Assessing the influence of environmental variables in the birds response to agricultural intensification in the Dry Chaco

DECARRE, JULIETA; MACCHI, LEANDRO; GOIJMAN, ANDREA; MASTRANGELO, MATIAS; GAVIER, GREGORIO; BLENDINGER, PEDRO G.; MURRAY, FRANCISCO; PIQUER-RODRÍGUEZ, MARIA; SEMPER-PASCUAL, ASUNCIÓN; KUEMMERLE, TOBIAS

Congreso; Ornithological Congress of the Americas ? XVII RAO / XXIV CBO; 2017

Over the past two decades, farmland intensification and expansion at the expense of natural habitats has drawn conservationist attention to the Chaco region. Its effects on biodiversity have been scarcely studied at regional scale, disregarding the potential interaction of landscape structure and local management intensification. We analyzed how agricultural intensification affects bird communities across the Dry Chaco region taking into account habitat availability and climatic heterogeneity. Data for bird occurrence was aggregated from 2009 to 2014 (n=235 sites). We modelled occupancy and estimate richness per site using Bayesian hierarchical multi-species models, and evaluated its relationship to: a) net annual revenue per hectare, as an indicator of intensification; b) percentage of forest cover within a six kilometers buffer, and c) annual rainfall, to account for environmental heterogeneity. Agricultural intensification resulted in an overall negative effect on bird occupancy at community level (beta: -0.373, CRI95%: -0.524; -0.219). Whereas forest cover (beta: 0.168, CRI95%: 0.075; 0.260) and annual rainfall (beta: 0.155, CRI95%: 0.075; 0.236) showed a positive relationship with the bird community. There was a positive interaction between forest cover and annual revenue (beta: 0.360, CRI95%: 0.294; 0.428) for most species, resulting in a mitigation of the negative effects from the latter as forest cover increased. Our results demonstrate that there is a differential effect of agricultural intensification depending on forest habitat availability in the surrounding landscape. This information can contribute to integrate biodiversity conservation and land use planning to achieve sustainable productive landscapes.