Lianas Abundance is Positively Related with the Avian Acoustic Community in Tropical Dry Forests

Branko Hilje,Arturo Sánchez-Azofeifa,Shauna Stack

doi:10.3390/f8090311

Abstract

Dry forests are important sources of biodiversity where lianas are highly abundant given their ability to grow during times of drought and as a result of secondary growth processes. Lianas provide food and shelter for fauna such as birds, but there are no studies assessing the influence of liana abundance on birds in dry forests. Here we evaluate the influence of liana abundance on the avian acoustic community in the dry forests of Costa Rica at Santa Rosa National Park. We selected forest sites with different levels of liana abundance and set up automated sound recorders for data collection, analysis and estimation of the avian acoustic community. When the number of lianas increases, the avian acoustic community becomes more complex. Lianas could provide important direct and indirect resources for birds such as structure for shelter, protection, nesting and roosting, and food. The positive relationship that lianas have with birds is particularly important in dry forests where lianas are becoming highly abundant due to the level of forest disturbance and climate change, especially for some bird species that are restricted to this ecosystem. By validating the number of bird species detected in the recordings with the acoustic complexity index, we found that a higher acoustic complexity means higher species richness.

Highlights

Tropical dry forests (TDFs) are considered important sources of biodiversity and species richness given the wide variety of plant and animal species that have adapted to the unique habitats found exclusively in TDFs [1]
Unlike other plants that slow their growth during the dry season to preserve water, lianas have the competitive advantage of growing during times of drought due to an efficient vascular structure and resource allocation; as a result, liana abundance is often higher in TDFs than other tropical forests [4]
We modeled the relationship of liana abundance and forest biophysical properties such as tree basal area (BA), Plant

Summary

Introduction

Tropical dry forests (TDFs) are considered important sources of biodiversity and species richness given the wide variety of plant and animal species that have adapted to the unique habitats found exclusively in TDFs [1]. Lianas are defined as climbing plants that produce woody tissue and germinate on the ground. These vines lose their ability to support their weight and subsequently rely on external supports, such as trees, to aid their ascent to the forest canopy [3]. As such, they are considered non-structural elements of a given forest. Unlike other plants that slow their growth during the dry season to preserve water, lianas have the competitive advantage of growing during times of drought due to an efficient vascular structure and resource allocation; as a result, liana abundance is often higher in TDFs than other tropical forests [4]. In disturbed forests, an increase in liana abundance and biomass can help to restore the light environment, microclimatic conditions and vegetation structure, creating similar habitat characteristics to the forest interior and, reducing the effects of forest fragmentation on birds [5]

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