Farmland biodiversity: wildflower-sown islands within arable fields and grassy field margins both promote spider diversity

Tamara Rischen,Katharina Geisbüsch,Daniel Ruppert,Klaus Fischer

doi:10.1007/s10841-021-00363-2

Tamara Rischen, Katharina Geisbüsch + Show 2 more

Open Access

https://doi.org/10.1007/s10841-021-00363-2

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Abstract

Agricultural intensification and the concomitant landscape homogenization is leading to a worldwide decline in farmland biodiversity. Non-crop habitats in agroecosystems may counteract the loss of arthropods such as spiders and thus contribute to sustainable agriculture. However, the effectiveness of field margins and set-aside wildflower-sown patches in maintaining spider diversity is not well understood. Here, we investigated the effects of three different non-crop habitats, namely field margins, set-aside wildflower-sown patches under power poles (‘power pole islands’), and grassland fallows on spider diversity as compared to wheat fields in an agricultural landscape in western Germany. Using pitfall trapping and suction sampling, we show that species richness and overall conservation value were higher in non-crop habitats than in wheat fields. Interestingly, field margins and power pole islands differed from long-term grassland fallows only in conservation value, which was significantly higher in grassland fallows. Species assemblages differed considerably between grassland fallows, field margins and power pole islands, and wheat fields, documenting the added value of using different conservation strategies.Implications for insect conservationSmall-scale non-crop habitats adjacent to wheat fields were surprisingly effective in promoting spider diversity in an agricultural landscape, with field margins and power pole islands being equally effective. To maximize overall diversity in agricultural landscapes, we propose a combination of larger long-term fallows and smaller non-crop habitats such as field margins or set-aside wildflower-sown patches.

Highlights

Though agriculture is essential for providing food and other resources to an ever-growing human population, intensification of land use is considered to be one of the main causes of global biodiversity loss (Donald et al 2001; Benton et al 2002; Seibold et al 2019)
Pitfall trapping yielded 4407 spiders belonging to 91 species, and suction sampling yielded 535 spiders belonging to 63 species (Table A2, Supplementary Material)
Of the 112 spider species captured, 49 species were exclusively caught by pitfall trapping, 21 exclusively by suction sampling, and 42 species by both methods, with patterns being roughly similar across habitat types (Fig. A1, Supplementary Material)

Summary

Introduction

Though agriculture is essential for providing food and other resources to an ever-growing human population, intensification of land use is considered to be one of the main causes of global biodiversity loss (Donald et al 2001; Benton et al 2002; Seibold et al 2019). Intensively used crop fields are unsuitable for many organisms, and agricultural intensification comprises a major driver of biodiversity loss in industrialized countries (Donald et al 2001; Kleijn et al 2009). To counteract the widespread decline of biodiversity in agricultural landscapes, a wide variety of measures has been applied in recent decades, some of which aim to increase landscape heterogeneity, an important driver of species richness (Benton et al 2003; Fahrig et al 2011). Heterogeneous landscapes, composed of arable fields and adjacent non-crop habitats, may offer essential features such as hibernation and feeding places, refuges, and dispersal corridors

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