Abstract:

Sladenia celastrifolia has a scattered distribution in Southwest China, especially in Yunnan Province. However, characteristics of many populations have been largely altered by increasing human activities. Using age-diameter relationships, we analyzed the age structure, the life table and the survival curves of two populations of this species, which have been affected by human disturbance to different degrees. In the heavily disturbed population, there were fewer young-aged individuals. The individuals of the age class Ⅰ account for only 12.7%, whereas those of the age class Ⅱ, Ⅲ, and Ⅳ together account for 80.3% of the total individuals of the population, indicating a declining population. In contrast, the age structure of the less disturbed population appeared to be stable with sufficient numbers of young-aged individuals. The life tables of the two populations were different: the death rates of the age class Ⅰ and Ⅱ were negative, indicating a shortage of young-aged individuals. The survival curves of both populations were characterized by high death rates of young-aged individuals, while the death rates of all age classes of the less disturbed population were stable. The age structure and dynamics of the two populations of this species are similar to those of some other endangered species in China, such as Liriodendron chinense and Cathaya argyrophylla. Although S. celastrifolia has not been regarded as an endangered species until now, it has attributes typical of an endangered species according to the standards of IUCN. Therefore, more attention should be paid for the conservation of this species such as establishing nature reserves in its original habitat as well as ex-situ conservation efforts.

Key words: Human disturbance, Population quantitative characteristics, Age structure, Life table, Survival curve