Study Of Crown Structure Feacture In The Timber Ginkgo

Timber consumption, especially the precious wood consumption grows dramatically alongwith the economic and social development, which makes it crucial to develop more commercialforest to solve the ever-growing problem on the supply and demand. Ginkgo biloba L. is theprecious commercial tree species which processes profound value on timber, folia and fruit, aswell as ornamenting function. Therefore, in the hope of enhancing timber yield, relationshipbetween the structure factors of ginkgo trees (10a) crown and the tree volumes was studied in thispaper, by using the standard wood method. It is believed to provide theory about selectingfamilies with outstanding timber yield. And the main results are as follows:1. The crown positions significantly affect the branch characteristics. The numbers ofprimary branches (diameter is more than1.5cm) and secondary branches, the primary branchesdiameter and the branch length decrease along the crown vertically. And the angle betweenprimary branch and main stem is between44°-50°2. The crown positions also have significant effects on the folia characters. The decreasing valuesare all found in leaves water content, dry mass, special leaf area and leaf area vertically along thecrown. The leaf area index and the ranking order of water content was found increasingoutwardly in the crown. However, dry mass and the leaf area in horizontal tree crown is: medial＞exterior＞interior. The water content is between （65.88±1.80）%and （68.49±1.70）%and the special leaf area is between （90.39±9.98）cm2/g and （102.67±6.61）cm2/g.3. After stepwise regression analysis, the ginkgo tree volume can be presented by formulawhich concerning several crown factors:Y=0.1068+0.0536X1-0.3599X3-0.0019X4+0.0001X5-0.0249X6-0.0192X7+0.0367X9-0.0013X10+0.0018X11Where: Y is wood volume, X1is leaf area index within, X3is crown volume, X4is crownlength ratio, X5is primary branch amount, X6is secondary branch amount, X7is primary branchlength, X9is canopy surface area, X10is primary branch diameter, X11is primary angle of origin.4. Through the path analysis among all the wood volume dependent crown parameters, thecoefficient of determination suggests that leaf area index within is the key element. And so thepotential large volume ginkgo tree is supposed to process both characters of leaf area indexwithin and big canopy surface area.5.After the principle component analysis and the cluster analysis on the timber volume,diameter at breast height and total tree height,singular ginkgo tree grows faster with crowncharacter as follows: crown length ratio within75.00%, leaf area index within3.09, angle oforigin within53.00°, special leaf area within104.49cm2/g, primary branch number within17,average primary branch length within2.38m, average branch diameter within3.60cm. Amongthose, the crown length ratio, the ratio between the height to area with largest leave biomass andthe total tree height, leaf area index, angle of origin and special leaf area can be the parameters topredict the growing speed of ginkgo trees in each age, and parameters of primary branch number, average primary branch length and average branch diameter can only available for ginkgo tree of10a.