Degree Type


Date of Award


Degree Name

Doctor of Philosophy



First Advisor

Joe P. Colletti

Second Advisor

Vincent A. Sposito


To satisfy our demand for food and fiber and at the same time to protect the environment on which our lives depend are the two critical issues facing us today. In this study, a sequential linear goal programming model is developed and used to examine the optimal land allocation among agricultural and forest production activities, the land use shifts between agriculture and forestry sectors, and the best management strategies for the nation's forest and range ecosystems under the alternative policies;This national level model consists of six sectors: crop, livestock, forest and range, resource availability, demand, and environment. Four goals of national production cost, soil erosion, wildlife habitats, and carbon dioxide reduction are optimized in a specific order determined by a user specified priority system under the constraints of land, irrigation water, minimum crop acreages, and the demand for agronomic crops and timber. Two future time periods, the years 2000 and 2040, are selected to analyze both the intermediate and long-run impacts of the alternative policies on the resources use and interregional production of crop, livestock, and forest products;The results indicate that the highly productive cropland will continue to be used for the crop production, and that the highly erosive and less productive cropland can be used potentially for tree plantations. When the production cost goal is set with the highest priority, the traditional forest will be established on the cropland only in the Northeast, Lake States, and Corn Belt. And, the short-rotation woody crop (SRWC) plantations, based on hardwood species such as hybrid poplars, will not be competitive with the typical agronomic crop, such as corn, soybeans, and oats. The Lake States will be the most economical region to increase the forest area, and the Corn Belt will be the most economical region to establish SRWC plantations. But the Southeast will be the most effective region to produce timber and biomass in terms of the shadow price per MBF of timber or per dry ton of biomass. When the environmental goals are considered to be more important relative to the production cost, a considerable amount of the idle cropland will be converted to forest area.



Digital Repository @ Iowa State University,

Copyright Owner

Jianbang Gan



Proquest ID


File Format


File Size

150 pages