Effects of vegetation structure and edge proximity on insect distribution in an arboreal Caatinga area in Brazil

Abstract

Caatinga is a very important and neglected dry tropical forest biome of Brazil. Recent evidence indicates that anthropogenic threats to Caatinga have grown in recent years, and there are still gaps in the knowledge of how these effects alter biodiversity. In the present study, we evaluated the effects of vegetation structure and edge proximity on the distribution of bioindicator insects (galling insects and ants) in an arboreal Caatinga area under the influence of a monoculture in Brazil. We recorded a total of 10 species and 2,131 specimens of ants and 11 species and 29 individuals of galling insects. Species richness, abundance, and composition of galling insects and ants did not differ between edge and interior plots of the forest. Ant diversity was also not affected by the structural parameters of vegetation (plant abundance, vegetation cover, and vegetation height). On the other hand, the plant abundance positively influenced the richness and the abundance of galling insects in the plots. Our findings suggest that the distribution of ants and galling insects in Caatinga forest edge and interior environments did not differs likely due the opening of the canopy gives the arboreal Caatinga relatively homogeneous climatic characteristics throughout the forest. Already the structure of vegetation positively influences galling insects due to the high degree of dependence that endophagous life-form generates on these insects. Our results show that despite similar responses to the edge effect, ants and galling insects respond differently to vegetation structure, indicating that the structuring of these insect communities is guild-dependent.

Habitat quality and edge area of fragments determine insect diversity in a heavily used landscape: Implications for forest landscape restoration

“…However, several studies suggest that some smaller and isolated forest fragments indeed harbor higher species diversity (Golden & Crist, 2000; Su et al, 2015; Volenec & Dobson, 2020). This is due to the nature of the surrounding habitats (e.g., agricultural fields and human habitations), which act as a source pool for generalists species and thereby contribute to the ecotones of the forest fragments (Cosma, 2016; Oliveira et al, 2020; Ribas et al, 2005). Therefore, heterogeneous landscapes often disprove the theory of island biogeography (Cook et al, 2002; Kupfer et al, 2006).…”