Agricultural matrices affect ground ant assemblage composition inside forest fragments

Abstract

The establishment of agricultural matrices generally involves deforestation, which leads to fragmentation of the remaining forest. This fragmentation can affect forest dynamics both positively and negatively. Since most animal species are affected, certain groups can be used to measure the impact of such fragmentation. This study aimed to measure the impacts of agricultural crops (matrices) on ant communities of adjacent lower montane Atlantic rainforest fragments. We sampled nine forest fragments at locations surrounded by different agricultural matrices, namely: coffee (3 replicates); sugarcane (3); and pasture (3). At each site we installed pitfall traps along a 500 m transect from the interior of the matrix to the interior of the fragment (20 pitfall traps ~25 m apart). Each transect was partitioned into four categories: interior of the matrix; edge of the matrix; edge of the fragment; and interior of the fragment. For each sample site, we measured ant species richness and ant community composition within each transect category. Ant richness and composition differed between fragments and matrices. Each sample location had a specific composition of ants, probably because of the influence of the nature and management of the agricultural matrices. Species composition in the coffee matrix had the highest similarity to its corresponding fragment. The variability in species composition within forest fragments surrounded by pasture was greatest when compared with forest fragments surrounded by sugarcane or, to a lesser extent, coffee. Functional guild composition differed between locations, but the most representative guild was ‘generalist’ both in the agricultural matrices and forest fragments. Our results are important for understanding how agricultural matrices act on ant communities, and also, how these isolated forest fragments could act as an island of biodiversity in an ‘ocean of crops’.

Proportion of Grassland at Landscape Scale Drives Natural Pest Control Services in Agricultural Landscapes

“…Among seed predators, small mammals, ants and carabids have dispersal capacities ranging from 500 to 750 m (Wegner and Merriam, 1990;Holland et al, 2004;Zumeaga et al, 2021). Moreover, small mammals, ants and carabids can benefit from grasslands (Fischer and Schröder, 2014;Petit et al, 2017;Assis et al, 2018) as well as forest patches (Wegner and Merriam, 1990;Holland and Fahrig, 2000;Assis et al, 2018) to maintain their population and may explain why seed predation rates increase with forest proportion. For aphids, spiders and carabids are natural enemies with dispersal capacities that match the 500 -750 m spatial extent (Holland et al, 2004;Maes et al, 2014) and appear as potential candidates involved in aphid predation rates here.…”

Effects of Habitat Conversion on Ant Functional Groups: A Global Review

“…The response of predators and cryptic species to conversion may be due to their specificities to their own habitat conditions and high specialization of requirements, being especially sensitive to disturbances (Andersen & Majer, 2004;Underwood & Fisher, 2006;Kone et al, 2012). This could also be the case of subordinate Camponotini, which also tend to occur in complex, heterogeneous and shaded habitats with abundant leaf litter for nesting and foraging (Andersen, 1997;Hoffmann & Andersen, 2003;Hill et al, 2008;Parui et al, 2015;Assis et al, 2018).…”

“…Army ants, in turn, are harmed in highly disturbed habitats (Matsumoto et al, 2009) by the lack of adequate bivouac sites, unfavorable microclimate and few organisms living in leaf litter and fallen logs (Roberts et al, 2000;Peters et al, 2011). However, the active search for preys associated with the nomadic behavior (Gotwald, 1995), the environmental tolerance and broader diet of some army ant species, may allow the occurrence of this FG in anthropic environments (Perfecto, 1992;Roberts et al, 2000;Delabie et al, 2007;O'Donnell et al, 2007;Matsumoto et al, 2009;Schleuning et al, 2011;Assis et al, 2018). Cryptic species are more diverse and abundant in forest habitats, associated with tree cover (Majer et al, 2004;Dalle Laste et al, 2019), and in our study they were negatively affected by the conversion of habitat except in the tropical zone.…”

“…Species classification into FGs can be either a priori, according to a classification based on species characteristics or similarities, or a posteriori, with multivariate analysis techniques (Petchey, 2004;Calaca & Grelle, 2016). The classification into FGs has been widely used in recent studies of biotic communities, including ants (Hymenoptera: Formicidae) (Andersen, 1995; King et al, 1998;Delabie et al, 2000;Ottonetti et al, 2006;Underwood & Fisher 2006;Crist, 2009, Leal et al, 2012Lawes et al, 2017;Assis et al, 2018). Such groupings are based on taxonomic affinities, morphological patterns, and niche dimensions such as diet, nest location, foraging behavior, and habitat preference or environmental tolerance (Andersen, 1990(Andersen, , 1995(Andersen, , 1997Hoffmann & Andersen, 2003;Silvestre et al, 2003;Andersen & Majer, 2004;Weiser & Kaspari, 2006;Silva & Brandão, 2010;Brandão et al, 2012;Koch et al, 2019).…”

“…In general, habitat disturbance and conversion affect ant communities directly, by reducing the availability of resources and removing colonies, and indirectly, through changes in habitat structure, nesting site availability, temperature, and humidity (Andersen, 2000;Philpott et al, 2010). In addition, habitat changes promoted by agriculture, logging, grazing, mining, etc., may lead to the exclusion of sensitive groups and the advent of groups tolerant to disturbances, which can replace or compete with those present before the disturbance (Andersen, 1995(Andersen, , 2000Hoffmann & Andersen, 2003;Andersen & Majer, 2004;Ottonetti et al, 2006;Crist, 2009;Leal et al, 2012;Parui et al, 2015;Assis et al, 2018;Amaral et al, 2019). Highly specialized FGs, such as cryptic species, tend to be sensitive to changes in habitat due to their preference for forested environments and nesting and foraging in soil and litter (Hoffmann & Andersen, 2003).…”