Dynamics of underground biomass during natural restoration process of abandoned farmland in Huailai Basin,Hebei Province
ZHENG Qiu-Gong-；Wang-Bing-；Guo-Gao-；Zhang-Hong
1.Research Institute of Forest Ecology,Environment and Protection,Chinese Academy of Forestry,Key Laboratory of Forest Ecological Environment,the State Forestry Administration,100091,Beijing;2.College of Resources and Environmental Sciences,Sichuan Normal University,610066,Chengdu: China
Abstract：Three types of sites were selected to represent three phases of the restoration process with the method of substituting time with space in Huailai Basin,Hebei Province.They were recently abandoned farmland,abandoned farmland colonized by grasses,and abandoned farmland colonized by shrubs.Dynamics of underground biomass during the natural recovery process of abandoned farmland were studied.Results showed that the living roots,dead roots and total roots increased with the recovery process.The roots in the deep layers were most living.The differences among the three communities of the underground biomass were significant in the 0-20 cm soil layer.Perennial species,especially the shrubs had deeper root distribution.Seasonal accumulation of the underground biomass was different among the three communities.After a growth season,the roots were increased on the recently abandoned farmland and the grass colonized farmland,but slightly decreased on the shrub colonized farmland.The characteristics of the underground biomass of the recently abandoned farmland were mainly influenced by Salsola collina Pall.,a shallow rooted species,with noticeable contribution of Glycyrrhiza uralensis.The underground biomass on the grass colonized farmland was mainly composed of perennial grass and forbs.Distribution and accumulation of the shrub community roots were consistent with the shrub species,Wikstroemia chamaedaphre.With exception of the living root on the recently abandoned farmland,distributions of the living roots,dead roots and total roots of the three communities followed the T shape.The pattern of decreasing roots with depth could be expressed by exponent or power functions.The accumulation of roots in the surface soil layers could easily induced competition for nutrients and water.
2008, Vol. 6 
