Invertebrate diversity is shaped by farm management, edge effects and landscape context in the Prairie Pothole Region of Canada

Terrestrial invertebrates provide essential ecosystem services, and there is concern that their contribution could be compromised by population declines due to agricultural intensification, including pesticide use. Identifying alternative and beneficial agricultural land management measures could stem or reverse biodiversity loss. Here we examine morphospecies composition and abundance of terrestrial invertebrates sampled with pitfall traps and sweep nets in fields and field margins in the Prairie Pothole Region, Canada, close to focal wetlands on 43 sites representing four land management types. These were: conventional, minimum tillage, organic, and perennial cover. We estimate diversity at local and regional scales (alpha, beta, gamma) and examine the impacts of land management in interaction with landscape context on these descriptors of local and landscape biodiversity. We found that: 1) alpha morphospecies richness (hereafter ‘alpha richness’) was greater at conventionally-managed sites when they were surrounded by more grassland; 2) alpha richness differed among land management types for field locations, but not field margin locations (and also tended to be lower in fields than field margins, especially for sweep net samples); 3) species composition differed somewhat between sites managed for perennial cover versus the remaining three land management types; and 4) conventional sites had the lowest gamma evenness. Our results suggest that increasing the amount of grassland in landscapes could lessen the impact of conventional agriculture and that field margins in intensively managed farming systems are important for invertebrate diversity in this region. Maintaining natural and seminatural cover in agroecosystems, in addition to low-intensity farming practices, could sustain invertebrate biodiversity and facilitate important ecosystem services. •We compared arthropod diversity among land management types and landscape contexts.•At conventionally-managed sites, alpha richness increased with grassland amount.•Richness decreased with increasing management intensity in fields but not margins.•Increasing grassland amounts around conventional fields could benefit invertebrates.•Less intensive management and more semi-natural cover are better for invertebrates.