Study On Growth Process Mechanism And Photosynthetic Characteristics In Canopy Of Hybrid Larch Plantation

The research object of this paper is14year old larch hybrid of Jiangshanjiao forest farm in Mu Danjiang. Based on analytic data of20fallen trees and3living trees, with the photosynthetic data collected used the LI-6400photosynthesis system in the fixed sample plots of Jiangshanjiao forest farm, constructed a Crown profile model of the larch hybrid, studied light distribution of crown layers in diffenernt months and change law of photosynthetic rate, analyzed change of each factor which affect hotosynthetic rate and created hotosynthetic rate model of leaf layer. Further studied contribution of all levels branches to tree growth of different crown layers of larch hybrid. This paper makes a detailed research work includes the following content:1. The establishment of Crown profile model. Research from three aspects:the estimate model of crown shape, the estimate model of the number of wheel branches, the space distribution of branches. Based on stair branches data of larch hybrid through field measurement, created and tested optimization model of branch base diameter model and branch length model which reflect crown shape used depth into crown of branch, tree diameter at breast height, tree height and crown diameter. Described distribution of branch angle. For the estimate model of number of wheel branches aspect, created estimate model of number of wheel branches and total branches, wheel branches approximately followed peak and right normal distribution. Branches approximately followed normal distribution in the crown, presented a more and little trend. Under the effective crown, number of branches presented straight decline with the increase of depth into crown of branch.2. The dynamic growth branches estimate model of larch hybrid planted forest. Based on analytic base diameter and branches data of level1branches of Measured the sample tree, bring in age factor as independent variable, used Mitschethch equation as a based equation of branches and base diameter growth, created dynamic growth branches estimate model of level1base diameter and branches.3. The crown layers light distribution research of larch hybrid planted forest. Analyzed photosynthetically active radiation (PAR) distribution of different crown layers parts on different months classic weather conditions(Cloudy Or Sunny). And studied the relation between PAR transmissivity and cumulative leaf area index, extinction coefficient, and analyzed the change rule.4. Used photosynthetic rate data determine by LI-6400photosynthesis system, analyzed the daily variations of photosynthetic rate of different crown layers and new-old branchs of larch hybrid planted forest in different months. And analyzed the change of stomatal conductance, transpiration rate and intercellular CO2concentration which related to photosynthesis. Fited curve of photoresponse of new-old branches and CO2response, compared photosynthesis difference ability of new-old branches through the analysis of the related parameters. Created photosynthetic rate model of single leaf layer, provide the foundation for creat photosynthetic rate model of stand level.5. Used living trees analytical data and photosynthetic data which collected from the spot, calculated contribution of each level branches to tree growth in different layers of larch hybrid, provide the foundation data for the understand of larch hybrid growth.