Relationship between Growth Increment of Azadirachta in dica and Site Condition in Hot and Arid Valley

Azadirachta indica is an excellent multiple purpose tree adaptive to the climate of hot and arid valley.It has played an important role in ecological environment construction and in regional economy development since introduced into China.This paper aimed at giving some evidences of the relationship between growth increment of Azadirachta indica plantation and site conditions basis on the investigating materials of the neem plantation in Yuanmou County.The results of simple regression showed that the height increment of the top tree and mean tree of the plantation increased corresponding to the slope location (from mountaintop to the valley), soil moisture, soil capillary porosity, available soil depth, and rapid available P2O5 with linear function.The results of stepwise variable selection showed that the main factors effecting tree growth were slope location,soil capillary porosity and organic matter contents.The multiple equations were worked out based on data analysis.