Efectos de la estructura del paisaje y de la vegetación en la diversidad de murciélagos filostómidos (Chiroptera: Phyllostomidae) de Oaxaca, México

Abstract

Effects of landscape and vegetation structure on the diversity of phyllostomid bats (Chiroptera: Phyllostomidae) in Oaxaca, Mexico. The tropical forest fragmentation is known to affect the spatial structure of the landscape and habitat. These alterations can modify the attributes of bat assemblages, however, this phenomenon has been little studied and understood. In this work we evaluated the structure of landscape (i.e. composition and configuration) and vegetation, and its relationship with assemblage-and population-level characteristics of phyllostomid bats in a tropical rainforest of Southeastern Mexico. For this, we previously selected 12 sites located in continuous and fragmented forests, where bats were captured using mist nets during a two years sampling effort (144 nights). Bats relative abundance, species richness (diversity of order 0, 0 D), Shannon diversity index ( 1 D) and Simpson index ( 2 D) were evaluated in all sites, and their relationship with seven measures of landscape structure and seven measures of vegetation structure was described using a Hierarchical Partitioning Analysis. A total of 1 840 individuals of 29 species of phyllostomid bats were captured in this period. Differences in the assemblages were manifested only in the relative abundance and not in the richness of the species. The assemblages of fragmented forest exhibited greater variation in species composition and a greater abundance of frugivorous and nectarivorous bats in comparison with the assemblages of continuous forest. The landscape configuration was related to the assemblage-and population-level attributes, contrasting with previous studies where the composition was a key element. At habitat level, tree density and canopy cover determined the abundance of bats. Nectarivorous and frugivorous bats were mostly found in disturbed vegetation landscapes, primarily due to landscape configuration (e.g. edge density). This phenomenon could be a response to the availability of food in primary and intermediate successional stages, which are characterized by an abundance of food value. Rev. Biol. Trop. 62 (1): 217-239. Epub 2014 March 01.

Ecological Traits of Phyllostomid Bats Associated with Sensitivity to Tropical Forest Fragmentation in Los Chimalapas, Mexico

“…We then carried out a supervised classification on the resulting map, generating two categories: continuous vegetation areas and areas without apparent vegetation. We chose this dichotomous classification as we were unable to distinguish categories of vegetation reliably [29]. Upon this classification, 33 potential circular areas were delimited, each with a 4 km diameter.…”

“…We captured 1,840 individuals from 29 phyllostomid bat species, of which 747 (25 species) were captured in CF and 1,093 (25 species) in FF area. The completeness of inventories was adequate (CF > 78.4%, FF > 77.1%), based on estimates of expected number of species obtained through the first-order jacknife estimator [29]. For purposes of this study, only 20 species were selected and nine species were excluded.…”

“…The study area is a fragmented landscape in early stages of disturbance, with a predominance of continuous forest patches as well as large areas of induced grassland and itinerant farming [29]. The disturbances in the region are the result of forest fires, semi-intensive livestock, and extraction of timber trees [28].…”

“…The measures were obtained using FRAGSTAT v3.3 [34]. All areas were ordered using a Principal Component Analysis (PCA), allowing us to recognize two large groups: continuous forest (CF) and fragmented forest (FF) areas [29]. CF areas were characterized by a larger forest cover proportion (> 84.96%), low patch density (< 1.27 patches/100 ha), and lower edge density (< 38.59 m/ha); while FF areas showed low forest cover (< 75.87%), high patch density (> 2.46 patches/100 ha), and higher edge density (> 62.07 m/ha).…”

“…It is also important to promote the recovery of areas with secondary vegetation in advanced successional stages and the conservation of plant species that are the diet of several phyllostomid bats [7,77]. The application of these strategies is particularly important in our study area because Los Chimalapas is the last rainforest areas in Mexico with high biodiversity, which is under severe pressure from human activities [28,29]. Total Phyllostomidae Family C1 C2 C3 C4 C5 C6 F1 F2 F3 F4 F5 …”