Studies On The Radial Growth And Regeneration Of Two Main Species In Wanglang National Nature Reserve, Sichuan Province

Picea purpurea forest and Abies faxoniana forest are two major forest types in Wanglang National Nature Reserve. Radial growth and regeneration were used to explore the rhythms of growth and regeneration and the responses to the climatic factors of Picea purpurea and Abies faxoniana in the study area. The aim was to provide scientific basis for conserving the community and predicting the influence of climate change on tree growth and distribution.For radial growth study, two sample plots about Picea purpurea and Abies faxoniana were set up in the primary forests to core tree-rings, and then chronologies were established and the correlation relationships between RES chronologies and climatic factors were analyzed. For regeneration study, population dynamics of Picea purpurea and Abies faxoniana were analyzed by creating the age-specific life table, and the correlation relationships between climatic factors and regeneration of the two species were analyzed.The main conclusions from radial growth study were as follows:1. The tree-ring widths of Picea purpurea and Abies faxoniana were sensitive to the suppression and release. Release events in radial growth occurred once or more in most of trees during the last 230 years. The mean radial growing rate of Picea purpurea and Abies faxoniana were 0.853mm/a and 1.492 mm/a.2. The chronologies of the two species included a lot of climatic signals, and they can be used in dendrochronology research. The statistical characteristics about the RES chronologies of the two species were better than those of STD chronology, which indicated that RES chronologies retained more high frequency oscillation information.3. Temperature was the major climatic factor influencing the radial growth of Picea purpurea and Abies faxoniana. Temperature in previous grow season (July, August) were negatively correlated with the radial growth of Picea purpurea and Abies faxoniana (P<0.05). While the temperature in current October had a positive correlation with the radial growth of Picea purpurea and Abies faxoniana (P< 0.05). Besides, the temperature in current June had a positive correlation with the radial growth of Picea purpurea (P<0.05). The precipitation in previous December had a negative correlation with the radial growth of Picea purpurea, but the precipitation in current January was correlated with the radial growth of Abies faxoniana positively. The relationship was verified by single year analysis.The main conclusions were as follows after studying on the regeneration:1. The survivorship curve of Abies faxoniana belonged to the type of Deevey-â…¢. Two peaks of mortality were existed in the lifespan; one was from seedlings to young trees (0-30 years). Saplings banks of Abies faxoniana were rich with a high mortality ratio. However, Saplings banks of Picea purpurea were poor with a low mortality ratio.2. Temperature was a key factor that influenced the natural regeneration. There was a positive correlation between regeneration and temperature in August and December and annual temperature. The mean annual precipitation has a low correlation with the regeneration. The accumulated sunshine hours were negatively related to the regeneration of Abies faxoniana.