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Conservation of Vascular Epiphyte Diversity in Shade Cacao Plantations in the Chocó Region of Ecuador

Haro-Carrión, Xavier, Lozada, Tannya, Navarrete, Hugo, de Koning, G.H.J.
Biotropica 2009 v.41 no.4 pp. 520-529
Araceae, Bromeliaceae, Orchidaceae, Piperaceae, agroforestry, canopy, epiphytes, farms, forests, humans, landscapes, plantations, regression analysis, shade trees, soil pH, species diversity, tree and stand measurements, understory, Ecuador
To assess the contributions of rustic shade cacao plantations to vascular epiphyte conservation, we compared epiphyte species richness, abundance, composition, and vertical distributions on shade trees and in the understories of six plantations and adjacent natural forests. On three phorophytes and three 10 x 10 m understory plots in each of the agroforestry plantations and natural forests, 54 and 77 species were observed, respectively. Individual-based rarefaction curves revealed that epiphyte species richness was significantly higher on forest phorophytes than on cacao farm shade trees; detailed analyses showed that the differences were confined to the inner and outer crown zones of the phorophytes. No differences in epiphyte species richness were found in understories. Araceae, Piperaceae, and Pteridophyta were less species-rich in plantations than in forests, while there were no differences in Orchidaceae and Bromeliaceae. Regression analysis revealed that epiphyte species richness on trunks varied with canopy cover, while abundance was more closely related to soil pH, canopy cover, and phorophyte height. For crown epiphytes, phorophyte diameter at breast height (dbh) explained much of the variation in species richness and abundance. There were also pronounced downward shifts in the vertical distributions of epiphyte species in agroforests relative to natural forests. The results confirm that epiphyte diversity, composition, and vertical distributions are useful indicators of human disturbance and showed that while the studied plantations serve to preserve portions of epiphyte diversity in the landscape, their presence does not fully compensate for the loss of forests.