Remnants of Native Vegetation Surrounding Do Not Affect the Diversity and Density of Birds in Brazilian Grassland-Restoration Sites

Thaiane Weinert Da Silva,Carla Suertegaray Fontana

doi:10.3389/fevo.2020.576705

Thaiane Weinert Da Silva, Carla Suertegaray Fontana

Open Access

https://doi.org/10.3389/fevo.2020.576705

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Abstract

Since in general the surrounding landscape influences the species diversity and abundance in fragments of native vegetation, an amount of native-vegetation cover nearby may also positively affect communities in restored areas, regardless of the sizes of individual habitat patches. We investigated for the first time whether the species richness, total abundance, and density of grassland birds in restoration sites are influenced by the amount of native grassland in the surrounding landscape in the Brazilian Pampa. We sampled birds by point counts in five restoration sites in the most representative area of grasslands in Brazil. We established an outer buffer zone with a 1 km-radius around the point-count areas in each site, and calculated the percentage of native grassland vegetation in the surrounding landscape. Bird species richness and abundance did not show a significant response to the amount of neighboring native grassland in restored areas. Individual analyses of the density of seven bird species associated to grassland also showed similar pattern. We believe the vegetation structure in these restoration sites may already been sufficiently re-established to provide necessary resources and a suitable habitat for the birds. Even so, we assume that previously existing landscape features were important for recovery of the vegetation structure, as continuous native grassland in the surroundings. Thus, we recommend consider the landscape context as an additional issue in studies dealing with conservation strategies for recovery of grasslands in Brazil.

Highlights

Global biodiversity has been continually impacted, with most species living in fragmented patches resulting from land-use changes and habitat destruction (Haddad et al, 2015; Fletcher et al, 2018)
We found no significant difference among the species richness (HLM, t-value = 3.22, P = 0.06) and abundance (HLM, t-value = 2.20, P = 0.13) of grassland birds and the amount of native habitat in the landscape (Figure 1)
The surrounding landscape matrix influences the responses of species in habitat fragments (Pretelli et al, 2018), and responses to landscape attributes provide information about improvements in habitat management (Kroll et al, 2014)

Summary

Introduction

Global biodiversity has been continually impacted, with most species living in fragmented patches resulting from land-use changes and habitat destruction (Haddad et al, 2015; Fletcher et al, 2018). The surrounding landscape influences the species abundance and diversity in fragments, since the landscape may include connecting corridors, influence dispersal between habitat fragments, and depending on the nature of land use, can alter conditions in habitat patches negatively or positively (Öckinger et al, 2012). Species richness can be shaped by the physical environment, which includes several characteristics of habitat patch area, e.g., quality, size, configuration, and connectivity (Aggemyr et al, 2018). In the case of birds, where individuals can occur across a variety of habitat patches (Whitaker and Warkentin, 2010; Lee and Carroll, 2014), the proportion of native-grassland patches remaining in the landscape can affect the presence of bird species in grasslands (Cerezo et al, 2011). Bird species distribution and occurrence can be strongly influenced by landscape characteristics (Lee and Carroll, 2014)

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