Ecological Process of Forming“Black-Soil-Type”Degraded Grassland
Liu Wei; Wang Qiji; Wang Xi; Zhou Li(Northwest Plateau Institute of Biology,The Chinese Academy of Sciences,Xining 810001)Li Youfu Li Faji(Grassland Station of Guoluo County,810001)
This paper analyse plant composition,aboveground biomass,the proportionof good grasses and nutrient element in soil at different degraded grassland in Dari county,Guoluo, Qinghai. The results show: The aboveground biomass at moderately degradedgrassland (MDG) is the highest (50. 3g/0. 25m2), it is the lowest at heavily degradedgrassland (HDG), The proportion of good grasses is the highest at non-degraded grassland(original vegetation) (78. 40% ),the lowest one at HDG,lightly degraded grassland (LDG)and MDG is between the both above-mentioned. The mean density of pikas is the highestat MDG(148 Indivi. /ha),the destroy caused by pikas is very heavy(494m2/ha),they showthe positive correlation (r = 0. 9888, df = 3, 0. 01P0. 001, solid degree of soil decreasewith increasing of the grassland degraded level.