Comparing algorithms for estimating foliar biomass of conifers in the Pacific Northwest

Abstract

Accurate estimates of foliar biomass (FB) are important for quantifying carbon storage in forest ecosystems, but FB is not always reported in regional or national inventories. Foliar biomass also drives key ecological processes in ecosystem models. Published algorithms for estimating FB in conifer species of the Pacific Northwest can yield signifi cantly different results, but have not been rigorously compared for species other than Douglas-fi r (Pseudotsuga menziesii (Mirb.) Franco). We compared fi ve algorithms for estimating FB for seven common coniferous species in the Pacifi c Northwest. Algorithms based on diameter at breast height (DBH), or on DBH and height, consistently yield higher estimates of FB than algorithms based on sapwood area. At the tree level, differences between algorithms increased with increasing DBH for all species, but their order and magnitude differed by species. At the stand level, differences among algorithms were muted by the mix of species and diameter classes that contributed to total FB of stands of different seral stages and species composition. Signifi cant differences among estimates of FB from different algorithms show the need for consistent methods for estimating FB for carbon accounting, tests of the sensitivity of ecosystem models to these differences, and more field observations to compare algorithms.