title: Combined effects of landscape composition and heterogeneity on farmland avian diversity.
abstract: Conserving biodiversity on farmland is an essential element of worldwide efforts for reversing the global biodiversity decline. Common approaches involve improving the natural component of the landscape by increasing the amount of natural and seminatural habitats (e.g., hedgerows, woodlots, and ponds) or improving the production component of the landscape by increasing the amount of biodiversity-friendly crops. Because these approaches may negatively impact on economic output, it was suggested that an alternative might be to enhance the diversity (compositional heterogeneity) or the spatial complexity (configurational heterogeneity) of land cover types, without necessarily changing composition. Here, we develop a case study to evaluate these ideas, examining whether managing landscape composition or heterogeneity, or both, would be required to achieve conservation benefits on avian diversity in open Mediterranean farmland. We surveyed birds in farmland landscapes of southern Portugal, before (1995-1997) and after (2010-2012) the European Union's Common Agricultural Policy (CAP) reform of 2003, and related spatial and temporal variation in bird species richness to variables describing the composition, and the compositional and configurational heterogeneity, of the natural and production components of the landscape. We found that the composition of the production component had the strongest effects on avian diversity, with a particularly marked effect on the richness of farmland and steppe bird species. Composition of the natural component was also influential, mainly affecting the richness of woodland/shrubland species. Although there were some effects of compositional and configurational heterogeneity, these were much weaker and inconsistent than those of landscape composition. Overall, we suggest that conservation efforts in our area should focus primarily on the composition of the production component, by striving to maximize the prevalence of biodiversity-friendly crops. This recommendation probably applies to other areas such as ours, where a range of species of conservation concern is strongly associated with crop habitats.
authors.affiliation: CIBIOCentro de Investigação em Biodiversidade e Recursos Genéticos/InBIO Universidade do Porto Vairão Portugal; CEABN CIBIOCentro de Investigação em Biodiversidade e Recursos Genéticos/InBIO Instituto Superior de Agronomia Universidade de Lisboa Lisboa Portugal.
authors.forename: Joana
authors.identifier: 0000-0002-4100-8012
authors.initials: J
authors.lastname: Santana
authors.affiliation: CIBIOCentro de Investigação em Biodiversidade e Recursos Genéticos/InBIO Universidade do Porto Vairão Portugal; CEABN CIBIOCentro de Investigação em Biodiversidade e Recursos Genéticos/InBIO Instituto Superior de Agronomia Universidade de Lisboa Lisboa Portugal; CIBIOCentro de Investigação em Biodiversidade e Recursos Genéticos/InBIO Universidade de Évora Évora Portugal.
authors.forename: Luís
authors.identifier: 0000-0002-9768-1097
authors.initials: L
authors.lastname: Reino
authors.affiliation: Game & Wildlife Conservation Trust Allerton Project Loddington Leics UK.
authors.forename: Chris
authors.initials: C
authors.lastname: Stoate
authors.affiliation: CIBIOCentro de Investigação em Biodiversidade e Recursos Genéticos/InBIO Universidade do Porto Vairão Portugal; CEABN CIBIOCentro de Investigação em Biodiversidade e Recursos Genéticos/InBIO Instituto Superior de Agronomia Universidade de Lisboa Lisboa Portugal.
authors.forename: Francisco
authors.initials: F
authors.lastname: Moreira
authors.affiliation: CEF Centro de Estudos Florestais Instituto Superior de Agronomia Universidade de Lisboa Lisboa Portugal.
authors.forename: Paulo F
authors.initials: PF
authors.lastname: Ribeiro
authors.affiliation: CEF Centro de Estudos Florestais Instituto Superior de Agronomia Universidade de Lisboa Lisboa Portugal.
authors.forename: José L
authors.initials: JL
authors.lastname: Santos
authors.affiliation: Department of Ecology, Evolution, and Behavior University of Minnesota Saint Paul Minnesota USA.
authors.forename: John T
authors.identifier: 0000-0002-0864-1676
authors.initials: JT
authors.lastname: Rotenberry
authors.affiliation: CIBIOCentro de Investigação em Biodiversidade e Recursos Genéticos/InBIO Universidade do Porto Vairão Portugal; CEABN CIBIOCentro de Investigação em Biodiversidade e Recursos Genéticos/InBIO Instituto Superior de Agronomia Universidade de Lisboa Lisboa Portugal.
authors.forename: Pedro
authors.identifier: 0000-0001-8164-0760
authors.initials: P
authors.lastname: Beja
keywords: agriculture intensification; biodiversity conservation; bird species richness; compositional heterogeneity; configurational heterogeneity; landscape composition