Document: DAV-3-34-81

Allometric relationship between tree diameter and total aboveground biomass may be more species independent than previously thought.

CHOJNACKY, D.C.* ¹ and J.C.JENKINS ²

USDA Forest Service, Washington, DC 20090 USA ¹
USDA Forest Service, Burlington, VT 05403 USA ²

Abstract:
Biomass equations are required to calculate carbon budget from inventory data for terrestrial forests. Although numerous species-specific equations exist, there are many gaps and confusing overlaps. This study examines biomass equations for North American pine, Pinus, species to seek patterns for generalization. A literature search found 28 diameter-based biomass equations for pine species in U.S. and Canada. Equations were compared by generating "pseudo" biomass data from the equations at 5-cm intervals for the diameter (dbh) range of original data. Comparison of data trends among equations showed little species differentiation. For example, three very different pine species (P. teada, P. edulis, and P. contorta) from the southeastern, southwestern, and northwestern corners of North America showed a similar relationship between dbh and corresponding amount of biomass. These and all other pine equations fell within a confidence interval that spanned 25 to 30% of predicted values for a generalized pine equation. Why this similar relationship in different species? Perhaps a tree's diameter is just big enough to support the mass above it. Obviously, trees distribute biomass very differently among component parts (crowns, branches, foliages, stem taper, etc.) in response to genera, genetics, site, environment, and competition. However, the sum total of components may balance out to a fairly uniform dbh-to-above ground biomass relationship for many species.

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This abstract is being presented at: 1:45 PM in session:
Oral Session #16: Plant Demography: Trees and Shrubs.