Agriculture, Ecosystems & Environment

Volume 200, 1 February 2015, Pages 219–234

Farmlands with smaller crop fields have higher within-field biodiversity

• Lenore Fahrig^{a, ,} ,
• Judith Girard^a, ,
• Dennis Duro^a, ,
• Jon Pasher^b, ,
• Adam Smith^b, ,
• Steve Javorek^c, ,
• Douglas King^a, ,
• Kathryn Freemark Lindsay^a, ,
• Scott Mitchell^a, ,
• Lutz Tischendorf^a,

doi:10.1016/j.agee.2014.11.018

Get rights and content

---

Highlights

•

Multi-landscape study of effects of farmland pattern on biodiversity in crop fields.

•

Seven taxa studied – birds, plants, butterflies, bees, syrphids, carabids and spiders.

•

Diversity and abundance of all taxa decline with increasing mean field size.

•

Field size effect is stronger than effect of area under cultivation.

---

Abstract

Simple rules for landscape management seem elusive because different species and species groups are associated with different land cover types; a change in landscape structure that increases diversity of one group may reduce diversity of another. On the other hand, if simple landscape–biodiversity relationships do exist despite this complexity, they would have great practical benefit to conservation management. With these considerations in mind, we tested for consistent relationships between landscape heterogeneity and biodiversity in farmland (the cropped areas in agricultural landscapes), with a view to developing simple rules for landscape management that could increase biodiversity within farmland. Our measures of farmland heterogeneity were crop diversity and mean crop field size, where increases in crop diversity and/or decreases in mean field size represent increasing landscape heterogeneity. We sampled the abundance, and alpha, gamma and beta diversity of birds, plants, butterflies, syrphids, bees, carabids and spiders, in crop fields within each of 93 1 km × 1 km agricultural landscapes. The landscapes were selected to represent three gradients in landscape composition and heterogeneity: proportion of the landscape in crop, mean crop field size and Shannon crop type diversity of the farmland. We found that mean crop field size had the strongest overall effect on biodiversity measures in crop fields, and this effect was consistently negative. Based on our results we suggest that, if biodiversity conservation in crop fields is a priority, policies and guidelines aimed at reducing crop field sizes should be considered.

Keywords

• Landscape heterogeneity;
• Landscape complexity;
• Landscape composition;
• Landscape configuration;
• Edge density;
• Agricultural intensification

Corresponding author. Tel.: +1 613 512 2600x3856.

Copyright © 2014 Elsevier B.V. All rights reserved.