Research on structure of typical forest community and characteristics of species diversity of Zhouzhi,Shaanxi Province

【Objective】 This paper carries research on structure of typical forest community and characteristics of species diversity in Yangjiagou,Zhouzhi Laoxiancheng Nature Reserve,to provide theoretical basis for vegetation restoration and reconstruction,biodiversity protection and cataloging.【Method】 We classified the forest community by two-way TWINSPAN,analysed the community diversity and its changes with the elevations of the gradient on species richness S,Shannon-Weiner index,Simpson,Pielou index and evenness index.【Result】 The 28 plots in research area can be divided into 9 community types;the order of the community diversity is Pinus armandii Corylus ferox+Populus purdomiiUlmus bergmannianaQuercus serrata var.brevipetiolataQuercus aliena var.acutiserrataPopulus davidiana+Betula utilisPinus tabulaeformisBetula albo-sinensisQuercus spinosa;the 9 forest communities have vegetation resources in 243 species of which pteridophyte has 4 families 4 genera 4 species,gymnosperm 2 families 4 genera 5 species,angiosperm 58 families 151 genera 234 species.Species diversity changes regularly along altitudinal gradients,which shows a rising tendency between 1 525-1 920 m,then a downtrend between 1 920-2 340 m.【Conclusion】 The forest communities in research area have been disturbed intensely by people and livestock,causing the degradation in community structure and function of ecological system and bio-diversity's reduction,so effective measures should be taken to decrease the artificial interference and damage to community structure and function of ecological system.