Infodoc : Sciences, Techniques et Culture

The development of the livestock sector in the past century undergone a strong intensification. The current heterogeneity of livestock areas in France may have arisen from a spatial differentiation of intensification process. Different degrees of disconnection between livestock and land have resulted in contrasted levels of performance and impacts across areas. To date, a lot of research effort has been directed at measuring environmental impacts and economic performance of livestock systems at the farm level. Insufficient attention has been paid to the three dimensions of sustainability and to trade-offs among them. Existing livestock heterogeneities across areas also deserve more research. An approach that enables connecting livestock to land and resources, at regional level, could [...]

The development of the livestock sector in the past century undergone a strong intensification. The current heterogeneity of livestock areas in France may have arisen from a spatial differentiation of intensification process. Different degrees of disconnection between livestock and land have resulted in contrasted levels of performance and impacts across areas. To date, a lot of research effort has been directed at measuring environmental impacts and economic performance of livestock systems at the farm level. Insufficient attention has been paid to the three dimensions of sustainability and to trade-offs among them. Existing livestock heterogeneities across areas also deserve more research. An approach that enables connecting livestock to land and resources, at regional level, could bring novel insights on the role of livestock in use and transformation of resources. The goal of this PhD was to develop a holistic assessment of livestock areas using multimetric indicators encompassing positive and negative contributions. We compiled three databases at the department level: i) database 1 was related to socioeconomic, land use, and production characteristics of 88 French departments, within an extensive time frame (1938-2010); ii) database 2 included data on crop, fodder and livestock production for year 2010; iii) database 3 included measures of provision of cultural, environmental and social services for 60 departments. With the first database, we created a typology of intensification trajectories based on a multivariate approach. With the second database, we assessed the nitrogen metabolism of livestock areas, based on the material flows accounting (MFA) approach, from which we derived indicators of performance and impacts to study synergies and trade-offs. With the third database, we studied the influence of past intensification on the current provision of services by the livestock sector. A multivariate approach was used to assess how different rates of change in intensification variables determined contrasted levels of services. First, we showed that the intensification of the French livestock sector was spatially differentiated and based on four trajectories, ranging from extensive to intensive livestock areas, and from crop specialized to areas where livestock had a small share of national production. Livestock productivity and stocking rates had a 3 fold increase in intensive areas, whereas extensive areas had a 1.6 fold increase. Crop specialized areas lose more than half of their original fodder area, and tripled the average farm size and more than quadrupled their labor productivity. Non-dominated livestock areas lose 30% of initial livestock population, and half of their initial fodder area. Second, the study of synergies and trade-offs revealed that gains in efficiency and economies of scale, often compromised other dimensions, e.g. through increased environmental impacts. The spatial analysis of relationship between performance and impacts revealed two types of synergies linked to the type of impact, either land or product-based. Both of which were in trade-off. Third, we showed that the provision of services was spatially structured and based on three types of service bundles, determined by different rates of change in intensification variables. Changes towards grazing systems resulted in higher provision of environmental and cultural services, whereas changes towards intensive systems resulted in higher levels of social services; but this was achieved at the cost of environmental services. This PhD thesis furthered the understanding on the temporal trajectories of livestock sector across areas in France. This knowledge could help to improve livestock sustainability. Our work provided knowledge on the drivers that shaped current intensification patterns and the provision of cultural, environmental and social services. It could be used to examine options for desirable longterm changes of the livestock sector.
--
Au cours du XXème siècle, l’élevage français a connu un formidable développement dont la poursuite se trouve actuellement fragilisé. L’effort de recherche sur la durabilité de l’élevage s’est focalisé sur la performance économique et environnementale, principalement au niveau de l’animal et de la ferme. Peu de travaux ont abordé les trois piliers de la durabilité à des échelles territoriales où les différentes filières animales se combinent. Une approche articulant l’élevage de ruminants et monogastriques à l’occupation du sol et à l’utilisation des ressources au niveau territorial fait actuellement défaut. Cette thèse développe une évaluation holistique de l’élevage dans les territoires métropolitains en mobilisant une batterie d’indicateurs abordant les contributions positives et négatives de l’élevage. Pour l’ensemble du territoire métropolitain, nous avons constitué trois bases de données à l’échelle départementale. La première base contient des indicateurs socioéconomiques, d’occupation du sol, et de production animale sur la période 1938-2010. La seconde base fournit pour 2010 des indicateurs de production animale et végétale. La troisième base fournit des indicateurs mesurant la contribution de l’élevage à la fourniture de services culturels, socioéconomiques et environnementaux. Avec la première base, nous avons modélisé les trajectoires d’intensification de l’élevage depuis 1938 et identifié les déterminants des dynamiques de changement de l’élevage. Avec la deuxième base, nous formalisé le métabolisme territorial de l’azote, duquel nous avons dérivés six indicateurs pour évaluer la durabilité de l’élevage. Avec la troisième base, nous avons modélisé le lien entre le niveau actuel de fourniture de services et les trajectoires d’intensification. Nos résultats révèlent une différentiation territoriale de l’intensification de l’élevage depuis 1938. Productivité et densité animale ont triplé dans les territoires de l’Ouest, et augmenté de 1.6 dans les territoires de l’Est et du Massif Central. Dans les territoires sans élevage, la surface fourragère principale a reculé de plus de la moitié, tandis que la taille des fermes a triplé et la productivité du travail a quadruplé. Le métabolisme territorial révèle un arbitrage entre autonomie en azote et productivité animale. Les impacts locaux (surplus azoté / ha) et globaux (émissions excrétion azoté / kg de produit) forment un arbitrage difficile à atténuer. L’analyse des contributions positives de l’élevage montre que les territoires ayant suivi une trajectoire herbagère fournissent des services sociaux, environnementaux et culturels; alors que les territoires hébergeant les élevages les plus productifs fournissent surtout des services socio-économiques (emplois). De par sa profondeur historique et sa couverture spatiale, cette thèse offre une analyse inédite de l’élevage et de ses performances dans les territoires. Elle apporte des connaissances pour identifier des leviers de durabilité pour l’élevage de demain.