Studies On Plant Species Diversity Of Robinia Pseudoacacia In Loess Plateau

Selecting the Robinia pseudoacacia plantations forest in Yongshou and Ansai as the study object. Synecology sampling and a biodiversity data were analyzed using the software SPSS. The community structure of the Robinia pseudoacacia industrial plantation and the undergrowth's biodiversity changes, patterns,and driving factors were discussed. The findings of the study will provide theoretical support for improving under-forest biodiversity of the Robinia pseudoacacia plantations forest and their sustainable management. The results as follows:(1) There were 51 species of the Robinia pseudoacacia plantations forest inYongshou. They belong to 49 gengeras,23 families. There were 47 species of the Robinia pseudoacacia plantations forest in Ansai. They belong to 43 gengeras,20 families. The plant of hemicryptophyte and geophytes of plantation forest communities in Yongshou and Ansai were dominant.The phenomenon show the climatic characteristics of hot and much rain in summer,very cold and long in winter.(2) Through typical plots investigation, species diversity indices, richness indices and evenness indices of the shrub layers and the herb layers of the Robinia pseudoacacia in Yongshou County. The results showed that:1) The results showed that the shady slope were significantly greater than on the sunny slope, especially of the Shannon-Wiener index; the slope was positive correlated with species diversity index; 2)Species diversity indices, richness indices and evenness indices of the middle-age forest are all highest; There was a negative correlation between the stand age and species diversity index; 3) Robinia pseudoacacia plantation which density is 1000(stem/hm2) has higher species diversity, the most obvious changes Shannon-Wiener index;There was a positive correlation between the stand age and species diversity index.(3) In Ansai, 1)the trend of species diversity indexes between the shady slope and the stand age showed similar changes with Yongshou;2) Robinia pseudoacacia plantation which density is 1700(stem/hm2) has highest species diversity;There was a positive correlation between the stand age and species diversity index.(4) Comparison of two regions, undergrowth vegetation's families,genera and species of the Robinia pseudoacacia plantations forest in Yongshou are more than Ansai's;Similarity index between plantations communities in these two regions has a higher comparability; the species diversity indexes of the Robinia pseudoacacia plantations forest in Yongshou are more than Ansai's.(5) Using the correlation analysis and the stepwise regression analysis in two regions, The results is:the optimal regression equation model which expressed the relationship between regional difference, species richness index and Shannon-Wiener index were established by the stepwise regression analysis.