Deadwood Density of Five Boreal Tree Species in Relation to Field-Assigned Decay Class

Abstract

Aboveground deadwood, consisting of downed woody debris (DWD), snags, and stumps, is an important component of boreal forest ecosystem structure. Accurate deadwood density estimates are essential for evaluating ecosystem biomass and carbon stocks. The objective of this study was to examine the relationships between deadwood density, tree species, and decay status, identified in the field by morphological characteristics. We sampled DWD, snags, and stumps of trembling aspen (Populus tremuloides Michx.), paper birch (Betula papyrifera Marsh.), jack pine (Pinus banksiana Lamb.), black spruce (Picea mariana [Mill.] B.S.P.), and balsam fir (Abies balsamea [L.] Mill.) in the boreal forest of central Canada. A total of 240 samples (99 DWD, 94 snags, and 47 stumps) were collected. Decay class and tree species explained >80% of the variation in wood density of all deadwood types. Wood density decreased consistently from the lowest to the highest decay class. Tree species identity was also important in determining the relationships between wood density and field-assigned decay class for snags and stumps, but not for DWD, probably because of the five-class system used for DWD, rather than the three-class system used for snags and stumps. These results indicate that decay class and tree species are adequate predictors of deadwood density.