Using insect diversity for determining land restoration development: Examining the influence of grazing history on ant assemblages in rehabilitated pasture

Ant assemblages, used widely as bioindicators of land management practices, were sampled in rehabilitated pastures and surrounding habitats at Norwich Park Coal Mine in central Queensland, Australia. As the end-use goal of a number of rehabilitated mine sites in the region is sustainable pasture-land, the aim of this study was to investigate the influence of varying grazing histories on ant fauna, to provide further understanding on the function of rehabilitated agroecosystems and multi-trophic interactions. Examination of seven study sites revealed three distinct ant assemblages, broadly reflecting mining and grazing history. Rehabilitated pastures where grazing had ceased 2 years prior to ant sampling contained low species richness with a basic ant composition, regardless of stocking rate, and was similar to ungrazed rehabilitated pasture. The rehabilitated pasture with continual low intensity grazing showed ant compositional similarities to the neighboring unmined pasture, although assemblage descriptors were intermediate between unmined and rehabilitated sites. Buffel grass (Pennisetum ciliare, basionym Cenchrus ciliaris) and other stoloniferous or rhizomatous grasses were the principal influence on ant assemblages, with grazing reducing the ground dominance of such grasses and providing a more favorable habitat for a wider range of ant species.

► Ant assemblages on rehabilitated pasture were examined.
► Buffel grass cover significantly influenced ant assemblages.
► Continuous grazing reduced buffel grass cover.
► Ant species richness was lowest where buffel grass cover was most dominant.
► Ant composition most resembled ‘natural’ pasture where buffel grass was suppressed.