Abstract: Based on the investigation on gaps and non-gap stands of the Karst forest in Maolan National Nature Reserve , Guizhou Province, the quantitative characteristics and dynamic changes of seed rain and seed bank in gaps were analyzed . The results showed that the total seed rain number was reached 117 .4±32 .6 seeds􊄯m2 during the period of observing , among them, the number of immature seed , damaged mature seed and germinable mature seed was 56. 3±10. 3 seeds/m2 , 15 .7±4 .7 seeds/m2 and 45 .4±8. 2 seeds/m2 , respectively . It suggested that it was rich in seed for gap regeneration . Seed rain in gaps had space-time heterogeneity characteristics and it would affect regeneration pattern of gap plant deeply. From the gradient of gap center to non-gap stand , the density of seed , number of species and Shannon-wiener richness index of coarse debris layer was reduced gradually , but it was increased in soil . The density of seed in gap center , near gap center and gap border area were 2415±639 seeds/m2 , 2218±421 seeds/m2 and 1815±311 seeds/m2 , respectively. It showed that gap plant had good regeneration latent. In gaps and non-gap stands, Jaccard similarity index of seed between coarse debris layers was the greatest, 5 - 10 cm was second and 0 - 5 cm was small. Jaccard index between soil seed bank and present community was great in coarse debris layer , but decrease with the soil depth both in gaps and non-gap stands . The results showed that soil seed bank was the main resource of gap regeneration in karst forest of Maolan , it contributed to gap regeneration greatly .

Key words: Karst forest