Abstract: 59 species of spermatophyte were found in a 900m2 sample plot of Distylium chinensis community in Maolan karst forest. Among the species, 19 critical species have being reproduced. Reproducing species input an average of 351.1 seeds·m-2 to the soil seed bank every year in seed rain. The number of viable seeds capable of contributing to community regeneration was 150.8 seeds·m-2. Viable seeds of 41 species seeds were found, numbering 2510.5～2646.8 grains·m-2 in the soil seed bank. The kind and number of viable seeds in the seed bank changes with time, in a pattern that largely reflects the recent input of seed from (successionally changing) extant species. The loss of viable seeds from the soil seed bank was 17l.9 grains·m-2 every year: these losses included 21.9 grains·m-2 to germination, 133.5 to predation, 3.2 to rot and 13.3 grains·m-2 to decrepitude. This loss of seeds is 21.1 grains·m-2 in excess o{ the annual seed rain input. At the successional stage sampledthe early seral species no longer contribute to the seed rain but do add to the losses from the seed bank, though none of this loss is via germination.

Key words: Karst, Seed bank, Viable seed, Extant species, Seral earlier species