Spatial distribution characteristics of root volume of Caragana and grass compound model

The root spatial distributions were observed at selected typical sample plots within the 5m, 10m and 16 m belt-space caragana -grass compound systems. The spatial distribution characteristics of roots volume in Caragana and grass compound model with different spacing was studied using digging method. The results showed out that the horizontal distribution characteristics of all roots was similar with that of roots(D≥0.5mm).The effect of roots (D≤0.2mm) on the horizontal distribution characteristics of whole roots was mainly in a distence of 1.5m near the caragana with the space distance of 5m and 10m, but the effect range was out of 2.0m and undulantl within spacing distance of 16m The volume of roots was decreased with soil depth. The volume of roots in 0~20cm soil increased as the increasing of the spacing distance. The relation of root volume and the spacing distance could be expressed by function y =ae^bx within the spacing distance of 5m, and the function was y =aLn(x)+b with space distance of 10m or 16m. The root distributed relative evenly within the space distance of 16m and the root vertical distribution was mainly in the depth of 0~20cm. The spacing distance of 16m was a suitable space distance for the Caragana and grass compound model at Siziwang Bnner county.