Effects of changes in plant species richness and community traits on carabid assemblages and feeding guilds

Abstract

Experiments were conducted between 2001 and 2003 in constructed plant communities that were set up in 1996 on abandoned agricultural land. The primary aim of the experiment was to study how different secondary vegetation succession scenarios influence community development of invertebrates in different trophic levels. The succession scenarios were obtained by sowing high diversity or low diversity seed mixtures of mid-successional plant species in 1996 in comparison with unsown plots where agriculture ceased in 1996 or 1999. Carnivorous carabid species generally preferred plots characterized by open vegetation, whereas herbivorous carabids generally favored plots associated with high plant diversity. However, carabid community composition was affected most by sampling year and there was also a dramatic shift over the three years in the relative proportion of the different trophic groups. Irrespective of treatment, the proportion of carnivores in the community declined with time, whereas phytophages increased over the course of the three years. By contrast, the proportion of omnivores peaked during the second year. These long-term changes were, at least to some extent, related to short-term changes in the structure and composition of the plant communities. The importance of local variation and temporal changes in plant species richness on carabids and other insect fauna are discussed.