Vascular Epiphyte Assemblages on Isolated Trees along an Elevational Gradient in Southwest Panama

Calixto Rodríguez Quiel,Gerhard Zotz

doi:10.3390/d13020049

Abstract

Ongoing destruction of tropical forests makes isolated pasture trees potentially important for the persistence of original forest dwellers such as many vascular epiphytes. We studied epiphyte assemblages on 100 isolated trees at ten pasture sites in southwest Panama along an elevational gradient ranging from 140 to 1240 m a.s.l. We analysed epiphyte species composition (richness, similarity) and registered climate and host trait variables of potential influence on their occurrence. We found a total of 5876 epiphyte individuals belonging to 148 species. Epiphyte abundance, species richness and diversity all varied about 4-fold among the 10 sites, with a high similarity of epiphyte assemblages among sites. Two sites at 870 and 1050 m a.s.l. did not fit into the overall elevational trend of increased abundance, species richness and diversity. However, all three measures were significantly correlated with humidity as the independent variable. This highlights that a gradient in humidity, and not elevation as such, is responsible for the typical elevational changes in epiphyte assemblages, so that special local conditions may lead to deviations from expected patterns. Our documentation of current elevational diversity patterns also provides a baseline for the study of long-term changes in epiphyte assemblages in anthropogenically modified landscapes.

Highlights

IntroductionDespite their important role as the habitat of at least half of the global terrestrial biodiversity, tropical forests keep decreasing in cover due to human activities [1,2]
We describe the variation of β-diversity in the elevational gradient and the effects of some important biotic and abiotic variables that typically have a direct effect on epiphyte assemblages [14,23]
Our results not fulfil the expectation of aup steady increase because neithe epiphyte abundance anddid species richness with elevation to a maximum at intermedia epiphyte abundance and species richness with elevation up to a maximum at intermediate elevations [19,20,21,28,30] is usually explained by an increase in water availability

Summary

Introduction

Despite their important role as the habitat of at least half of the global terrestrial biodiversity, tropical forests keep decreasing in cover due to human activities [1,2]. There is an increasing need for land to provide food, living space and other resources, which currently represents the principal threat to tropical biodiversity [3,4,5]. Land use change rather than climate change or invasive species is the most important cause of decreasing biodiversity [7]. Knowledge of the current status of tropical biodiversity in modified landscapes will allow us to establish management plans for conservation and sustainable development beyond primary forests [8]

Methods

Results

Discussion

Conclusion