环境因子对秦岭南坡中段松栎混交林物种多样性的影响

Influence of environmental factors on species diversity of pine-oak mixed forest in the middle part of south Qinling Mountains

【目的】研究秦岭南坡中段松栎混交林群落的物种多样性,划分群丛类型,探讨环境因子与不同群丛类型植物多样性的关系。【方法】在陕西省秦岭南坡中段的火地塘和旬阳坝林区,选择松栎混交林群落集中分布地段设置24块样地,对乔木、灌木、草本和环境因子进行调查,并测定土壤理化指标。采用双向聚类分析法(TWINSPAN)划分群丛类型,采用α多样性指数测度不同群丛的物种多样性,对12个环境因子与各群丛的Simpson优势度指数、Shannon-Wiener多样性指数、Patrick丰富度指数和Pielou均匀度指数等进行回归分析。【结果】利用TWINSPAN将研究区24块样地群落划分为8个群丛,其中以油松(Pinus tabulaeformis)+锐齿栎(Quercus aliena var.accuteserra-ta)为主要建群种的群丛是该区分布最广的松栎混交类型。8个群丛之间的物种多样性指数值差异较大,各群丛的Shannon-Wiener多样性指数变化趋势与Patrick丰富度指数变化趋势大体一致,Simpson优势度指数变化趋势与Pielou均匀度指数变化趋势一致。群丛的Patrick丰富度指数与0～20cm土层土壤速效磷含量的指数回归达显著水平(P=0.026 6),与20～40cm和40～60cm土层土壤速效钾含量的二项式回归达显著水平(P=0.026 0,P=0.019 6);Pielou均匀度指数与20～40cm土层土壤速效氮含量的二项式回归达显著水平(P=0.045 9);Shannon-Wiener多样性指数与标准化坡向之间的直线回归达显著水平(P=0.038 4);Simpson优势度指数与所有环境因子无显著关系。【结论】坡向和土壤速效氮、速效磷、速效钾是导致秦岭南坡中段松栎混交林不同群丛之间物种多样性差异的主要因素。

【Objective】 The species diversity of pine and oak mixed forest community in the middle part of south Qinling Mountains was studied to classify the associations types,and to study the relationships between environment factors and different associations biodiversities.【Method】 24 samples of the pine-oak mixed forest in Houditang and Xunyangba in the middle section of south Qinling Mountains,Shaanxi province were set.Tree shrubs,herbs,and soil characteristics near the samples were investigad.TWINSPAN was used to classify associations,the α diversity index was used to estimate biodiversity,and regression analysis was used to study the relationship between 12 environmental factors and 4 diversity indices.【Result】 Based on TWINSPAN,24 samples were classified into 8 associations,and Pinus tabulaeformis＋Quercus aliena var.accuteserrata association is the most widely distributed mixed type in the research area.The differences between biodiversity indices of 8 associations are big,the change trend of Shannon-Wiener index is same as Patrick index＇s,and the change trend of Simpson index is the same as Pielou index＇s.Exponential regression between Patrick index and 0-20 cm available phosphorus reached significant level（P=0.026 6）,binomial regression between Patrick index and 20-40 cm,40-60 cm available potassium reached significant level（P=0.026 0,P=0.019 6）.Binomial regression between Pielou index and 20-40 cm available nitrogen reached significant level（P=0.045 9）.Linear regression between Shannon-Wiener index and standardization aspect reached significant level（P=0.038 4）.Simpson index and all environmental factors have no significant relation.【Conclusion】 The biodiversity difference among 8 associations was mainly influenced by aspect,available nitrogen,available phosphorus and available potassium.