PS 84-118 - Modelling the Forest Transition

Friday, August 12, 2011
Exhibit Hall 3, Austin Convention Center
Christopher Pagnutti, Department of Applied Mathematics/School of Environmental Sciences, University of Western Ontario and University of Guelph, London, ON, Canada, Madhur Anand, Global Ecological Change Laboratory, School of Environmental Sciences, University of Guelph, Guelph, ON, Canada, Chris Bauch, Mathematics and Statistics/Ecology and Evolutionary Biology, University of Guelph and Princeton University, Guelph, ON, Canada and Simon A. Levin, Ecology and Evolutionary Biology, Princeton University, Princeton, NJ
Background/Question/Methods

The forest transition (a change from net deforestation to net reforestation) has been observed in many parts of the world during the last two centuries.  However, it is debated whether all countries necessarily undergo this transition, and if not, what conditions are necessary for it to occur.   Simple computational resource-use models suggest that increasing productivity of resource extraction per unit area (e.g., agricultural production per unit area of forest cleared for agriculture) can ultimately result in less overall resource consumption and thus a forest transition, assuming that demand for the resource remains constant. This is a rather limited view however on human use of common pool resources and also does not provide meaningful parameters with which the underlying dynamics can be understood. Others have pointed out that there are many other pathways by which a forest transition can occur, each associated with a different mechanism.  However, mathematical modeling of forest transitions is still in a fairly nascent stage, especially with respect to understanding and predicting the effects of different pathways.  Our objective was to develop a mathematical model of the forest transition that includes several previously hypothesized pathways. 

Results/Conclusions

We developed a simple deterministic mathematical model of land use as impacted by ecological dynamics and human decision-making.  The model identifies several possible states for patches of land (e.g. agriculture, forest) and formulates processes by which a patch of land changes from one state to another.  Potential forest transition pathways that are analyzed include those related to forest scarcity, land use intensification, economic development, and globalization.  The model reproduces the observed forest transition that occurred in France in the 19th century.  We analyze the parameter space of the model to identify regions that give rise to the forest transition and we discuss implications for forest policy.

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