Differing effects of fallow type and landscape structure on the occurrence of plants, pollinators and birds on environmental fallows in Finland

Abstract

Long-term grassland fallow and short-term meadow fallow represent alternative fallowing strategies for biodiversity conservation on farmland. Conventional grassland mixtures are used to establish long-term grassland fallows, whereas short-term meadow fallows are sown with specific meadow seed mixtures and require regular re-establishment to maintain the abundance of sown species. This study examined the impact of fallow type and landscape structure on the species richness and abundance of four taxa: plants, bumblebees, butterflies and birds. Long-term grassland fallows and short-term meadow fallows were studied in four contrasting landscape types in Finland, differing in the cover of forest and perennial grasslands. The fallow type and landscape structure affected each species group differently, and the value of a particular fallow type was also modified by landscape setting. Bumblebees were most abundant in short-term meadow fallows, whereas butterflies benefited more from long-term grassland fallows. Species richness of plants and butterflies were higher in forested than in open landscapes. Long-term grassland fallows promoted species richness of butterflies as well as the abundance of foraging edge birds in forested landscapes, whereas short-term meadow fallows enhanced the abundance of foraging edge birds in open landscapes. In landscapes with high grassland cover, the breeding density of open farmland birds was higher in meadow fallows than in grassland fallows, while the reverse was true in landscapes with low perennial grassland cover. The fallowing strategy thus can be adapted to the landscape context depending on the specific objectives. For overall biodiversity enhancement, establishing and managing different kinds of fallows is important.