Species Composition and Spatial Pattern of Ormosia boluoensis of Extremely Small Population

Abstract:

In order to protect Ormosia boluoensis resources, the community characteristics, including species composition, population structure, spatial pattern, intraspecific association and interspecific relation with dominant species were studied based on 0.6 hm2 fixed plot in Xiangtoushan National Nature Reserve in Guangdong Province, which is the concentrated distribution area of O. boluoensis. The results showed that there were 4 503 individuals with DBH (diameter at breast height)≥1, belonging to 84 species, 57 genera and 38 families. The dominant species of the community were Castanopsis eyrei, Rapanea neriifolia, Symplocos congesta, Michelia maudiae and Syzygium buxifolium. The importance value of O. boluoensis was only 1.84, and its diameter class structure showed an inverse ‘J’ type. For spatial pattern, Ormosia boluoensis showed an aggregated distribution at scale of 0-22.1 m and a random distribution at scale of 22.2-30.0 m. As for interspecies relationship, there was no obvious association between O. boluoensis and Castanopsis eyrei and only a weak negative correlation with Syzygium buxifolium on some scales. There was a negative correlation with Symplocos congesta, while a positive association with Rapanea neriifolia and Michelia maudiae. There was positively strong associated between seedlings and adult trees of O. boluoensis at scale of 0-3.7 m, and positively associated between young trees and seedlings at scale of 0-5.9 m, but the association between adult and young trees trees was weak. Therefore, the spatial distribution pattern of O. boluoensis was affected by negative density restriction, seed diffusion limitation and habitat heterogeneity. So, proper seedlings transplantation and thinning in the community could be implemented in the later management.

Key words:community characteristics; Species composition; Diameter class structure; Spatial distribution pattern; Plant species with extremely small populations; Ormosia boluoensis.