Root biomass distribution of natural grasslands with different enclosing years in the Loess Plateau

An investigation on root biomass distribution in 0-80 cm soil layer of natural grasslands with different enclosing years was conducted in Yunwu Mountain, by employing soil core method. The correlations among root biomass, soil water content and soil bulk density were also studied. The results indicated that: 1) Root biomasses centralize in 0-30 cm soil layer and decrease with the increasing of soil depth for all natural grasslands with different enclosing years; 2)Root biomass increases with the increasing of enclosing year, and reaches the maximum value in grassland with a 30 years enclosing; 3)With the increasing of enclosing years, soil water content of grassland increases with a S-type, soil bulk density of topsoil decreases, and the structure of soil is improved; 4)There is no significant correlation between root biomasses and soil water contents of 5 kinds of enclosed grasslands.