Calibration of the STEMS diameter growth model using FIA data

Abstract

The diameter growth model used in STEMS, the Stand and Tree Evaluation and Modeling System, was originally calibrated using data from permanent growth plots in Minnesota, Wisconsin, and Michigan. Because the model has been applied in predicting growth using Forest Inventory and Analysis (FIA) data, it was appropriate to refit the model to FIA data. The model was calibrated for four species - quaking aspen, balsam fir, paper birch, and red pine using FIA data from the Aspen-Birch and Northern Pine Units of northeastern Minnesota. To compare the new and original calibrations of the model, it was important to use the same formulation and methodology in refitting the model, in this way differences due to the data sets would not be confounded with differences in model form or approach. Although STEMS was originally calibrated on permanent growth plot data, when applied to FIA data it produced estimates that were equivalent to those of the STEMS model that was refit to FIA data. Both models produced biased estimates that had large variation. Efforts to improve model performance should focus on improving the model form.

Parent Publication

• Integrated tools for natural resources inventories in the 21st century

Citation

Lessard, Veronica C. 2000. Calibration of the STEMS diameter growth model using FIA data. In: Hansen, Mark; Burk, Tom, eds. Integrated tools for natural resources inventories in the 21st century. Gen. Tech. Rep. NC-212. St. Paul, MN: U.S. Dept. of Agriculture, Forest Service, North Central Forest Experiment Station. 525-532.