Crown Architecture And Dynamics Of Branch Growth In A Larch Olgensis Plantation

Models for simulating locational distribution of total branches, both along and around the bole, and for estimating crown profile of primary branches within live crown were developed in a 26-year-old Larix olgensis plantation based on the circular branch analysis technique. Characteristics and dynamics of basal diameter and length growth of primary branches within live crown were also studied in the paper.A linear model expressed as function of DBH and total height (HT) was developed to predict the total number of branches per tree within a crown. The Weibull distribution was used to describe the vertical distribution of branches and performed well to estimate the relative frequencies of branches by relative depth into crown (RDINC) class. All of braches for entire sample trees, analysis of branch azimuths indicated that a uniform, or rectangle, distribution was appropriate to reflect branching pattern around the bole. Crown profile models were developed from branch and tree variables, including branch diameter, branch length, angle of origin, and branch chord length. These attributes of primary branches for a specified tree were increased with increasing the depth into crown (DINC). DBH and HT were adequate variables of tree for summarizing the effects of external conditions on crown profile. The number of years without the production of annual ring (missing rings) in the branches within the live crown along the stem is continuously increased with increasing depth into crown (DINC), ranged from 0 in the upper crown to 5 in the lower crown with a mean of 0.7 year. Diameter increment of branches decreased gradually with increasing branch age after they were formed. The annual increment of branch length existed a peak at first 1 ~3 years and then decreased continuously with increasing branch age. Growth models of branch diameter and branch length were developed from branches age, including tree variables of DBH and HT. Overall, the models developed in this study were suitable in describing the crown profile, succeed in representing the growth trends in branch diameter and branch length and reasonable in reflecting the growth characteristics of primary branches. They can be applied to simulate the dynamics of live crown.