Modelling the structural growth of Scots pine with implications for wood quality

A model for simulating the growth and development of individual Scots pines (Pinus sylvestris L.) is presented in terms of three-dimensional structure of the tree as determined by the influence of local light conditions on br anch growth, with implications for the properties of the wood. The basic co mputational unit for structural growth is the shoot. Each shoot produces ne w shoots with dimensions related to the amount of direct and diffuse radiat ion intercepted in the parent shoot and supplied by other shoots in the cro wn. The calculation procedure utilises the spatial distribution of shoots p roduced by the growth process (location, azimuth, inclination), and the str ucture of the shoots determined in terms of the density, angle and length o f the needles. The allocation of tree biomass amongst the needles, branches and stem is basically related to the allocation of the growth of forming s hoots between the shoot axis and the needles under the control of the hiera rchical position of the parent shoot, branch age and the height of the tree . The growth, death and pruning-off of shoots and branches are modelled ove r the life span of the tree using time step of 1 year, taking special care to identify the location of green and dead knots in the wood. The propertie s of the stem are further described in terms of the stem form, wood density and heartwood, which are modelled in the context of the overall growth of the tree. The computation produces the three-dimensional distribution of ri ng widths, density and heartwood in the stem, i.e. from the pith to stem su rface and from the stem base to tree top. The model produces quite a realis tic crown and stem structure for simulated Scots pines regardless of the li fe span of the tree. Furthermore, the model is capable of calculating quite accurately, e.g. average wood density values for any section of wood withi n a tree. (C) 1999 Elsevier Science B.V. All rights reserved.