Abstract

A recent article by Midgley and colleagues suggests that large trees give rise to inordinately high stand basal areas because they pack canopy space more efficiently than smaller trees. We argue that this phenomenon bears more relation to the fact that diameter increment is not necessarily accompanied by significant crown expansion during all stages of a tree's life. Using data from a canopy tree population in an old-growth temperate forest, we found that crown area scaled as roughly the 3/5 power of trunk basal area. Rather than reflecting fixed scaling laws, we suggest that this pattern arises because of limited opportunities for crown expansion in dense stands. Old canopy trees in dense stands can thus accumulate large basal areas without occupying a commensurately large canopy area.