The spatial habitat heterogeneity hypothesis posits that habitat complexity increases the abundance and diversity of species. In tropical forests, lianas add substantial habitat heterogeneity and complexity throughout the vertical forest profile, which may maintain animal abundance and diversity. The effects of lianas on tropical animal communities, however, remain poorly understood. We propose that lianas have a positive effect on animals by enhancing habitat complexity. Lianas may have a particularly strong influence on the forest bird community, providing nesting substrate, protection from predators, and nutrition (food). Understory insectivorous birds, which forage for insects that specialize on lianas, may particularly benefit. Alternatively, it is possible that lianas have a negative effect on forest birds by increasing predator abundances and providing arboreal predators with travel routes with easy access to bird nests. We tested the spatial habitat heterogeneity hypothesis on bird abundance and diversity by removing lianas, thus reducing forest complexity, using a large-scale experimental approach in a lowland tropical forest in the Republic of Panama. We found that removing lianas decreased total bird abundance by 78.4% and diversity by 77.4% after 8 months, and by 40.0% and 51.7%, respectively, after 20 months. Insectivorous bird abundance and diversity 8 months after liana removal were 91.8% and 89.5% lower, respectively, indicating that lianas positively influence insectivorous birds. The effects of liana removal persisted longer for insectivorous birds than other birds, with 77.3% lower abundance and 76.2% lower diversity after 20 months. Liana removal also altered bird community composition, creating two distinct communities in the control and removal plots, with disproportionate effects on insectivores. Our findings demonstrate that lianas have a strong positive influence on the bird community, particularly for insectivorous birds in the forest understory. Lianas may maintain bird abundance and diversity by increasing habitat complexity, habitat heterogeneity, and resource availability.
Bibliographical noteFunding Information:
We thank Boris Bernal, Salom? P?rez, Abelino Vald?s, Oldemar Vald?s, and Severino Vald?s for valuable contributions to the liana-removal study. Maria Garc?a-Le?n helped coordinate and manage the liana-removal experiment. We thank Cagan ?ekercio?lu and three anonymous reviewers for helpful comments that improved the paper. Financial support was provided by the National Science Foundation (NSF-DEB 1019436, NSF-DEB 1822473, and NSF-IOS 1558093). Logistical support in Panama was provided by the Smithsonian Tropical Research Institute and Marquette University. Authors NLM and SAS contributed equally to the study.
We thank Boris Bernal, Salomé Pérez, Abelino Valdés, Oldemar Valdés, and Severino Valdés for valuable contributions to the liana‐removal study. Maria García‐León helped coordinate and manage the liana‐removal experiment. We thank Cagan Şekercioğlu and three anonymous reviewers for helpful comments that improved the paper. Financial support was provided by the National Science Foundation (NSF‐DEB 1019436, NSF‐DEB 1822473, and NSF‐IOS 1558093). Logistical support in Panama was provided by the Smithsonian Tropical Research Institute and Marquette University. Authors NLM and SAS contributed equally to the study.
- Barro Colorado Nature Monument
- Gigante Peninsula
- habitat heterogeneity hypothesis
- tropical forest
PubMed: MeSH publication types
- Journal Article
- Research Support, Non-U.S. Gov't
- Research Support, U.S. Gov't, Non-P.H.S.