The Relation Between Fine Root Of Robinia Pseudoacacia Forest And Forestland Soil Moisture

The root (fine root) distribution characters of artificial R. pseudoacacia forest and forestland soil moisture during the growing season were respectively investigated by using soil-drilling and neutron instrument at sunny and shady slope sites in semi-moisten and semi-arid regions of Loess Plateau. The aim was to analyse the relation between soil moisture and root distribution by the results of survey soil moisture current level, dynamic variation during the growing season, and the root distribution character at different slope sites in different water ecological areas, and then to discuss the phenomena of dried soil layer in Loess Plateau. The results showed as follows:â‘ soil moisture was at different current levels at different sites. Soil moisture condition in semi-moisten region was better than in semi-arid region; soil water content at shady slope was higher than at sunny slope in each water ecological area, soil water content gap between sunny and shady slope sites in semi-moisten was obviouser than in semi-arid region.â‘¡soil moisture effect on root spatial distribution character. Root spatial distribution and root surface density value at shady slope sites were larger than at sunny slope sites in each water ecological area, they were not enough larger in semi-moisten than in semi-arid.â‘¢soil moisture dynamic variation, during the growing season,across soil profile can be divided into three layers: Soil moisture active layer, soil moisture utilization layer, and soil moisture stable layer. The depth of each layer was different at different sites.soil moisture utilization layer was the primary layer of root effect on soil moisture, so soil water content of this layer changed with the growing season, that is, at the beginning of the growing season, soil water content of this layer was highest; soil water content of this layer was cuting down, along with the time pass away, at the end of the growing season, soil water content of this layer was lowest. With the soil depth going down, soil moisture dynamic variation became no more obvious; soil moisture became stable at some certain soil depth layer. Thus, root only effect on soil moisture at some limited soil layer, this limited soil layer was at 2.7m under soil surface at shady slope and 3.3m under soil surface at shady slope in semi-moisten region. In semi-arid region, this limited soil layer was at some certain limited layer under 3.5m.â‘£according to the relation between soil moisture and root, dried soil layer was resulted of special deposit history of loess soil, and dryclimate ,little rainfall,the improper vegetation...