| Using Keteleeria davidiana natural pure forest and mixed forest in Guangxi Yachang Forestry Farm in the high altitude mountains as the research object, the tree growth and the population analysis of K. davidiana(such as distribution pattern and evolution trend of size, the age, etc.) were analyzed, and the regression model analysis of K. davidiana population biomass was established and carbon storage was estimated, which could provided a scientific basis for the sustainable management of K. davidiana populations in Yachang Forestry Farm. Research results showed that:(1)Tree growth:The average tree height, DBH and volume growth of K. davidiana in the tree layers were 14.24 m,33.19 cm and 0.4761 m3. the fast growth stage of Tree height and DBH were 1～12a and 6～11arespectively, and the growth curve and the average growth curve intersected in 14-15a. Annual volume growth reached the maximum value of 0.0298 m3·a-1, then decreased gradually.(2) In K. davidiana pure forest, more grade 1 seedlings (more than 1 year seedling) were found, but less grade 2 and grade 3 trees, could be correlated with the low light penetration through the tree layer. In mixed forest of K. davidiana, more class 1, grade 3, grade 4 were found, mainly accounted for 18.85%,26.05%,43.95% respectively. The seedlings and saplings grew naturally in the mixed forest under high penetrating light.(3)The age structure analysis of K. davidiana population showed that the age stage of natural pure forest was in decline, while in the natural mixed forest was growth or between the growth and stable.(4)The tree layer’s biomass of K. davidiana population in the pure forest and mixed forest were 12.27 t/hm2,54.76 t/hm2 respectively,the former was greater than the latter. The biomass pattern was basically the same:trunk>branches>bark>leaf>root pocket> lateral root. Biomass ratio was as follows:Pure forest as 43.61%,33.40%, 8.92%,8.13%,3.85% and 2.09%; mixed forest as 43.92% and 33.20%, 8.98%,8.03%,3.92% and 1.93%.(5) The average carbon contents in different organs of tree layer inK. davidiana were between 464.91-512.62 g/kg. In pure forest and mixed forest, the carbon storage in tree layer of K. davidiana population were 61.77 t/hm2 and 28.94 t/hm2 respectively, the former was 2.13 times of that in the latter. |
