Citation:

Impact/Purpose:

D-GFAM allows for terrestrial emissions, mitigation, and impacts analyses by enhancing global economic modeling of both detailed forestry and agriculture land-use and market activity and general equilibrium modeling of the relative role of forestry and agriculture in the global economy. The model can provide detailed insights into economic and mitigation behavior and opportunities and inform larger scope general equilibrium and integrated assessment modeling.

Description:

D-GFAM was created by introduction of aggregate crop and livestock sectors to the Global Timber Model. D-GFAM maximizes net present value of global welfare in the forestry, crop, and livestock sectors by choosing outputs, land areas and inputs. Global consumption for each product is the sum of regional production, and there is a single global price trend for each commodity. The model is solved for 16 regions, with up to 18 agro-ecological zones (AEZs) within each region 6 timber types in each AEZ. Production in the forest sector is based on the dynamic optimization approach in Sedjo and Lyon (1990), Sohngen et al (1999), and Sohngen and Mendelsohn (2003; 2007). Production functions for crop and livestock sectors are adapted from the GTAP model (Hertel, 1997). The production structures were modified to include explicit heterogeneous land endowments as in Hertel et al. (2009b). The supply side of the land market is modeled via a constant elasticity of transformation function (CET). Using the CET structure, the model derives land supply functions for each of the potential land uses (one livestock, one crop, and up to six forest types), a function of own rent, the other rents, and an endowment.

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