Abstract:

Abies faxoniana forests are one of the major types of sub-alpine dark coniferous forests on the eastern Tibetan Plateau. In the mountainous areas of the upper Minjiang River, it is distributed between altitudes of 2 800-3 800 m a.s.l and usually forms the upper timberline on shaded slopes. To explore the survival status of A. faxoniana populations, ten plots (20 m×20 m) were investigated and analyzed in Gonggangling (33°02′39″ N, 103°43′11″ E). Individual ages were determined using WinDENDRO system or by counting tree branches. Time-specific life tables or vertical life table curves of survival-mortality based and hazard based age structures were drawn. The results showed that: 1) The survival curve of the population conformed to the type of Deevey-Ⅲ; 2) With an increase in the population mortality ratio and a decrease in the survival rate, the mortality ratio greatly increased in ages 0-40 years, reaching 89.7%; 3) There existed two peaks of mortality in the lifespan, one was from seedlings to young trees (0-40 years) and the other in the adult stage (180 years). It is suggested that the mortality rate of A. faxoniana seedlings is impacted most by temperature, wind, snowpack depth, water and other environmental factors.

Key words: Population of Abies faxoniana, Timberline, Time-specific life table, Survival curve, Spectral analysis