Jean-Sauveur Ay

Integrated models, scenarios and dynamics of climate, land use and common birds

Reconciling food, fiber and energy production with biodiversity conservation is among the greatest challenges of the century, especially in the face of climate change. Model-based scenarios linking climate, land use and biodiversity can be exceptionally useful tools for decision support in this context. We present a modeling framework that links climate projections, private land use decisions including farming, forest and urban uses and the abundances of common birds as an indicator of biodiversity. Our major innovation is to simultaneously integrate the direct impacts of climate change and land use on biodiversity as well as indirect impacts mediated by climate change effects on land use, all at very fine spatial resolution. In addition, our framework can be used to evaluate incentive-based conservation policies in terms of land use and biodiversity over several decades. The results for our case study in France indicate that the projected effects of climate change dominate the effects of land use on bird abundances. As a conservation policy, implementing a spatially uniform payment for pastures has a positive effect in relatively few locations and only on the least vulnerable bird species.

Aggregated Versus Individual Land-Use Models: Modeling Spatial Autocorrelation to Increase Predictive Accuracy

The objective of this paper is to compare the predictive accuracy of individual and aggregated econometric models of land-use choices. We argue that modeling spatial autocorrelation is a comparative advantage of aggregated models due to the smaller number of observation and the linearity of the outcome. The question is whether modeling spatial autocorrelation in aggregated models is able to provide better predictions than individual ones. We consider a complete partition of space with four land-use classes: arable, pasture, forest, and urban. We estimate and compare the predictive accuracies of individual models at the plot level (514,074 observations) and of aggregated models at a regular 12 × 12 km grid level (3,767 observations). Our results show that modeling spatial autocorrelation allows to obtain more accurate predictions at the aggregated level when the appropriate predictors are used.

Efficiency and equity in land conservation: The effects of policy scale

This paper studies the effects of policy scale for land conservation schemes based on global objectives but implemented at local levels. They are explored in the classical reserve site selection framework for policy efficiency, to which we add the common social objective of equity between spatial units. We first analyze the role of the biophysical attributes of land available for conservation. These natural endowments are then combined with different implementation scales to improve a particular land-based social function: natural habitats for biodiversity. An empirical illustration, based on data from the Provence region of France, is used to explore what we identify as a policy scale trade-off between administrative units. This shows the importance of land availability in predicting the distribution of the costs and benefits of conservation schemes. In terms of equity, we find an interior solution that minimizes an inequality metric (the Gini coefficient) along policy scales. Our approach should lead to more socially acceptable conservation objectives, between the usual two extreme cases of autarky and specialization.

The Informational Content of Land Price and its Relevance for Environmental Issues

As the support of human and natural activities, land is a resource of major interest both for environmental and socio-economic issues. Research aimed at improving land 10 management and conservation has long recognized the need to integrate both issues, but a consensual and consistent framework is still lacking. We argue that land price could be one of the possible links here, as a consistent proxy for some of the multiple dimensions of values that people put 15 on land resources. We present the elementary economic theory about land price, namely the present value model, and we review the abundant empirical literature using this classical theory to study the informational content of land price. We then propose a typology of this literature, high20 lighting its strengths and weaknesses, in order to guide future environmental research which aim at drawing out some socio-economically oriented policy recommendations.