Response of Soil Quality to Artificial Vegetation Restoration Patterns in the Arid Area of Northern Weihe River Basin VARIATION WITHIN TREE OF WOOD ANATOMICAL PROPERTIES AND BASIC DENSITY OF I-214 POPLAR IN BEIJING AREA AND THEIR RELATIONSHIP MODELLING EQUATIONS EFFECTS OF DIFFERENT PLANTING DENSITIES ON THE GROWTH,OUTPUT AND WOOD PROPERTIES OF EUCALYPTUS UROPHYLLA Population density of Eucalyptus urophylla plantation Effect of soil temperature and moisture on soil CO2 efflux in a Pinus tabulaeformis forest