Effects of Conversion to Organic Farming on Carabid Beetles (Carabidae) in Experimental Fields in the Czech Republic

Abstract

ABSTRACT The effects of conventional and organic farming and landscape structural elements on carabid beetles were compared in four experimental plots over a five-year crop rotation period. The working hypothesis was that the distance from ecotone as well as different types of farming are the main ecological factors influencing both the qualitative and quantitative features of carabid communities and their distribution. The question was whether or not there are changes in carabid communities in the fields with organic management in the first years of experiment. An attempt was made to detect such changes by two methods: using cenological indices and/or using ordinance methods (RDA). During the five-year study, 22498 specimens representing 91 carabid species were collected, with the following five species dominating: Poecilus cupreus, Pseudophonus rufipes, Anchomenus dorsalis, Pterostichus melanarius and Bembidion lampros. The methods of multidimensional statistical analysis used in the study (RDA) distinguished species composition according to their preference for ecotone, field margin or field centre. Consequently, the analysis detected the increasing ability of organic management to influence carabid communities, and finally it confirmed significant differences in the structure of carabid communities in organically and conventionally managed fields in the last year of the experiment. The preference of larger carabid species (Carabus granulatus, Carabus scheidleri) for organically managed fields was noted.