USING EPIPHYTE LITTER TO ESTIMATE EPIPHYTE BIOMASS

To estimate epiphyte biomass in tall forests, the only viable alternative to tree climbing methods is to sample litterfall. To evaluate the potential for using epiphyte litter to estimate epiphyte biomass, epiphyte litter and in situ epiphyte biomass were estimated independently in each of three Pseudotsuga-Tsuga heterophylla stands in the Cascade Range of Oregon and Washington, U.S.A. Litter was collected in late summers of two years in 20 2-m-radius plots. Groups of trees were felled and sampled for epiphytes. Samples were sorted into four groups: cyanolichens, alectorioid lichens, other lichens, and bryophytes. For lichens, biomass of litter (L) was strongly related to epiphyte biomass (B) (r2 = 0.87, n = 18), in about a 100:1 ratio (fit as square-root L = 0.1 x square-root B, yielding B = 100L). Year-to-year variation within stands was smaller than the differences among stands. Ten 2-m-radius plots are recommended for stands with simple structure, and 15 plots for older stands with more complex structure. The method is not recommended for bryophytes because bryophyte litterfall is highly aggregated. The method is recommended for large-scale surveys of lichens and other studies where large differences in epiphyte biomass are expected.