摘要：

Aims Mulun National Nature Reserve is rich in typical natural evergreen and deciduous broad-leaved forest communities.However,little is known about the spatial pattern of vegetation and its relation with environment.Our objective was to investigate the spatial pattern of woody vegetation (DBH ≥ 1 cm) communities and its environmental interpretation.Methods Fifty sample plots of 20 m × 20 m dimensions were established based on microhabitats and vegetation community types in Mulun National Nature Reserve,typical karst cluster-peak depression region.We analyzed data collected on woody plants (DBH ≥ 1 cm) in the plots,spatial pattern of woody vegetation communities and relationships with environmental factors (10 soil factors and 5 topographical factors) using two-way indicator species analysis (TWINSPAN) and detrended canonical correspondence analysis (DCCA).Important findings The forest communities were divided into 11 vegetation groups and were classified into 4 eco-types at the third level by TWINSPAN.The first DCCA axis accounted for the largest fraction of the variation of the ordination and showed gradients of slope direction and major soil nutrients.Along the first axis,the pattern of communities ranged from primary forest with shade-tolerant plants towards secondary and manmade forests with shade-intolerant and pioneer plants,accompanying a shift from shady to sunny slopes,an increase in the ratio of bare rocks in the ground cover and a steady decline in major soil nutrients.The effects of soil environmental factors,spatial factors and their interaction on the total variation of forest communities' pattern were quantitatively partitioned following Borcard et al.and showed that the contribution rates were 21.02% for soil environmental factors separately,18.15% for soil environmental factors coupled with spatial factors,13.16% for spatial factors separately and 47.66% for other undetermined factors.This indicated species coexistence was controlled by both niche differentiation and unified neutral theory of biodiversity.

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