Can landscape level semi-natural habitat compensate for pollinator biodiversity loss due to farmland consolidation?

Traditional farming landscapes in China consist of small irregular fields with an intimately interspersed semi-natural habitat network of field margins, but are increasingly converted into consolidated ones that consist of standardized fields with reduced areas of field margins and other semi-natural habitat. It is unclear how such farmland consolidation influences pollinator communities, and if there is a negative effect, whether this effect is mitigated by semi-natural habitat present in the wider landscape. We compared the diversity and abundance of wild pollinators in oilseed rape fields that were embedded in landscapes that consisted either of traditional or consolidated farmland. The landscapes spanned a range of semi-natural habitat area from 10% to 73% at a scale of one km radius in Jiangxi Province, China. Pollinators were sampled using pan traps during two years (2015 and 2019). Results showed that pollinator diversity was positively associated with the proportion of semi-natural habitat in both traditional and consolidated farming landscapes, but was higher in traditional farming landscapes. In both years, there was no difference in pollinator abundance between landscapes with traditional and consolidated fields. The results indicate that the network of field margins in traditional farmland supports a diverse pollinator community, and that land consolidation has equivalent effects on pollinator diversity as substantial decreases in semi-natural habitat in the wider landscape. The role of semi-natural habitat in supporting farmland biodiversity and its associated services needs therefore to be considered in plans for farmland consolidation.