DOI: 10.5061/dryad.kp3fv
title: Data from: Using beta diversity to inform agricultural policies and conservation actions on Mediterranean farmland

description: 1. Spatial variation in species composition (β-diversity) is an important
 component of farmland biodiversity, which together with local richness
 (α-diversity) drives the number of species in a region (γ-diversity).
 However, β-diversity is seldom used to inform conservation, due to limited
 understanding of its responses to agricultural management, and lack of
 clear links between β-diversity changes and conservation outcomes. 2. We
 explored the value of β-diversity to guide conservation on farmland, by
 quantifying the contribution of bird α- and β-diversity to γ-diversity
 variation in low- and high-intensity Mediterranean farmland, before
 (1995-1997) and after (2010-2012) the Common Agricultural Policy reform of
 2003. We further related β-diversity to landscape heterogeneity, and
 assessed the conservation significance of β-diversity changes. 3. In
 1995-1997, bird diversity was highest in low-intensity farmland, where it
 further increased in 2010-2012 due to a strong positive contribution of
 α-diversity to γ-diversity. In high-intensity farmland, diversity
 converged over time to much the same values of low-intensity farmland,
 with strong positive contributions of both α- and β-diversity. These
 patterns were largely consistent for total, farmland and species of
 European conservation concern assemblages, and less so for steppe birds.
 4. Beta diversity increased with landscape heterogeneity, particularly
 related to spatial gradients from agricultural to natural habitats in
 low-intensity farmland, and from annual to permanent crops (olive groves)
 in high-intensity farmland. The first gradient was associated with the
 replacement of steppe birds of high conservation concern by more
 generalist species, while the second was associated with the replacement
 between species with lower or higher affinity for woodland/shrubland
 habitats. 5. Synthesis and applications. In low-intensity farmland,
 β-diversity was largely stable over time, reflecting a positive
 conservation outcome related to persistence of landscape heterogeneity
 patterns required by endangered steppe bird species. In contrast,
 β-diversity in high-intensity farmland was favoured by increases in
 landscape heterogeneity driven by olive grove expansion, contributing to
 enhancement of total bird diversity. Overall, our results stress the value
 of β-diversity to understand impacts of agricultural policies and
 conservation actions, but also highlight the need of evaluating
 β-diversity changes against specific conservation goals.
description: Bird
 dataTotal number of
 individuals of each bird species recorded along each 250-m transect per
 year. Rowname - row identification including the transect code and the
 bird census year. Transect - transect code; Farmland_area - low- or
 high-intensity farmland area; Year - bird census year; Date - bird census
 date; Recorder - recorder's name.bird_data.csvBird categoriesBird species categorization according to their habitat affinities and conservation status. Species - species scientific name; All_species – All species: bird species recorded except aquatic birds because they were excluded from analyses; Farmland - Farmland birds: species associated with all farmland habitat types (e.g., arable fields, permanent crops, hedgerows); Steppe - Steppe birds: a subset of farmland birds that are rare or absent outside open grassland habitats; SPEC1-3 - Species of European Conservation Concern (SPEC1-3).bird_categories.csvHabitat dataRowname - row identification including the transect code and the time period (T0: 1995-1997, T1: 2010-2012). Transect - Transect code; Farmland_area - low- or high-intensity farmland area; Time_period - 1995-1997 or 2010-2012; woodland - percentage cover by holm woods (Quercus rotundifolia) with &gt;30% tree cover and shrub understory, old eucalyptus plantations with understory, and tree lines; open_woodland - percentage cover by holm woods with &gt;30% tree cover and grassy understory, young plantations without understory; shrubland - percentage cover by shrublands without trees or with scattered trees; streams - percentage cover by streams with vegetation (herbs, shrubs or trees); water_bodies - percentage cover by ponds and reservoirs; arable_land_with_scattered_trees - percentage cover by annual crops with scattered trees (&lt;30% tree cover); annual_dry_crops_and_fallows - percentage cover by non-irrigated annual crops (dry cereals (e.g. wheat, barley) and legumes) in rotation with ploughed fields, stubbles and fallows usually grazed by sheep or cattle; permanent_pastures - percentage cover by grassy vegetation grazed by sheep or cattle; annual_irrigated_crops - percentage cover by irrigated annual crops (corn and sunflower); permanent_crops - percentage cover by permanent irrigated and non-irrigated crops (olive groves and vineyards); human_structures - percentage cover by buildings and asphalt roads; PR_nat - natural habitats richness (no); AREA_MN_nat - mean patch area of natural habitats (ha); ED_nat - edge density of natural habitats (m2/ha); PR_crop - crop richness (no); AREA_MN_crop - mean patch area of crops (ha); ED_crop - edge density of crops (m2/ha).habitat_data.csvTransect coordinatesTransect - transect code; Latitude, Longitude - geographic coordinates of the transect centroid (WGS84); Farmland_area - low- or high-intensity farmland area.transects_information.csv