Architectural differences associated with adult stature and wood density in 30 temperate tree species

Abstract

1 Tree architecture is a major determinant of performance, such as height growth, light capture, and mechanical stability. Studies both in temperate and tropical forests have shown significant architectural differences associated with adult stature and light demand. 2 However, studies in temperate forests have not been as thorough in examining these relationships with respect to phylogeny and ontogeny, thus preventing a complete understanding of the patterns in temperate forests and limiting comparisons of the relationship between tropical and temperate forests. Therefore, we performed a community-level analysis of the relationship between tree form and ecology in a temperate forest with statistical consideration of phylogeny and ontogeny. 3 The height–diameter relationship throughout tree development was asymptotic in most species. Crown diameter and depth increased allometrically with tree height, with no asymptote. The tree height, crown diameter, and crown depth of small trees were estimated using these relationships and were similar to those reported for tropical species. 4 Taller species had more slender stems at any reference size and narrower crowns at small reference sizes, whereas crown depth was relatively independent of adult stature. Light-wooded species had narrower and shallower crowns at medium to large reference heights. Stem thickness was virtually independent of wood density throughout the size range. 5 Our results support the hypothesis that the architecture of short or shade-tolerant species is optimized for light capture and mechanical stability, whereas that of tall or light-demanding species is optimized for height growth. These relationships generally agree with results from studies in tropical rain forests, although considerable differences exist, and may potentially promote the stable coexistence of the species.