关键词: 森林地上生物量, 林火干扰, 大兴安岭, LANDIS, 气候变暖

Abstract: Knowledge about how soil seed banks in tropical forests respond to elevational gradients is crucial for predicting how tropical forests adapt to climate change. Soil seed banks of tropical forests in Xishuangbanna were investigated by setting transects and plots at four elevations (800, 1000, 1200, and 1400 m), in which soils were sampled and transported to a greenhouse for seed germination. The results showed that: (1) Seed density and species richness were the highest at 800 m; while the lowest seed density and species richness occurred at 1400 and 1200 m, respectively. NMDS analyses based on Bray-Curtis similarity indices showed great distinctions in species composition of soil seed banks among the 4 elevations. (2) The abundance of nonconstituent species in soil seed banks varied along the elevation gradient; nine species were found at 800 m, while only five at 1400 m. The number of individuals for nonconstituent species peaked at 1200 m. (3) The similarity in species composition between standing vegetation and soil seed banks was low at all elevations (<15%). All of these results suggested that forest soil seed banks respond significantly to the changes in elevation in Xishuangbanna.

Key words: Great Xing’an Mountains, LANDIS, climate warming, forest aboveground biomass, fire disturbance