Relationships between crown dimensions and stem development in Fraxinus excelsior

In this study, the relationships between crown development and stem volume increment of ash (Fraxinus excelsior L.) were considered in the framework of a project where modelling and computer simulation should be used to gain insight into the dynamics of even-aged ash stands. Twenty trees, of various development stages and competition status, were felled and subjected to stem and branch analysis. The relationships established in a previous study between stem elongation, branch growth, and branching angle (based on these measurements), together with the characteristic pattern of variation of stem cross-sectional area increment along the stem (Pressler's Law), allowed the reconstruction of the past development of tree crowns. The quantity of foliage in tree crowns was estimated by a "foliar volume" calculated as the product of crown surface projection area and height growth, for each growing year considered. This foliar volume was used together with a relative foliar volume based on the stem surface area to obtain a prediction equation for annual stem volume increment.