Abstract:

Dynamics of species composition and the correlation coefficients of species in each layer were studied and generation patterns of major tree species were discussed among developmental stages of gaps in Karst forest in Maolan Nature Reserve，Guizhou Province．Along the gap developmental series of 10，20，30 and 40 years，the dominant species in the arbor layer were Diospyros dumetorum，Pistacia chinensis，Handeliodendron bodinieri and Carpinus pubescens．The dominant species in the shrub layer were Ampelocalamus calcareous，Sinosideroxylon wightianum，Mahonia confusa and Drypetes longipes，while the dominant species in the herb layer were Pyrrosia lingua，Lepisorus，，Selaginella uncinata and Elatostema stewardii．As for the liana，Smilax stans，Sabia schumanniana，Dabergia hancei and Sabia paniculata were the common species．In the non-gap stands，there were no dominant species．The similarity coefficients of trees，shrubs，herbaceous species and liana species with different gap stages were 0.31，0.42，0.27 and 0.32，respectively．This indicated that the composition of shrub species remained relatively stable during the past 40 years of gap development，while the composition of herbaceous species fluctuated greatly．Trees replacement patterns could be classified into 4 groups according to quantitative dynamics of seedlings，saplings and trees in different gap stages．

Key words: Karst forest, gap dynamic, species composition, regeneration behavior, generation patterns