Epsilon Archive for Student Projects

Abstract

Biodiversity plays an important role in sustainable food production, because of its contribution to several important ecosystem services, including biological control of pests by natural enemies. Predatory natural enemies, such as carabid beetles, have the potential to mitigate pest infestations and thereby improve crop yield and quality, as well as reduce the need for pesticides. However, field management, such as tillage, may affect carabid communities negatively, thereby reducing the effectiveness of the biological control. Additionally, anthropogenic climate change will lead to increased temperatures, and how this will affect the carabid communities, pest dynamics and ecosystem services is uncertain. Functional redundancy in the carabid communities can bolster the resilience of the ecosystem service by enhancing the likelihood of functional overlap, thus, ensuring the performance of a specific function, even if some species are lost or reduced. In this study, I assessed how functional redundancy and climate resilience of biological control as well as several carabid community metrics differ between two tilling systems: conservation tillage and ploughing. I also calculated the climate niches for six individual carabid species. Data were collected in 12 conventionally managed fields of winter wheat around Uppsala, Sweden, in June and July 2023.
The main results showed that conservation-tilled fields had a higher species evenness and a higher activity density of carnivorous species, while ploughed fields had a higher activity density of omnivorous species, a larger community mean body size and a higher functional redundancy and climate resilience. I suggest that the higher functional redundancy in ploughed fields was partially driven by the increased abundance of large-bodied carabids, which, by consuming more prey due to their higher metabolic requirements, will contribute more to functional redundancy and further improve resilience. However, the dominance of one single large-bodied species will reduce functional redundancy, since it depends on the functional overlap between multiple species. Therefore, there must be additional factors explaining the higher functional redundancy and climate resilience in ploughed fields, beyond the promotion of large body size, which was not determined in this study.