Temporary non-crop habitats within arable fields: the effects of field defects on carabid assemblages

SEIDL, MIROSLAV; GONZÁLEZ, EZEQUIEL; KADLEC, TOMÁS; SASKA, PAVEL; KNAPP, MICHAL

Fiera di Primiero

Conferencia; Carabids in extreme environments. 19th European Carabidologists Meeting; 2019

Landscape heterogeneity and complexity are commonly generally positively affect linked to biodiversity of in agroecosystems. Carabid beetles represent abundant and important predators of pests and weed seeds in temperate agroecosystems and their spatial distribution is significantlyare affected by landscape structure. Several studies have described the contribution of permanent non-crop habitats such as woodlots, hedgerows and grassy margins on carabid communities. However, temporal non-crop habitat islands within arable fields have been rarely investigated. The aim of this study was to investigate spatial distribution of carabid beetles within oilseed rape fields with temporary non-crop habitats (field defects). Field defects are areas where sown plants are poorly developed and often arise by sowing failures or in consequence ofdue to extreme local conditions (soil humidity, missing nutrients). In twenty oilseed fields, we studied carabid assemblages collected with pitfall traps in three habitat types (oilseed field interiors, field defects and boundaries between them) and in two sampling periods (spring and summer). Our results showed that both activity-density and species richness were lowest in field defects than in boundaries and field interiors in both sampling periods, Our results indicate indicating that field defects represent less favouritewere not a preferred habitat for carabids. Activity-density and species richness significantly increased from spring to summer in all habitat types. Species composition of carabid assemblages significantly differed between field defects and field interiors or boundaries, however rather than by a presence of unique carabid species were field defect assemblages characterised by overall low species richnesswhich is explained by the impoverished communities and the presence of few indicator species. Interestingly, field defects with well-developed weed plant cover hosted carabid assemblages with species richness comparable to field interiors, indicating that re-sowing of large field defects can support carabid populations within arable fields. However, consequences of re-sowing on other arthropod taxa, e.g., insects requiring habitats with bare ground, and on populations of rare weeds need to be evaluated. Missing The lack of effects of field defect size on carabid assemblages within field defects indicates that carabid beetles are able to identify even very small patches with unsuitable conditions, (e.g., very low humidity, high temperature or missing food sourcesscarcity), and can be successfully employed as bioindicators.