Revista Chilena de Historia Natural 81 (3): 361-371, 2008
RESEARCH ARTICLE
Light-related variation in sapling architecture of three shade-tolerant tree species of the
Mexican rain forest
The crown architecture of three shade-tolerant tree species (two subcanopy and one mid
canopy) was analyzed in relation to the light regime of the forest understorey. The aim was to examine to which extent shade-tolerant
species variate in their crown architecture. Tree saplings (265) between 50 and 300 cm height, and distributed from understorey to
variously-sized canopy gaps, were measured for 13 architectural traits in the lowland rain forest of Los Tuxtlas, México. The analysis
showed that the three species changed their architecture as light increased but in a different way. No species conformed to the typical
wide-crown type expected for shade-tolerant species, and in contrast they presented some traits of light demanding species. The two
sub-canopy species tended to adopt a crown form between a narrow- and wide-crown type, and the midcanopy species showed more
traits of a narrow-crown type. The horizontal crown area appeared as the more related trait to the light and sapling height. It is
concluded that despite being shade-tolerant, the studied species make use of better-lit environments in the forest understorey. The
crown architecture of shade-tolerant species is not as rigid as originally conceived.
Key words:
actinometry, allometry,
growth type, phenotypic plasticity, tree morphology
