Increasing crop heterogeneity enhances multitrophic diversity across agricultural regions

Abstract

Agricultural landscape homogenization has detrimental effects on biodiversity and key ecosystem services. Increasing agricultural landscape heterogeneity by increasing seminatural cover can help to mitigate biodiversity loss. However, the amount of seminatural cover is generally low and difficult to increase in many intensively managed agricultural landscapes. We hypothesized that increasing the heterogeneity of the crop mosaic itself (hereafter "crop hetero-geneity") can also have positive effects on biodiversity. In 8 contrasting regions of Europe and North America, we selected 435 landscapes along independent gradients of crop diversity and mean field size. Within each landscape, we selected 3 sampling sites in 1, 2, or 3 crop types. We sampled 7 taxa (plants, bees, butterflies, hoverflies, carabids, spiders, and birds) and calculated a synthetic index of multitrophic diversity at the landscape level. Increasing crop heterogeneity was more beneficial for multitrophic diversity than increasing seminatural cover. For instance, the effect of decreasing mean field size from 5 to 2.8 ha was as strong as the effect of increasing seminatural cover from 0.5 to 11%. Decreasing mean field size benefited multitrophic diversity even in the absence of seminatural vegetation between fields. Increasing the number of crop types sampled had a positive effect on landscape-level multitrophic diversity. However, the effect of increasing crop diversity in the landscape surrounding fields sampled depended on the amount of seminatural cover. Our study provides large-scale, multitrophic, cross-regional evidence that increasing crop heterogeneity can be an effective way to increase biodiversity in agricultural landscapes without taking land out of agricultural production.

Keywords

multitaxa; biodiversity; crop mosaic; farmland; landscape complementation

Published in

Proceedings of the National Academy of Sciences of the United States of America
2019, Volume: 116, number: 33, pages: 16442-16447

SLU Authors

• Henckel, Laura

  • SLU Swedish Species Information Centre, Swedish University of Agricultural Sciences
    
  • LTSER Zone Atelier Plaine and Val de Sevre
  • National Institute of Agricultural Research (INRA)
  • University of La Rochelle

UKÄ Subject classification

Ecology
Environmental Sciences related to Agriculture and Land-use


Publication identifier

DOI: https://doi.org/10.1073/pnas.1906419116

Permanent link to this page (URI)

https://res.slu.se/id/publ/101291