Soil Water-holding Capacity of Wanglang National Nature Reserve in Western Sichuan

In this paper,studies were made of the soil water-holding capacity of 7 typical ecosystems,which were grass land (dominated by Deyeuxia scabrescens),shrub (dominated by Salix paraqplesia),broadleaf forest (dominated by Betula platyphylla),mixed forest (dominated by Betula spp.and Abies faxoniana),fir forest (dominated by Abies faxoniana),spruce forest (dominated by Picea purpurea) and cypress forest (dominated by Sabina saltuaria) in Wanglang National Nature Reserve (WNNR)in the subalpine of western Sichuan by field survey and ring shear testing,and the assessment were conducted on the regional soil water-holding capacity in Wanglang National Nature Reserve (WNNR).The results indicated that in the studied 7 ecosystems,the soil bulk density increased with the increasing of the depth while the soil water-holding capacity decreased with the increasing of the depth significantly.Ecosystems largely affected the soil bulk density and soil water-holding capacity,and the soil of mixed forest had the smallest bulk density and the largest water-holding capacity.The soil of WNNR could hold 90 870 361 t in all of the studied 7 ecosystems,which were contributed by grass land and mixed forest.Therefore,the contribution to regional soil water-holding depended on the size of a given ecosystem and its water-holding capacity.It was also indicated that ecosystem management for increasing the water-holding capacity should be strengthened to establish the mixed forest,and much attention should be paid to the ecosystem structure and removing human disturbance.