关键词: 喀斯特森林, 林隙, 幼苗密度, 时空萌发格局, 茂兰t

Abstract: Seed natural germination in gaps of karst forest in Maolan Nature reserve, Guizhou Province were observed in 4 observation times . Germination number and survival rate of seedlings in gaps, differences in temporal and spatial patterns of seedling emergence were investigated . The results showed that survival rate of seedlings of most species in gaps was high and average survival rate was above 50%. It increased not only the germination rate of tree seeds but also the survival rate of seedlings because of gap formation in karst forest. Seedling density has spatial heterogeneity in different area of gap center, near gap center and gap border. Seedling density of Poliothyrsis sinensis and Ulmus castaneifolia were great in gap center, seedling density of Platycarya longipes, Cladrastis platycarpa, Sapium rotundifolium, Handeliodendron bodinieri, Pistacia chinensis and Carpinus pubescens were great near gap center and seedling density of Acer cinnamomifolium, Viburnum propinquum, Cyclobalanopsis myrsinaefolia and Litsea verticillata were great in gap border where light was slight .Mostof seedlings emerged during the second census. Although germination occurred over the entire observing stage, the total number of seedlings decreased distinctively with the second time . Seedling germination differed temporally among three gap areas. Seedling germination was the most quick in gap center, but in gap border seedlings lagged behind the others. The results showed that it was favorable for seed germination in gap center, but was favorable for seedlings survival near gap center.

Key words: Karst forest