Mosaic-Level Inference of the Impact of Land Cover Changes in Agricultural Landscapes on Biodiversity: A Case-Study with a Threatened Grassland Bird

Francisco Moreira,Domingos Leitão,Inês Henriques,Jorge M Palmeirim,Ivan Alonso,João P Silva,Teresa Catry,Eduardo Santos,Beatriz Estanque,Miguel Lecoq,Rui Pedroso,Ana Delgado,Patricia Silva,Márcia Pinto,Rohan H Clarke

doi:10.1371/journal.pone.0038876

Francisco Moreira, Domingos Leitão + Show 13 more

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https://doi.org/10.1371/journal.pone.0038876

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Abstract

Changes in land use/land cover are a major driver of biodiversity change in the Mediterranean region. Understanding how animal populations respond to these landscape changes often requires using landscape mosaics as the unit of investigation, but few previous studies have measured both response and explanatory variables at the land mosaic level. Here, we used a “whole-landscape” approach to assess the influence of regional variation in the land cover composition of 81 farmland mosaics (mean area of 2900 ha) on the population density of a threatened bird, the little bustard (Tetrax tetrax), in southern Portugal. Results showed that ca. 50% of the regional variability in the density of little bustards could be explained by three variables summarising the land cover composition and diversity in the studied mosaics. Little bustard breeding males attained higher population density in land mosaics with a low land cover diversity, with less forests, and dominated by grasslands. Land mosaic composition gradients showed that agricultural intensification was not reflected in a loss of land cover diversity, as in many other regions of Europe. On the contrary, it led to the introduction of new land cover types in homogenous farmland, which increased land cover diversity but reduced overall landscape suitability for the species. Based on these results, the impact of recent land cover changes in Europe on the little bustard populations is evaluated.

Highlights

Mediterranean ecosystems are amongst those ecosystem types predicted to undergo the greatest biodiversity changes in the long term [1]
Proportion of cereal, derived from CORINE corrected by field data Proportion of irrigated annual crops, derived from CORINE Proportion of agro-forestry systems, derived from CORINE Proportion of permanent crops, derived from CORINE Proportion of shrublands, derived from CORINE Proportion of ploughed fields, derived from CORINE corrected by field data Proportion of forests, derived from CORINE Proportion of mixed systems, derived from CORINE Proportion of dry legume crops, derived from CORINE corrected by field data Number of land cover types Equitability of land cover types
We used a ‘‘whole land mosaic’’ approach [20] to explore the relationship between the regional variation in land cover composition and the population density of a threatened bird in 81 land mosaics spread across southern Portugal

Summary

Introduction

Mediterranean ecosystems are amongst those ecosystem types predicted to undergo the greatest biodiversity changes in the long term [1]. Within Mediterranean Europe, vast regions of the Iberian Peninsula are covered by agricultural landscapes known as pseudosteppes, characterised by a mosaic of land covers including cereal crops, dry legumes, ploughed fields, and grasslands (pastures and fallows) [9,10]. These land mosaics sustain populations of several bird species with unfavourable conservation status [6,9]. More than half of the world’s population resides in the Iberian Peninsula [11,12], where grasslands of different types (pastures, natural steppe and fallow fields) are its prime breeding habitat (e.g., [13,14,15,16,17])

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