Bark peeling does not explain the distribution of epiphytes between six phorophyte species of a tropical dry forest of Mexico

Abstract

Background and aims – Contradictory evidence exists regarding the influence of bark peeling on the distribution of epiphytes among phorophyte species and vertical tree strata. However, there is little experimental evidence. The objectives of this study were to test whether bark-peeling rates differ between vertical strata and between phorophyte species, and whether the peeling rate correlates with epiphyte load among species of phorophytes.Materials and methods – In a tropical dry forest of central Mexico, bark exfoliation rates were measured over a period of 310–322 days in six woody species previously reported with different epiphyte distribution, including Bursera copallifera, B. glabrifolia (phoropytes with high epiphyte load), B. fagaroides, Conzattia multiflora, Ipomoea pauciflora and Sapium macrocarpum (phorophytes with low epiphyte load). In three strata (trunk, inner branches and outer branches) of five individuals of each phorophyte, three areas per individual were marked with paint and with a determined number of small plastic tubes stuck to the bark, in order to easily monitor the speed and quantity of any loss of this marked bark over time. These treatments were replicated on an adjacent pinewood board in order to quantify any loss of painted area or plastic tubes that occurred as a result of deterioration of the marking materials rather than peeling of the marked bark.Key results – The methods used for measuring bark peeling were strongly different. Plastic tubes gave an overestimation of bark peeling in the bark and in the pinewood boards; while paint remained in the pinewood boards, suggesting that paint loss on the bark was caused by peeling. Bark peeling rates differed slightly among the tree species and strata, regardless of whether or not the bark had peeling appearance. No pattern was found between bark peeling rate and the epiphyte load on each host.Conclusions – Our results support previous research which estimated that bark peeling with paint method provides a better estimate of peeling rate. In general, the bark peeling rate was the highest reported in literature for trees in a forest, suggesting that the epiphytes of this forest are adapted to colonize trees with high bark peeling rates. However, this attribute may be less important than others for determining host quality for epiphytes.