Epiphytes in human settlements in rural Panama

Abstract

Background: An ever-increasing proportion of tropical ecosystems are affected by on-going land-use changes, stressing the importance of understanding how organisms cope with biotic and abiotic challenges outside their natural habitat. An important group in the tropics are vascular epiphytes, whose response to human disturbance is poorly understood.

Aims: Creating a baseline data set of epiphyte diversity in human settlements and assessing differences with assemblages of less disturbed habitats.

Methods: We surveyed the vascular epiphyte assemblages in 25 settlements of south-west Panama along a rainfall gradient. We tested how epiphyte assemblages were affected by human disturbance and climate by comparing our data to that of pastures and forest.

Results: Almost half (238 of 499) of all studied trees hosted at least one epiphyte. Altogether, 10,700 epiphytes of 56 species were found. Rainfall strongly affected both composition and diversity of epiphyte assemblages, whereas geographic proximity did not. In settlements, the species pool was considerably smaller than in pastures and undisturbed forest; however, settlements’ diversity was only significantly lower compared to pastures.

Conclusions: Epiphyte assemblages in settlements had a diminished species pool but diversity per tree was comparable to less disturbed habitats. Unsurprisingly, rainfall seems to be the main determinant of epiphyte diversity in rural settlements.

Keywords:

• epiphyte diversity
• human influence
• isolated trees
• mistletoes
• rainfall gradient
• tropical lowlands

Acknowledgements

We thank Mario Luis Bailon Torres (Smithsonian Tropical Research Institute, Panama) for help with tree species identification. Constructive comments of the reviewers on an earlier version helped to improve the clarity of the paper.

Disclosure statement

No potential conflict of interest was reported by the authors.

Supplemental data

Supplemental data for this article can be accessed here.

Additional information

Funding

Funding was received from DAAD (HE) and Smithsonian Tropical Research Institute (GZ).

Notes on contributors

Helena Julia Regina Einzmann

Helena Einzmann wrote her Master’s thesis on epiphyte assemblages as a function to their host tree phenology. She is currently a Ph.D. student, focussing on epiphyte assemblages in human-modified landscapes to assess their dynamic in fragmented habitats.

Lisa Döcke

Lisa Döcke worked in this project during her undergraduate studies, before writing her Bachelor’s thesis on the green hawker (Aeshna viridis) in 2014.

Gerhard Zotz

Gerhard Zotz, Professor of Ecology at the University of Oldenburg and Research Associate of the Smithsonian Tropical Research Institute, has been studying the ecology of vascular epiphytes for more than 25 years. Research questions range from functional anatomy to global biogeography of this group.