Tsuga Chinensis Var.Tchekiangensis Seeding And Sapling Regeneration And Analysis Of The Influential Factors In Jiangxi Wuyishan

Population regeneration is an important way for population to achieve sustainable development,but its process is often influenced by biotic factors and biotic factors in the habitat,so that the regeneration presents certain spatiotemporal heterogeneity.The number of population regeneration and individual growth characteristics both are the result of the comprehensive influence of biotic and biotic factors,and the adaption to environment of individuals.Therefore,it is of great significance to explore the relationship between the environment and characteristics of population regeneration.In this paper,Tsuga chinensis var.tchekiangensis was used as an object to explore the3 influence of habitat on the regeneration density and seedling height of young plants.The adaptive strategies and growth rules of the configuration in each habitat were analyzed.The results show that:(1)Through the principal component analysis(PCA)of the important value matrix of the species PCA,the 15 plot were divided into four community types.The community I: Ass.Tsuga chinensis var.tchekiangensis+Cyclobalanopsis multinervis-Camellia fraternal,The community ? :Ass.Pinus taiwanensis+Tsuga chinensis var.tchekiangensis-Clethra cavaleriei var.cavaleriei+Rhododendron mariesii,The community ? :Ass.Carpinus viminea+ Tsuga chinensis var.tchekiangensis-Rhododendron mariesii+ Rhododendron latoucheae,The community ? :Tsuga chinensis var.tchekiangensis+ Betula luminifera-Rhododendron fortunei + Camellia fraterna.(2)The variance analysis showed that the regeneration density of young plants between the four types of community is significantly different(P < 0.05),in which the regeneration density of the community II was the largest followed by,the community III,the community IV and the community I had the lowest regeneration density.combined with the static life table we found the mortality rate of seedlings and sapling in community II were 7%,7% respectively,and were 7% and 7% respectively,the life expectancy(1.87,0.96)was the highest in community II.The mortality rate of seedlings and sapling in the community I were 37% and 58% respectively,and they were 46%,86%,the life expectancy was the lowest.The path analysis of the forest structure and the regeneration density of the young plants showed that the stand basal area,the density of the mother trees and the basal area of the arbor trees indirectly depressed the growth of the seedlings,while the basal area of the deciduous trees had a significant positive effect on the occurrence of the seedlings.The density of the stand and the basal area of the shrubs had no significant effect on the saplings.The total effect ofseedling density was not significant,But Stand density and basal area of shrub significantly promoted the density of sapling.And the other stand factors had no significant effect on the regeneration density of sapling.The density of mother tree has a significant inhibitor effect on density of small tree,while the total effect of stand density is not significant.(3)RDA analysis of the environmental factors and the two matrix of the sample plots showed that the first axis interpretation was 47.01% and the second axis interpretation was 4.69%.The distance between the nearest mother tree and plot center,the number of the mother trees and the coverage of the ground grass were significantly related to the first axis and the density of the sapling plants.The regeneration density showed a normal distribution on the altitude gradient,and the best regeneration was at 1500-1800 m elevation.In this study,litter thickness,percentage of bare rock,slope,stand density had no significant effect on seedling density.(4)The analysis of sapling configurations in three typical habitats showed that there was no significant difference between the three habitats of the young shoots and the height of undergrowth in the undergrowth was significantly higher than that in the forest and the road margin,and the crown length had no significant difference,and the canopy rate under the canopy rate was significantly lower than that in the forest and the road margins.There was no significant difference in canopy length between the first branches and the middle and lower parts of the canopy.The number of shoot length and the number of branches on the upper layer were significantly higher in the upper layer than in the middle and lower layers,while there was no significant difference in the annual branch length in the forest margin,and the lower layer of the upper branches was significantly lower than the upper middle layer.The number of primary branches in under story habitat is mainly distributed in the middle and upper layer,and the number of primary branches in forest edge and road habitat is mainly distributed in the middle and lower levels.The branch angle of the first order branches in the same habitat gradually increased with the increasing of DINC,and there was no significant difference in the angle of branches at the upper level of each habitat.(5)The variation of the crown shape will affect the photosynthetic efficiency(photosynthetic efficiency)of plants,thereby indirectly affecting the growth of plants.Through the comparision of the growth increment of breast diameter and height in the forest and the forest margin,we found that the growth increment of breast diameter of the young trees in the forest in 5 years(0.558cm),10 years(1.242cm),and 15 years(1.854cm),was significantly lower than that of young trees in 5 years(1.2cm),10 years(3.004cm)and 15 years(4.148cm)in the edge of forest.The average DBH growth ofsapling both in forest and forest edge was highest in tenth years,which were 0.13cm/a and 0.30cm/a respectively.The total growth of sapling sin the two habitats was significantly differently only in fifth years.The maximum growth rate of the sapling both in the forest and forest edge reached highest in the tenth year,which was 0.11m/a and 0.21m/a respectively.In a word,the population dynamics of the seedling population in the south of in Jiangxi Wuyishan National Nature Reserve is closely related to the regeneration of the seedlings and the micro-habitat,and the "environmental screening" has a profound effect on the population dynamics.And plasticity changes of shoot shape have taken place in different environments,That is a kind of ecological adaptation to the environment,which result to the difference of plant growth.