Prospective modelling of land use change in heterogeneous mountain region

International audienceThe Grenoble urban area, located in central French Alps, presents a large variety of physical and natural characteristics, resulting in contrasted heterogeneous landscapes. This territory is subject to rapid changes, including fast-paced urban and infrastructure development, raising a number of environmental and planning issues (Haida et al., 2015; Körner and Ohsawa, 2005; Tasser and Tappeiner, 2002; Zimmermann et al., 2010).The ESNET project aims to model landscape futures by 2040 in response to prospective socio-economic and climate changes, with the double aim of assessing changes in ecosystem services and providing stakeholders with relevant information on environmental issues in future planning exercises. More specifically, this study proposes to: develop scenarios of landscape changes, simulate the land use changes using a spatial explicit support, analyze land use projections and associated impacts on Ecosystem Services. Land change scenarios.This study relies on a downscaling of the "Mountain 2040" prospective scenarios produced by the Rhône-Alpes region. These were adapted to the study area combining stakeholder expert knowledge and planning documents. Three contrasted scenarios were retained: The "Business as usual" scenario is based on the main planning document SCoT (Territorial Coherence Scheme) that determines for groups of municipalities a common project for urban planning, housing, transport and business and retail areas; The "Rewilding" scenario, where strong environmental policy leads to extensive conservation of natural and mountain spaces, and urban development and business activities are concentrated in the valleys; The "Liberal" scenario, where constraints on economic activities are relaxed, a few mountain resorts are turned into recreation parks while less attractive areas are abandoned.Scenario narratives were translated into land use change rules quantified using planning documents, expert knowledge, and stakeholder expertise. Land use change modelling.We developed three models to project land use by 2040. First, we used the Dinamica probabilistic and spatialized platform to simulate urban sprawl. In all scenarios urban sprawl responds to proximity to existing built-up areas, distance to roads, elevation and slope. Scenarios then differ in their rates and constraints to urban growth. Second, we developed a GIS-based drop succession model. Crop multi-annual successions were defined using moderate resolution images MODIS for the 2008-2012 period. We then defined changes in crop successions for each scenario using expert knowledge and agronomic prospective scenarios (Mora, 2008).Third, we developed a GIS-based model for agricultural abandonment, encroachment and reforestation. Spatial pattern and rates for these changes were defined based on observed data from databases of the French Geographic/Forestry National Institutes and expert knowledge.Projections by each of these three sub-models were combined to produce a projected land use map for each scenarios.Impacts of changes on landscapes and Ecosystem Services.Land use projections for the three scenarios highlighted several key features: the magnitude of urban growth, especially around Grenoble area and the Gresivaudan valley. This dynamics worsens already existing environmental problems such as air pollution, pressure on agricultural land, and connectivity between natural areas across the three main mountain ranges; strengthening of ecological connectivity at the expense of agriculture. Intensive cropping areas are particularly sensitive and transform to more diverse local agriculture. This dynamics is favourable for forest-based and regulation ecosystem services, at the expense of economic development. land abandonment and reforestation of low production and conversely overexploitation of attractive and profitable farming areas. Abandoned land will be under favourable protection status, whereas other areas such as recreation hotspots concentrate major environmental impacts including in fragile high mountain habitats.Developing such studies in direct interaction with stakeholders is a fundamental challenge to mainstream ecosystems services into land planning (Opdam et al., 2015 ; Ahern et al., 2014)Ahern, J., Cilliers, S., Niemelä, J., 2014. The concept of ecosystem services in adaptive urban planning and design: A framework for supporting innovation. Landsc. Urban Plan. 125, 254–259. Haida, C., Rüdisser, J., Tappeiner, U., 2015. Ecosystem services in mountain regions: experts’ perceptions and research intensity. Reg Env. Change 1–16. doi:10.1007/s10113-015-0759-4Körner, C., Ohsawa, M., 2005. Mountain Systems. Chapter 24, in: Millennium Ecosystem Assessment, Ecosystems and Human Well-Being. Washington DC.Mora, O., 2008. Les nouvelles ruralités à l’horizon 2030, Quae. ed, Update Sciences and Technologies.Opdam, P., Coninx, I., Dewulf, A., Steingröver, E., Vos, C., van der Wal, M., 2015. Framing ecosystem services: Affecting behaviour of actors in collaborative landscape planning? Land Use Policy 46, 223–231.Tasser, E., Tappeiner, U., 2002. Impact of land use changes on mountain vegetation. Appl. Veg. Sci. 5, 173–184. Zimmermann, P., Tasser, E., Leitinger, G., Tappeiner, U., 2010. Effects of land-use and land-cover pattern on landscape-scale biodiversity in the European Alps. Agric. Ecosyst. Environ. 139, 13–22.