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Advisor(s)
Abstract(s)
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
Description
Keywords
agriculture intensification biodiversity conservation bird species richness compositional heterogeneity landscape composition
Pedagogical Context
Citation
"Ecology and Evolution". ISSN 2045-7758. 7 (2017) , p.1212-1223