1)土壤有机碳、全氮、全磷的平均含量分别为16.02、1.22、0.35 g·kg^(-1),土壤碳氮比、碳磷比、氮磷比的平均值分别为14.18、47.01、3.59;(2)土壤有机碳和全氮含量均随纬度的升高而显著降低(P<0.01),全磷含量无明显的纬度变化;(3)土壤碳氮比随纬度的升高而显著增大(P<0.05),碳磷比和氮磷比却显著下降(P<0.01);(4)土壤有机碳和全氮含量与年均气温、年均降水量、胸径呈显著正相关(P<0.05),与土壤pH值呈显著负相关(P<0.05);土壤碳磷比和氮磷比与年均气温、年均降水量、胸径、土壤黏粒含量呈显著正相关(P<0.05),与林分年龄呈显著负相关(P<0.05);(5)气候因子、林分特征和土壤性质总体上解释了63.8%土壤有机碳、全氮和全磷含量及其生态化学计量学特征的变化,相对贡献率表现为气候因子(46.3%)>林分特征(43.3%)>土壤性质(35.5%)。[结论]在马尾松人工林中,土壤碳氮比、碳磷比和氮磷比表现出明显的纬度变化,年均气温、年均降水量、林分年龄、林分密度、胸径、土壤pH值、土壤黏粒含量是其驱动因素,这些因素的交互效应大于单独效应。

[Objective]To explore the latitudinal variations of soil organic carbon(C),total nitrogen(N)and total phosphorus(P)and their ecological stoichiometry in Pinus massoniana(Lamb.)plantations of subtropical China.[Method]Soil samples of 0-20 cm layer were collected from the pure plantations in eight sites ranging from southeast to northwest to determine the contents of soil organic C,total N and total P.The variations of soil C-N-P contents and their ecological stoichiometry along the latitudinal gradient were explored by regression analysis.The relationships of climatic factors(mean annual temperature,MAT and mean annual precipitation,MAP),stand characteristics(age,density and DBH)and soil key properties(pH value and clay content)with soil C-N-P contents and stoichiometry were examined by Pearson’s correlation analysis and redundancy analysis.Besides,the relative contribution rates of these environmental factors to the variations in soil C-N-P contents and stoichiometry were analyzed using the variation partitioning analysis.[Result]The average contents of soil organic C,total N and total P were 16.02,1.22,and 0.35 g·kg^(-1),respectively;and the average ratios of soil C:N,C:P and N:P were 14.18,47.01,and 3.59,respectively.Both soil organic C and total N decreased significantly(P<0.01)with increasing latitude,while no obvious spatial pattern of total P was found.Soil C:N significantly increased(P<0.05)while soil C:P and N:P decreased(P<0.01)over latitude.The soil organic C and total N were significantly positively correlated with MAT,MAP,and diameter at breast height(DBH)(P<0.05),but negatively correlated with soil pH value(P<0.05).The soil C:P and N:P were significantly positively correlated with MAT,MAP,DBH,and soil clay content(P<0.05),while negatively correlated with stand age(P<0.05).Climatic factors,stand characteristics and soil key properties totally explained 63.8%of latitudinal variations in soil organic C,total N,total P and soil C:N,C:P,N:P,with characteristics of climatic factors(46.3%)>stand characteristics(43.3%)>soil properties(35.5%).[Conclusion]Soil C:N,C:P and N:P in P.massoniana(Lamb.)plantations follows obvious latitudinal patterns,which are driven by MAT,MAP,stand age,stand density,DBH,soil pH value,and soil clay content.Importantly,the interaction effects of these environmental factors are greater than the single effects.