Effects of Forest Fragmentation on the Vertical Stratification of Neotropical Bats

Inês Silva,Fábio Z Farneda,Ricardo Rocha,Adrià López-Baucells,Christoph F J Meyer

doi:10.3390/d12020067

Abstract

Vertical stratification is a key component of the biological complexity of rainforests. Understanding community- and species-level responses to disturbance across forest strata is paramount for evidence-based conservation and management. However, even for bats, known to extensively explore multiple layers of the complex three-dimensional forest space, studies are biased towards understory-based surveys and only few assessments of vertical stratification were done in fragmented landscapes. Using both ground and canopy mist-nets, we investigated how the vertical structure of bat assemblages is influenced by forest fragmentation in the experimentally fragmented landscape of the Biological Dynamics of Forest Fragments Project, Central Amazon, Brazil. Over a three year-period, we captured 3077 individuals of 46 species in continuous forest (CF) and in 1, 10 and 100 ha forest fragments. In both CF and forest fragments, the upper forest strata sustained more diverse bat assemblages than the equivalent understory layer, and the midstory layers had significantly higher bat abundance in fragments than in CF. Artibeus lituratus and Rhinophylla pumilio exhibited significant shifts in their vertical stratification patterns between CF and fragments (e.g., R. pumilio was more associated with the upper strata in fragments than in CF). Altogether, our study suggests that fragmentation modulates the vertical stratification of bat assemblages.

Highlights

Tropical forests harbor ca. 60% of all known animal and plant species in only 8% of the planet’s surface [1]
With standardized abundance, the best model revealed a significant interaction between stratum and habitat (CF versus fragments), we could not disentangle the effect of fragment size: both upper and lower midstory layers had significantly higher bat abundance in fragments, while the subcanopy had significantly higher abundance in continuous forest (CF) sites (Table S4)
By simultaneously sampling in the understory, midstory and subcanopy of CF and forest fragments we show that fragmentation modulates the vertical stratification of bat assemblages in the Biological Dynamics of Forest Fragments Project (BDFFP)

Summary

Introduction

Tropical forests harbor ca. 60% of all known animal and plant species in only 8% of the planet’s surface [1]. 60% of all known animal and plant species in only 8% of the planet’s surface [1] This diversity is largely mediated by the complex stratification and multidimensionality of tropical forest canopies, which allow for additional niche space and facilitate the coexistence of a large number of species in the same geographical area [2,3,4]. Biological assessments across the tropics tend to be largely limited to understory-level surveys that under-represent species associated with higher forest strata [5]. While these have provided important insights into the responses. Due to multiple and often interacting stressors, the region is facing rapid environmental change and since 1970 has lost over 790,000 km (nearly 20%)

Methods

Results

Discussion

Conclusion