Composition and Richness of Arboreal ants in Fragments of Brazilian Caatinga: Effects of Secondary Succession

Abstract

Ecological succession is a complex processes involving changes in the structure of plant community and it is an important factor determining the structure of arboreal ants assemblages, but little is known about the effects of succession on ant assemblages in regions of Tropical Dry Forests (TDFs), such as the Brazilian Caatinga. The aim of this study was to investigate the effects of ecological succession on the richness and species composition of arboreal ants in fragments of Caatinga, testing the following hypothesis: i) the richness of arboreal ants increases along a gradient of forest succession, in response to tree richness and/or density; ii) species composition of arboreal ants differs among stages of forest succession due to differences in vegetation structure in theses stages. This study was conducted in 15 plots distributed in three areas with different stages of secondary succession (early, intermediate and late). Tree density and richness were used as surrogate of vegetation structure. Ants were sampled using the technique of beating the foliage and baited pitfall traps, where five trees were sampled per plot, totaling 75 individual trees sampled. We sampled 37 species of ants, distributed in 16 genera and five subfamilies. Ant richness differed among stages of succession and seasons, with higher number of species in the late succession and rainy period, also increasing with tree richness and density. Besides, there was a distinct composition of ant species among stages of succession and seasons. Results obtained in this study reinforce the importance of using ants as environmental bioindicators, since the sensitivity to environmental variations of this group enables us to differentiate early and late successional stages of forest succession in Caatinga environment.

Ant Assemblage Structure in a Secondary Tropical Dry Forest: The Role of Ecological Succession and Seasonality

“…While acknowledging that this provided an underestimate of wet season canopy cover, this measure was used as an estimate of the climatic conditions of the stratum, because canopy cover can affect the availability of light and humidity in the understory. Areas with greater canopy cover may maintain a microclimate that is more suitable for arboreal ant species (Sousa-Souto et al, 2016).…”

“…These factors can increase the area of TDFs undergoing ecological succession. In this scenario, vegetation and environment change mutually during secondary succession and in turn also affect biota, for example, by influencing resource availability and interactions among organisms (Sousa-Souto et al, 2016). According to Ribas et al (2002Ribas et al ( , 2003, competition is an important force that structures the ant assemblages which is regulated by habitat heterogeneity.…”

“…However, some studies agree with a limited role of competition between ant species and pointed that environmental constraints may be more important for ant assemblages (Baccaro et al, 2011;Jacquemin et al, 2016). Elucidating the pattern of variation in the ant assemblages along the succession and to identify environmental variables that explain this variation consists of subjects which have been poorly documented (Sousa-Souto et al, 2016).…”

Ant diversity in Brazilian tropical dry forests across multiple vegetation domains

“…competition, mutualism), resource availability, and environmental variables are often described as the major drivers of ant community structure (Srivastava 1999, Baccaro et al 2012, Camarota et al 2016. Examples of environmental variables include tree richness, height, and abundance (Ribas et al 2003, Klimes et al 2012, Sousa-Souto et al 2016, variation in canopy coverage (Neves et al 2013), and characteristics of soil structure (Schmidt et al 2013). At larger spatial scales, historical processes of community assembly, landscape configuration and variation in temperature and precipitation (both current and historical) are seen as key factors shaping ant communities (Dunn et al 2009, Jenkins et al 2011, Solar et al 2016.…”

“…Most studies of ant diversity in TDFs seek to understand the mechanisms that determine local community structure (e.g. Gove et al 2005, Delsinne et al 2007, Zelikova and Breed 2008, Neves et al 2010, Neves et al 2013, Sousa-Souto et al 2016, with few studies examining larger spatial scales (but see Delsinne et al 2010, Silvestre et al 2012, and Marques and Schoereder 2014. High plant richness and density, which are good proxies for habitat heterogeneity (Ribas et al 2003, Neves et al 2014, Leal et al 2016, likely influence insect communities since more heterogeneous habitats have been assumed to provide greater resource availability and variety (Stein et al 2014, Leal et al 2016.…”