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Abstract
The Forest and Analysis Program of the Northern Research Station (NRS-FIA) has re-designed Phase 3 measurements and intensified the sample intensity following a study to balance costs, utility, and sample size. The sampling scheme consists of estimating canopy-cover percent for six vegetation growth habits on 24-foot-radius subplots in four height classes and as an aerial view, and measuring tree saplings and seedlings on 6.8-foot-radius microplots. In the past two years, all of the basic submodels in SORTIE, an individual-tree distance-dependent model, were parameterized for the 50 most common tree species in the eastern U.S. by using FIA data. A significant challenge for modelers is that goodness of fit measures, such as the coefficient of determination, for the resulting growth models are often relatively low. Opportunities for using NRS-FIA data for broad-scale models include use of a non-spatial model of seedlings as a function of basal area of the entire subplot, ability to use a mortality model for seedlings, and improvement in knowledge of the impact of the species of neighboring trees. The major benefit of the new NRS-FIA sample design is a fourfold increase in sample size and integration of all vegetation measurements on the subplot (i.e., adult trees, competing vegetation, and seedlings). The primary limitation of using FIA samples is that the subplots are too small for full analysis of distance-dependent seedling dispersion around parent trees.
Parent Publication
Citation
Canham, Charles D.; McWilliams, William H. 2012. Information for forest process models: a review of NRS-FIA vegetation measurements. In: Morin, Randall S.; Liknes, Greg C., comps. Moving from status to trends: Forest Inventory and Analysis (FIA) symposium 2012; 2012 December 4-6; Baltimore, MD. Gen. Tech. Rep. NRS-P-105. Newtown Square, PA: U.S. Department of Agriculture, Forest Service, Northern Research Station. [CD-ROM]: 295-302.
