湖北林业科技

Abstract:We studied the changes of soil bulk density in different site types and different degrees of soil depth，and investigated the difference of physicochemical properties of soil in semi arid valley region of Lhasa in order to provide a theoretical basis and reference for the restoration of degraded ecosystem and vegetation reconstruction in this region.The results showed that the soil bulk density value of different site types was the upper part of sunny slope (1.35 g·cm-3) ＞the low water level of flood land（1.33 g·cm-3）＞the lower part of sunny slope (1.32 g·cm-3) ＞the high water level of flood land (1.31 g·cm-3) ＞the upper part of shady slope（1.27 g·cm-3）＞the lower part of shady slope（1.22 g·cm-3）＞terrace（1.08 g·cm-3）;The soil bulk density in sunny slope and flood land was higher than others;On the aspect of the slope, the soil bulk density in sunny slope is higher than the shady slope;At the same slope, the soil bulk density in the upper part is higher than the lower part and the bulk density of the surface soil (0～20 cm) is lower than that of the deep soil (40～60 cm); The spatial structure of soil in the study area showed that the soil bulk density increased with the increasing of soil depth;The variation range of the variation coefficient (C.V.)of the soil bulk density of each soil layer was between 0071~0079 and all of them belonged to weak variation.