| Beijing-Tianjin Sandification combating program is an important national ecological project.The purpose of the program is to build a complex vegetation system to improve species diversity on forestation land so as to reduce the hazards of sandstorm and soil erosion.In this study,Setting up 121 sample plots for investigation.The species diversity of sandification combating program in Beijing area was taken as the research object.The relationship between species diversity index and forest classification type,afforestation density,canopy density,biomass,tending measures,site environmental factors was explored.The results show that:(])there was a significant correlation between species diversity index and forest classification type,and the implementation of tending measures had a greater impact on species diversity;(2)The maximum entropy model is used to analyze the site environmental factors affecting the species diversity index of pure cypress forest,Elevation,slope direction,soil available phosphorus content and soil total potassium content are the main factors affecting the species diversity index of pure cypress forest.Increasing soil available nitrogen content and soil total potassium content could significantly improve the species diversity of pure cypress forest;(3)The site environmental factors affecting species diversity index of cypress-broad leaved mixed forest are altitude,slope gradient,soil organic matter content,slope direction,available nitrogen,available potassium and soil available phosphorus content.The effects of slope cutting and corresponding soil elemental upgrading measures are not significant.(4)The site environmental factors affecting the species diversity index of broad-leaved forest are altitude,total phosphorus content,organic matter content,slope direction and available nitrogen content of soil.The effect of measures to improve soil organic matter content is general. |
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