Butterfly responses to cultivated field abandonment are related with ecological traits in a temperate Japanese agricultural landscape

To examine the effects of cultivated field abandonment on butterfly assemblages, we investigated butterfly assemblages in seven local settlements with varying degrees of abandonment of cultivated fields. We hypothesized that species with specialist characteristics (univoltine and oligophagous species) would increase with an increasing proportion of old abandoned fields (50-80% of these fields had been abandoned for approximately 30 years) and that species that utilized annual plants would increase with an increasing proportion of recently abandoned fields (abandoned for one to two years). Species richness and the abundance of univoltine, oligophagous, and non-annual feeding species increased with increasing proportions of old abandoned fields, whereas those of multivoltine, polyphagous, and annual feeding species decreased or remain stable. Species that utilized annual plants did not respond to the amount of recently abandoned fields. Redundancy analyses showed that the proportions of old and recently abandoned fields affected butterfly assemblages but that other uncontrolled factors, such as road density and the distance to the continuous forests, did not affect butterfly assemblages. Our results showed that abandoned cultivated fields are beneficial to some specialist butterflies that are sensitive to the simplification of landscapes and can be an option for increasing biodiversity, particularly in simplified agricultural landscapes. Further research is required to reveal factors affecting vegetation types in abandoned cultivated fields, to determine the relative effects of local compared with landscape factors regulating butterfly assemblages, and to examine the role of abandoned cultivated fields compared with other semi-natural vegetation for conserving biodiversity in agricultural landscapes.