| Abstract Over the last few decades the extent of land-use has been dramatic changed and the vegetation cover has been shifted in the Loess Plateau.For understanding the changes of the rehabilitated grassland on abandoned cropland,vertical distribution of root biomass and root length density were studied by the method of space series replaced time courses.The result showed that the dig sampling method was superior to the root core method in the result of root biomass from soil layer 70 cm to 150 cm.Total root biomass of each succession stage was not increased directly at the beginning stage of succession,but decreased to the lowest point at the second year from abandoned.Between abandonment age 12 and 28 years,the root biomass increased to the first steady state.And then between abandonment age 32 and 60 years,the root biomass approached another steady state.In different soil profile from 0 to 150 cm,the root biomass and root length density of top soil layer(0-15 cm) was the maximum.The variousness of root extinction coefficient indicated that roots trend to distribute in deeper soil layer at the beginning successional stage form 1 to 7 years,and then roots were concentrated in surface soil layer between abandonment age 10 and 22 years,after abandoned from more than 28 years,more roots trended to distribute in deeper soil layer. |
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2010, Vol. 8 