Biomass of Epiphytic Lichens and Bryophytes on Abies lasiocarpa on a Mt. Baker Lava Flow, Washington

Abstract

Biomass was estimated in stands at about 600 m elevation. Epiphytes were divided into three categories: lichens with blue-green phycobionts, lichens with green phycobionts only, and bryophytes. Total biomass was 3500 kg ha-1: 1220 kg ha-1 for lichens with blue-green phycobionts, 5300 kg ha-1 for lichens with green phycobionts only, and 1770 kg ha-1 for bryophytes. Nitrogen-fixing lichens can play an important role by naturally fertilizing forest com- munities. Although they often represent a negligible portion of the total biomass, they may provide much of the newly fixed nitrogen (Pike 1978). Previous studies of communities of nitrogen-fixing lichens have been done in old-growth conifers of western Oregon (Denison 1973; Pike et al. 1977), in oak and ash forests of North Carolina (Becker et al. 1977), and on various ground-dwelling species in sub-polar regions (Alexander 1975). An unusual community of epiphytes on Abies lasiocarpa (Hook.) Nutt. (subalpine fir) on a Mt. Baker, Washington, lava flow appeared to contain large quantities of diphyco- philous and cyanophycophilous lichens. These species have blue-green-algal phycobionts and presumably fix atmospheric nitrogen. The study reported here was designed to esti- mate the biomass of these lichens and the associated chlorophycophilous lichens (with green-algal phycobionts only) and bryophytes.