The Use of Ants and Other Soil and Litter Arthropods as Bio-Indicators of the Impacts of Rainforest Clearing and Subsequent Land Use

Background

This study evaluates the impacts of rainforest clearing on soil and litter arthropods with a particular focus on ant species.

Research Goals & Methods

The study area was located on the Maleny Plateau in Eastern Australia, which consists primarily of subtropical rainforest and lands that have been cleared for pasturing livestock. Twenty four study sites were selected within 13 km of Maleny town, 12 plots in forested areas and 12 in pastureland. Forests sites were notophyll vine forests or notophyll feather palm vine forests, while 10 out of the 12 pasture sites were extensively grazed by horses or cattle. At each site, arthropods were collected using pitfall traps and soil and litter extraction methods at regularly spaced sampling points along a transect. Extraction was preformed in three circular plots 3m in diameter, and arthropods collected from the litter and soil using a 40 W clear lightbul. Twelve pitfall traps filled with ethanol were placed along each transect as well. All forest sampling plots were located at least 22m away from the forest edge, and all pastureland sampling sites were located at least 100m away from forest fragments.

Conclusions & Takeaways

Upon analysis, the data collected showed that very different species of arthropods live in rainforests than in pastureland, and the results extended down to a fine resolution. This effect was clearest in ant species, but was also obvious when looking just at arthrodpod diversity. This shows that using specific taxa is not necessarily more effective than using broader measures of arthropod diversity as measurements of ecosystem health and functioning. The authors discuss the problem with using ant species diveristy as a measure of ecosystem health; that is, because many species are habitat specialists, the data can be spatially skewed. The authors recommend using a composite index of arthropod diversity in place of one based on species diversity of a specific order. This also reduces reliance on one or a small number of individual species as indictors.