AN EVALUATION OF GROWTH SIMULATION MODELS FOR NON-INDUSTRIAL PRIVATE FOREST STEWARDSHIP PLANNING IN SOUTHERN ILLINOIS

AN ABSTRACT OF THE THESIS OF WILLIAM J. WATSON, for the Master of Science degree in Forestry, presented on August 2009, at Southern Illinois University Carbondale. TITLE: An Evaluation of Growth Simulation Models for Non-Industrial Private Forest Stewardship Planning in Southern Illinois MAJOR PROFESSOR: DR: Andrew Carver After timber is harvested, changes occur that should be recorded to provide guidelines and justification for future forest stewardship practices. In 1997, an inventory of the Scherrer property timber was conducted in order to record the impacts that might result in changes in a stand following a timber harvest and a timber stand improvement project. The timber was harvested in the summer of 1998 using a 20-inch diameter limit, with a lower limit on sugar maples and hickory species. Pre-harvest and post-harvest data were collected using a Biltmore Cruising Stick, diameter tape, 100\u27 tape measure, forester\u27s compass, and a 10-factor wedge prism. Pre-harvest data was collected on 71 plots, and post-harvest data was collected on 61 plots. The data were analyzed using the SILVAH computer program for pre-harvest and post-harvest data. The Ned\Sips program was used to run four growth simulators. The growth simulators used were FIBER, NW-TWIGS, SILVAH, and OAKSIM, each programmed for a five year time horizon after harvest. The actual relative density measured before treatment was 77 percent per acre. The field-measured post-harvest density decreased to 57 percent. The computer simulated relative density ranged between 31 to 69 percent per acre. The pre-harvest board-foot volume was 8266 International ¼\u27 scale. The actual field-measured post-harvest volume was 6591 board feet per acre. The range for simulated boardfoot volumes was 2395 to 6295 board feet per acre. The results of the study support the validity of using the NW-TWIGS simulator for stewardship planning in Southern Illinois. The NW-TWIGS model yielded results closest to the actual field measurements. FIBER and SILVAH produced the same result. OAKSIM was the least. A study of the hardwood regeneration indicates that, at present, ash is the dominant species overall. The white oak, hickory, sugar maple, and black oak volumes decreased in composition within stands. Ash, northern red oak, cherrybark oak, sweetgum, and beech composition remained largely unchanged. Whereas yellow poplar, black walnut and the chestnut oak group increased in percent presence within stands