Variation in Crown Light Utilization Characteristics among Tropical Canopy Trees

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Abstract
• Background and Aims Light extinction through crowns of canopy trees determines light availability at lower levels within forests. The goal of this paper is the exploration of foliage distribution and light extinction in crowns of five canopy tree species in relation to their shoot architecture, leaf traits (mean leaf angle, life span, photosynthetic characteristics) and successional status (from pioneers to persistent). • Methods Light extinction was examined at three hierarchical levels of foliage organization, the whole crown, the outermost canopy and the individual shoots, in a tropical moist forest with direct canopy access with a tower crane. Photon flux density and cumulative leaf area index (LAI) were measured at intervals of 0·25–1 m along multiple vertical transects through three to five mature tree crowns of each species to estimate light extinction coefficients (K). • Results Cecropia longipes, a pioneer species with the shortest leaf life span, had crown LAI Conclusion Later-successional tree crowns, especially those with orthotropic branches, exhibit lower light extinction coefficients, but greater total LAI and total light extinction, which contribute to their efficient use of light and competitive dominance.