Study on the Succession Characteristic of Ziwuling Community of Loess Plateau

By analysis of Populus davidiana,Betulaplatyp hylla,Pinus tabulaeformis and Quercus liaotungensis community characteristics,the water content,soil density and biomass in hilly-gully region in north of Ziwuling in the Loess Plateau were researched,and the result showed that in the progress of succession,the soil moisture and the number of species was negitive relation and the species individuals' order from large to small was Populus davidiana Betulaplatyp hylla Pinus tabulaeformis Quercus liaotungensis.Because of the succession and terra condition and distribution,the soil construction were improved and the diversity of forest community ground biomass was changed prominently.With the four forest community's age nearly the same,the order of different forest ground biomass of single tree was Quercus liaotungensis Betulaplatyp hylla Populus davidiana Pinus tabulaeformis.