Abstract: Based on study of component,structure,function of degraded Karst forest in the natural restoration process in Maolan National Reserve of Guizhou Province,three evaluation indexes such as restoration potential degree (RP),restoration degree(RD),restoration speed(RS) and their calculating methods were proposed.Variation and comprehensive evaluation of RP,RD and RS of community feature indexes which reflected component,height,coverage,seedlings/total trees,dominance and biomass were analyzed.The results showed that there were the highest RP between the lower and the next to higher succession stage,so as that natural restoration of degraded community was a process in which lower community was replaced by its next higher one successively.There were higher RP but lowest RD and slower RS in the early stage;the highest RP,the fast RS and moderate RD in the mid-stage;the lowest RP,the slowest RS and the highest RD in the late stage.The RP of community was slower than that of community feature indexes,and the RS of total function was slower than its part one.In community feature indexes,RS of component,height,coverage,seedlings/total trees and dominance were faster than that of biomass,the fact indicated that RS of structure was fast than that of function.The natural restoration strategy was that the regeneration in early stage changed into the community structure adjustment in mid-stage,and finally to the structure and function coordination or improvement in late stage.The normal community component,physiognomy,structure could be presented after 40 to 50 years natural restoration,but it take a long time to restore total community function.

Key words: Degraded Karst forest, Natural restoration, Restoration potentiality, Restored degree, Restoration speed