Difficultés avec les Modèles statistiques Hiérarchiques en écologie (DMH) : propositions pour le groupe de travail du GDR Ecostat

National audienceNous présentons ici les principales difficultés numériques rencontrées dans l'utilisation des modèles statistiques hiérarchiques en écologie et proposons l'organisation d'un groupe de travail sur le sujet

Modèles statistiques hiérarchiques en écologie : propositions pour un groupe de travail au sein du GDR Ecostat

National audienceNous présentons ici les principales difficultés numériques rencontrées dans l'utilisation des modèles statistiques hiérarchiques en écologie et proposons l'organisation d'un groupe de travail sur le sujet

Optimal allocations of agricultural intensity reveal win-no loss solutions for food production and biodiversity

publication en ligne 23 avril 2016Reconciling biodiversity conservation and food production may require the fine-tuning of both agricultural intensity and its spatial allocation. Here, we explored whether the optimization of allocation of intensity could improve food production and biodiversity outcomes. We developed a spatially explicit, multi-criteria optimization model for agricultural intensity allocation at the scale of France and at the resolution of small agricultural regions (SARs) with a mean area of 669.6 km2. Three thousand allocations were randomly simulated and then optimized under three scenarios: intensification, extensification, and reallocation. Optimization was based on food production and biodiversity outcomes using several metrics, such as habitat specialization and trophic level, that reflect the composition of farmland bird communities. The optimization was based on derived statistical relationships between intensity and the production and biodiversity metrics at the SAR scale using national agricultural statistics and bird census data. Simulations showed that optimal allocations modulated the trade-off among criteria and led to increased efficiency, with optimal extensification increasing biodiversity and minimizing production losses. Furthermore, we revealed “win-no loss” solutions. For example, optimal intensification increased production with almost no biodiversity loss and optimal reallocation benefited biodiversity with almost no cost to production. A variety of agricultural intensity levels were necessary to maintain a diversity of farmland bird communities at the national scale. Although we demonstrate that optimal allocation of intensity can be a powerful means of reconciling diverse criteria at the national scale, its implementation will require new mechanisms for spatially targeted and coordinated policies

Forecasting Large-Scale Habitat Suitability of European Bustards under Climate Change: The Role of Environmental and Geographic Variables

Distribution of the great and the little bustard in the study area that comprises the majority of Europe, North Africa and Southwest Asia according to Hagemeijer & Blair (1997), Eken & Magnin (2000), Alonso et al. (2005) and Palacin & Alonso (2009). Regarding climatic variables, raw temperature and precipitation data were extracted from WorldClim (http://www.worldclim.org/) according to the Climgen Statistical Downscaling for the ‘current’ period 1961-1990 and for the future periods 2050 and 2080, the latter periods according to the emission scenario A1B in three different general circulation models (GCMs): CGCM31, ECHAM5 and HADCM3. We calculated three bioclimatic variables: cumulative annual rainfall, temperature range between July and January, and the mean temperature during the reproductive period for both species, i.e. between April and July. We also obtained the mean slope of the UTM cell (derived from GLOBE et al. 1999) and the percentage of dry crops and pasturelands in each cell (obtained from the USGS Land Cover, http://edc2.usgs.gov/glcc/glcc.php). Additionally, we included the mean value of human population density (obtained from ORNL 2009).Distribution of the great and the little bustard and values of environmental and geographic variables in each 50 km x 50 km UTM cell of the Western Palearctic.Peer reviewe