[Niche characteristics of dominant populations in natural forest in north Guangdong].

Two communities of the natural evergreen forest in Luoba Nature Reserve, North Guangdong, each represented by a 2500 m2 plot, were surveyed with Tree-layer-frequency method. Based on these data, the niche characteristics of 12 dominant populations, i.e., Castanopsis fargesii, Pinus massoniana, Schima superba, Liquidambar formosana, Diospyros morrisiana, Myrica rubra, Castanopsis lamontii, Adinandra milletii, Castanopsis eyrei, Elaeocarpus silvestris, Daphniphyllum calycinum, Neolitsea chuii, were described and analyzed, with stand layer as the resource state and tree abundance as the resource state descriptor of niche. The results indicate that most of the shade-tolerant tree species have higher niche breadth values, while the intolerant tree species have the lower ones, with zero value for Pinus massoniana and Liquidambar fomosana, which is in accordance with the declining status of the two species in the community. All the dominant populations, both shade-tolerant and intolerant, showed some adaptation to the community environment. 54.5% of the population-links had a niche similarity over 0.5, and 51.5% of them had a niche overlap over 0.2 in community 1. Niche characterization combined with conventional Tree-layer-frequency method could better determine the status and regenerating potential of tree species in the community. On the other hand, measuring tree abundance in different stand layers as the resource niche could demonstrate tree's requirement for the habitat. Variations in tree composition result in varied niche breadth, which lead to the variations of niche similarity and niche overlap values.