Root architecture and allocation patterns of eight native tropical species with different successional status used in open-grown mixed plantations in Panama

Abstract

We investigated biomass allocation and root architecture of eight tropical species with different successional status, as classified from the literature, along a size gradient up to 5 m. We focused on belowground development, which has received less attention than aboveground traits. A discriminant analysis based upon a combination of allocational and architectural traits clearly distinguished functional types and classified species according to successional status at a 100% success rate. For a given plant diameter, the pioneer species presented similar root biomass compared to the non-pioneer ones but higher cumulative root length and a higher number of root apices. A detailed study on the root system of a sub-sample of three species showed that the most late-successional species (Tabebuia rosea) had longer root internodes and a higher proportion of root biomass allocated to the taproot compared to the other two species (Hura crepitans and Luehea seemannii). Most pioneer species showed a higher leaf area ratio due to a higher specific leaf area (SLA). We conclude that the functional differences between pioneer and non-pioneer tree species found in natural forests were maintained in open-grown plantation conditions.

This research was made possible by a Discovery Grant from NSERC (Canada) as well as help from the “Ministère de la Recherche, de la Science, et de la Technologie” of the province of Québec, Canada. LC was supported during 2007 by a “Juan de la Cierva” contract from the Spanish Ministry of Science and Education.