Accounting for within species variability in growth and structure of Picea sitchensis through analysis of architectural development

There is considerable variation in growth and structure between individuals of Sitka spruce (Picea sitchensis). Both genetic and environmental factors contribute to this variation and an explanation for their joint effects is given based upon the dynamics of their interaction in the production and utilization of photosynthate by the growing tree. Whole tree attributes, such as high individual biomass production, can be attained by trees with different structures. This can be understood by considering the effects of different architectural and physiological properties on photosynthate production and utilization. Definitions of architecture for tree species have typically focused on branch structure and its role in supporting foliage is implicit. For Sitka spruce the foliage supported by individual modules can vary between individuals, even for modules with the same apparent position in branch hierarchy. Foliage support should be considered explicitly in architectural models that will be used in analysis of the growth process.