Crown of a Sitka spruce plantation: analysis and stochastic description of the developments of the branching structure.
The number, length, angle, azimuth and compass bearing of whorl and interwhorl branches were measured in 1973 and 1976 for a plantation of P. sitchensis established in 1962 in Scotland. Canopy development appeared to comprise the following phases: (a) a period of small annual ht. increment (a.i.) before 'foliage overlap' (0-6 yr); (b) increased a.i. with development of foliage overlap up to 'crown interlock' (6-11 yr); and (c) stable a.i. with the establishment of a population hierarchy in a.i. (11-15 yr). Stochastic models are presented for the component processes of branch structure development viz. bud production, branch dispersion and branch extension. Branch number production decreased after foliage overlap and became constant for each tree. Branch dispersion (distribution around stem) and branch angle were similar for all trees throughout canopy development. Branch extension appeared to be resource limited and was influenced by branch production in (b) and by the position of the tree in the population hierarchy in (c). From authors' summary.