Estimating Understory Biomass
Stand conditions and species composition vary so much in hardwood and mixed pine-hardwood stands in the southeastern United States that understory biomass cannot be estimated with reasonable precision from overstory conditions alone. A tally of trees less than 5 inches d.b.h. by 1-inch-diameter classes can provide the basis for a reliable estimate. In a study of cruising procedures, 10-factor prism tallies made independently by two service foresters resulted in an overestimate of understory weight of 37 percent by one forester and an underestimate of 30 percent by the other. Fixed radius plot tallies in which understory tree diameters were ocularly estimated resulted in errors of 11 and 24 percent by the same foresters. Training and experience could reduce estimation errors associated with this procedure. Fixed radius plots in which individual tree diameters and total heights were measured yielded estimates of understory biomass that were only 3.7 percent above the actual understory biomass of 19.1 green tons per acre.
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Document Type: Journal Article
Affiliations: Project Leader, Utilization of Southern Timber, USDA Forest Service, Southeastern Forest Experiment Station, Athens, Georgia
Publication date: 01 February 1982