[Quantitative classification of natural plant communities in the Saihanba National Nature Reserve, Hebei Province, China]

Quantitative analysis of the relationships between the distribution of natural plant communities and environmental factors was studied using two-way indicator species analysis (TWINSPAN) and detrended canonical correspondence analysis (DCCA) methods, in the Saihanba National Nature Reserve in Hebei Province. The results showed that the natural plant communities in the Saihanba Reserve could be classified into eight types, i.e., Sanguisorba officinalis + Carex heterostachya + Trollius chinensis community, S. officinalis + Elymus sibiricus + Geranium platyanthum community, C. lanceolata + Ophiopogon chingii community, Spiraea pubescens - Tripolium vulgare community, Armeniaca sibirica + S. pubescens - T. vulgare + C. lanceolata community, Quercus mongolica + Betula costata - Lespedeza bicolor + S. pubescens - C. lanceolata community, Betula platyphylla + Populus davidiana - Corylus mandshurica + Rosa davurica - Phlomis umbrosa + C. lanceolata + Thalictrum aquilegifolium community and Picea asperata + B. platyphylla - Rosa davurica + Salix taishanensis var. hebeinica - C. lanceolata + Commelina diffusa community. DCCA analysis indicated that slope position and soil nutrients were the main influence factors for the spatial distribution of natural plant communities in the Saihanba National Nature Reserve. Topographic, spatial and soil factors accounted for 34.02% of the variation of species pattern. Of the variation, soil factors accounted for 15.67%, topographic factors 10.05% and spatial factors 6.00%. In the interactions among all factor combinations (2.30%), the interaction between soil and topographic factors was the largest (0.93%), and the interaction among soil, topographic and spatial factors was the least (0.16%). The unexplained portion accounted for 65.98% of spatial distribution, which might be due to anthropogenic disturbance or interspecific competition.