Effects of tree size and position on pipe model ratios in Scots pine

We investigate how the foliage mass to wood area ratios depend on tree and stand characteristics of previously collected data from Scots pine (Pinus sylvestris L.). Our analysis allowed a separation of the relationship between stem and branch cross-sectional areas and the relationship between the branch cross-sectional area and foliage mass. We studied how these relationships varied within and between stands. The lowest site fertility class had a higher foliage mass to stem area ratio than better sites. The relative height of a tree in the stand (Phi) was the major factor that determined the variation in the relationship between the branch cross-sectional area and the stem cross-sectional area. Models based on absolute height or tree diameter were usually weaker. Models based on Phi were simpler, since no other variables were able to explain between-stand variation in the presence of Phi. We were able to predict changes in the branchiness of the tree but not in the foliage mass supported per unit of branch area.