Using ants to manage sustainable grazing: Dynamics of ant faunas along sheep grazing gradients conform to four global patterns

Abstract

Ants are considered an important faunal group for the functioning of arid rangelands, they have a long history of use for environmental monitoring, and exhibit four global patterns in grazing lands: (i) soil and vegetation type are primary determinants of ant community composition, and have a far greater effect on ant community composition than grazing; (ii) grazing induces species compositional change, but does not necessarily affect species richness or abundance; (iii) a species response to grazing is not necessarily consistent across habitats; and (iv) approximately one-quarter to one-half of species that are common enough for statistical analysis have significant responses to grazing. Here we report the patterns of arid zone ant faunas as they exist after several decades of sheep grazing in southern Australia, and examine the extent to which they conform to the four global patterns. We measured ant faunas along grazing gradients (varying distance to water) in seven paddocks containing two soil and two vegetation types on five pastoral properties.Total site abundance and richness of ants did not differ significantly with distance from water, but the abundance of 10 (34%) of the 29 most common species did differ; three were increasers, three were decreasers, and four had mixed responses dependent on soil/vegetation type. Rare species showed no trend with grazing intensity. The ant fauna of the more structurally complex vegetation types appeared to be the most vulnerable to grazing effects. Multivariate analysis showed soil type was the primary factor influencing ant faunal composition, followed by vegetation structure; however, grazing treatment effects were present. This study fully supports the recently identified global patterns of ant responses to grazing. It also shows that sampling regional ant faunas using widely dispersed traps can detect ant faunal patterns comparable to studies that use smaller-scale grids of traps.

Ant diversity and bio-indicators in land management of lac insect agroecosystem in Southwestern China

“…Ants have a long and successful history as a bioindicator taxon (Andersen et al 2002Andersen and Majer 2004;Andersen and Sparling 1997;King et al 1998;Lobry de Bruyn 1999;Majer 1983;Hoffmann and Andersen 2003;Hoffmann 2010;Hoffmann and James 2011). The interpretation of ant responses to environmental change have largely occurred at the community-level, leaving one of the greatest challenges for the use of ants as bioindicators being the interpretation of (often seemingly idiosynchratic) species-level responses (Hoffmann 2010).…”

“…Of the many taxa often utilised as bioindicator surrogates for all biota, ants have a long and proven record track record for providing results that are ecologically interpretable (Majer 1983;Greenslade and Greenslade 1984;Andersen 1990;Alonso 2000;Kaspari and Majer 2000;Hoffmann and Andersen 2003;Hoffmann 2010;Hoffmann and James 2011). Ants merit monitoring based on their inherent ecological qualities, independent of any ''indicator'' attributes they might have (Underwood and Fisher 2006), and strong positive correlations between ant species richness and that of other taxa (Alonso 2000).…”

Ant community structure and response to disturbances on coastal dunes of Gulf of Mexico

“…Vegetation structure alters food resources, nesting sites, and micro-climate conditions (Boomsma and Devries 1980;Rico-Gray et al 1998;Andersen et al 2006;Hoffmann and James 2011), and further regulates ant diversity, behavior, and interactions among species (Huxley and Cutler 1991; Botes et al 2006;Wilkinson and Feener 2007;Hill et al 2008). The general assumption is that species diversity is positively associated with vegetation complexity (Bonte et al 2002;Tews et al 2004;Sarty et al 2006).…”

Effects of grassland management practices on ant functional groups in central North America

“…Differences in ant foraging practices and social dominance permit the classification of ants into different functional groups (Andersen 1997). Compared to traditional measures such as species richness and total ant abundance, ant functional groups respond more consistently to disturbance (Stephens andWagner 2006, Hoffmann andJames 2011).…”