A dynamic bio-economic model for analyzing deforestation and degradation: An application to woodlands in Uganda

This study is an effort at developing a dynamic non-linear programming bio-economic model capable of analyzing deforestation and degradation processes in the Ugandan woodlands. The model is unique in capturing the entire systems behavior affecting deforestation and degradation, approximated through changes in forest area and stand density. Thus the model incorporates biological factors, such as growth, the socio-economic factors and related interactions between them. A matrix growth sub-model for the woodlands, accounting for diameter increment, mortality, recruitment and harvest of trees, was imbedded in the overall model to account for the stock changes over the planning horizon. The socio-economic factors and relations affecting the woodland deforestation and degradation processes are addressed through incorporation of three sets of activities, namely, crop cultivation, livestock raising and wood harvesting for firewood and charcoal. Demand and supply relations for these activities are linked through behavioral, structural and accounting equations. The production, consumption, and sale decisions are assumed to be made simultaneously by the households. Though, the model can be successfully used at different levels and planning horizons, a village is the decision making unit over the period 2003-2020 for the purpose of this study. The net present value of cash flows is taken as a proxy measure for utility that is sought to be maximized under six alternate scenarios, including the base scenario. Under the base scenario, 46.7% woodland clearing for cultivation and 42.1% reduction in biomass density were observed over the model planning horizon. Under the scenarios with improved agricultural yields and increased charcoal prices and taxes, the clearing of available woodland was predicted at 98.3%. Biomass density was observed to decline by about 11.9% and 15.5% with the imposition of wood harvest and charcoal quotas. It was observed that none of the policy interventions in this study resulted in reduced degradation and deforestation, which posits a dilemma to the policy makers and implementers. However, we conclude that a well implemented system for taxes or quota restrictions would enhance sustainable resource use in the remaining woodland areas. These interventions are highly limited by implementation and enforcement problems that need to be properly addressed by policy makers and planners. (c) 2006 Elsevier B.V All rights reserved.