BayCEER Workshop 2016

Ant community changes under increasing land-use in temperate grassland

O 4.2 in Land-use effects on ecosystems

13.10.2016, 12:15-12:30, H36, NW III

Introduction

Ants are an important functional group of temperate grassland ecosystems. Land-use intensification has been shown to have a negative influence on ant diversity. However the mechanisms leading to these effects are not well understood and may affect different ant species differently, as ant species may differ in trophic niche. Predatory ant species or those with a broader nutritional niche are less affected as prey items are still available in intensively used plots while trophobionts strongly decrease, potentially limiting the availability of carbohydrates.

Material and Methods

To investigate the changes in ant communities, we sampled ants in 140 temperate grassland plots (50x50m) in three regions in Germany within the Biodiversity Exploratories using pitfall traps (12 pitfall traps per plot) and hand-sampling. The grasslands are used as meadows or pastures at different intensities.

Results

We found that ant species richness decreased significantly with increasing land-use. This was not only the result of losing particular ant species, but also resulted from a turnover in occurring species. As a consequence, functional diversity of ant communities decreased significantly with larger and subterranean species being absent at higher land-use intensity. Apart from the decreasing number of species we also found a reduced colony density and smaller nest-mound sizes with higher land-use intensity. 

Conclusions

This indicates that some grassland ant species seem to be less affected by land-use intensification, which might relate to the trophic niche of the ant species in question. To determine the niche we are conducting stable isotope analysis for the ant species present over the land-use intensity gradient.

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