Assessing tillage disturbance on assemblages of ground beetles (Coleoptera: Carabidae) by using a range of ecological indices

Many ecological studies have used diversity indices to assess the impact of environmental disturbance. In particular, ground beetles have been advocated as a good group for assessing disturbance. Most studies on various organisms have used only one or two indices. For our study of the impact of tillage disturbance on carabid beetles in farm fields in southern Ontario, Canada, we used seven different diversity indices (richness, Shannon-Wiener, Berger-Parker, Q-statistic, Margalef, alpha and evenness). Few studies have used deviation from diversity abundance models as a measure of disturbance; however, we use three that are applicable to our data ( geometric, log-normal and log-series). The indices and models were used to test the null hypothesis that there is no change in diversity with increasing tillage disturbance, and that there is no difference in diversity with different crops or years. We were not able to reject the null hypothesis that there is any diversity difference among farms. We also found that there was no single diversity index or model that was better than any other at detecting disturbance. These results are supplemented by a meta-analysis of 45 published data sets for the same taxon but in different habitats. The meta-analysis supports the conclusions from our field research that diversity indices and models are not useful for detecting the possible effect of disturbance on assemblages of carabid beetles.