Abstract: Taking wild grass ground as the reference,this paper studied the dynamics of Sophora davidii population on the sunny,semi-sunny and semi-shady slopes of hilly region in Loess Plateau after 30 years closed for reforestation,and analyzed the age structure,spatial distribution pattern,life table,and survival curve of the population.The results showed that S.dvidii population in the region belonged to progressive type,with more young and less old individuals.Among the three habits,semi-sunny slope had the highest population density.The survival curve of S.dvidii population was approached to DeeveyⅡtype.The population pattern was of clustered distribution,with the aggregating intensity increased with age.Water and light were the main environmental factors affecting the recovery and development of S.davidii community.The better recovery of S.davidii population suggested that the measures of closing the land for reforestation were efficient.

Key words: Karst process, Soil carbon, Carbon cycling