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Departments & Programs


Conditions for Land Use Transitions

Land change science has emerged as a fundamental component of global environmental change and sustainability research. This interdisciplinary field seeks to understand the dynamics of land cover and land use. The land cover is defined by the attributes of the earth’s land surface and immediate subsurface, including biota, soil, topography, surface and groundwater, and human structures. Land use is defined by the purposes for which humans exploit the land cover. Today, as much as 50% of the earth’s ice-free land surface has been transformed. Concerns about land change emerged with the realization that land surface processes influence climate (via surface albedo, the carbon cycle and evapotranspiration), the structure and function of ecosystems (via biotic diversity, soil degradation, the water cycle and the provision of food and fibers necessary for human needs) and the vulnerability of places and people to perturbations. When aggregated globally, land changes significantly affect central aspects of earth system functioning. Our research aims at better understanding land change and human-environment interactions in land systems at multiple scales of analysis.

Land change is non-linear. It is associated with other societal and biophysical system changes as human societies constantly coevolve with their environment through change, instability, and mutual adaptation. A transition is a process of system change in which the structural character of the system transforms. The concept of land use transition refers to any change in land use systems from one state to another one — e.g., from a system dominated by annual crops for local consumption to a system with large tree plantations in response to market demand or new institutions. Forest transitions are a shifts from decreasing to expanding national forest areas — i.e., from net deforestation to net reforestation - that has taken place in several European countries, in North America and, more recently, in China, India, Vietnam, Costa Rica, among others.

We try to better understand under what conditions land use transitions do take place. In some countries, a scarcity of forest products and/or a decline in the flow of services provided to societies by forest ecosystems prompted governments and land managers to establish effective afforestation programs. In other cases, changes in national forest policies — often motivated by factors outside the forestry sector - play a central role in stirring the forest transition. In other countries, economic development has created enough non-farm jobs to pull farmers off of the land, thereby inducing the conversion of fields into forests. A similar effect may occur when a national economy becomes increasingly integrated into global markets for commodities, labour, capital, tourism and ideas. Finally, in marginal regions dominated by smallholder agriculture, a significant increase in tree cover can be associated with the expansion of fruit orchards, wood lots, agroforestry systems, gardens, hedgerows, and secondary successions on abandoned pastures or fallows that are sometimes enriched with valuable species. Each of the above pathway can be associated with varying impacts on the delivery of ecosystem goods and services and with forests with different ecological qualities. Displacement of deforestation outside national borders may also help a country to recover its forest — with no net ecological gain at the global scale. Much remains to be learnt on the concept of land use transition applied to drylands, mountain regions, coastal ecosystems or peri-urban zones.