On the other hand, the intrinsic diameter growth rates of mature trees often decrease with increasing stem diameter, as
estimated for fixed competitive effects (Vanclay, 1991). In accordance with this pattern, diameter growth rates often
plateau or decline across the largest size classes for individual canopy and emergent species (Condit et al., 1993; Clark and Clark, 1999), for which light is less limiting. However, the strong increase in mean irradiance with crown height among smaller-statured species may more than offset any declines in intrinsic growth rate after maturity, producing the observed increase in growth rate across the whole size range in all but the emergent life form (Fig. 4). The fact that the largest trees of each life form are mostly comprised of the larger (and hence somewhat faster growing) species of that life form may also contribute to the increase in growth rate across the largest diameter classes.