## 3 Results and Discussion  
### Land Use Impacts of USA Ethanol Mandate  
Several studies have used the GTAP-BIO model which operates based on a land supply tree with a one-nest land cover structure and implements uniform land transformation elasticity values of \(\mathrm{ETL1}=-0.2\) and \(\mathrm{ETL2}=-0.5\) (or recently \(\mathrm{ETL2}=-0.75\)) to evaluate the land use impacts of the USA ethanol mandate. The results from these studies indicate that around 50 percent of the expansion in global cropland due to USA ethanol occurs in the USA and that much of that is forest. The following experiments show that moving from this set up to a new GTAP-BIO model which operates based on a land supply tree with a two-nest land cover structure and implements regional land transformation elasticities obtained from regional-historical observations could entirely alter this picture To analyze the impacts of this transition on estimates of induced land use changes due to USA ethanol production the following four experiments are designed and simulated: \begin{table}
\begin{tabular}{l l l l l l} \hline \hline
**Regions** & **Rank in land cover change** & **Tuned ETL1** & **Tuned ETL1\({}_{\mathrm{F}}\)** & **Tuned ETL1\({}_{\mathrm{P}}\)** & **Tuned ETL2** \\ \hline \hline \multirow{2}{*}{
\begin{tabular}{l} \(\mathrm{Oth\_Europe}\) \\ \end{tabular} } & \multirow{2}{*}{Very Low} & \(-0.02\) & \(-0.018\) & \(-0.0218\) & \(-0.25\) \\ \cline{3-6}  & & \(-0.02\) & \(-0.018\) & \(-0.0218\) & \(-0.25\) \\ \cline{3-6}  & & \(-0.02\) & \(-0.018\) & \(-0.0218\) & \(-0.25\) \\ \cline{3-6}  & & \(-0.02\) & \(-0.018\) & \(-0.0218\) & \(-0.75\) \\ \cline{3-6}  & & \(-0.02\) & \(-0.018\) & \(-0.0218\) & \(-0.25\) \\ \cline{3-6}  & & \(-0.02\) & \(-0.018\) & \(-0.0218\) & \(-0.75\) \\ \cline{3-6}  & & \(-0.02\) & \(-0.018\) & \(-0.0218\) & \(-0.25\) \\ \cline{3-6}  & & \(-0.02\) & \(-0.018\) & \(-0.0218\) & \(-0.75\) \\ \cline{3-6}  & & \(-0.02\) & \(-0.018\) & \(-0.0218\) & \(-0.75\) \\ \cline{3-6}  & INDIA & \(-0.1\) & \(-0.0909\) & \(-0.1091\) & \(-0.25\) \\ \cline{3-6}  & & \(-0.1\) & \(-0.0909\) & \(-0.1091\) & \(-0.25\) \\ \cline{3-6}  & & \(-0.2\) & \(-0.1818\) & \(-0.2182\) & \(-0.75\) \\ \cline{3-6}  & & \(-0.2\) & \(-0.1818\) & \(-0.2182\) & \(-0.5\) \\ \cline{3-6}  & & \(-0.2\) & \(-0.1818\) & \(-0.2182\) & \(-0.25\) \\ \cline{3-6}  & & \(-0.2\) & \(-0.1818\) & \(-0.2182\) & \(-0.5\) \\ \cline{3-6}  & & \(-0.3\) & \(-0.2727\) & \(-0.3273\) & \(-0.5\) \\ \cline{3-6}  & & \(-0.3\) & \(-0.2727\) & \(-0.3273\) & \(-0.5\) \\ \cline{3-6}  & & \(-0.3\) & \(-0.2727\) & \(-0.3273\) & \(-0.25\) \\ \cline{3-6}  & & \(-0.3\) & \(-0.2727\) & \(-0.3273\) & \(-0.25\) \\ \cline{3-6}  & & \(-0.3\) & \(-0.2727\) & \(-0.3273\) & \(-0.5\) \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Tuned regional land cover transformation elasticities. * _Experiment A._ An increase in corn ethanol production from its 2004 level (3.41 billion gallons [BG]) to 15 BG, using a land supply tree including a one-nest land cover structure with uniform land transformation rates of \(\mathrm{ETL1}=-0.2\) and \(\mathrm{ETL2}=-0.75\) across the world. * _Experiment B._ An increase in corn ethanol production from its 2004 level (3.41 billion gallons [BG]) to 15 BG, using a land supply tree including a one-nest land cover structure with regional land transformation rates presented in Table 1.
* _Experiment C._ An increase in corn ethanol production from its 2004 level (3.41 billion gallons [BG]) to 15 BG, using a land supply tree including a two-nest land cover structure with uniform land transformation rates of \(\mathrm{ETL1}=-0.2\) and \(\mathrm{ETL2}=-0.75\) across the world while we assume in each region \(\mathrm{ETL1_{P}}\) is 20% larger than \(\mathrm{ETL1_{F}}\).