Estimating epiphytic macrolichen biomass from topography, stand structure and lichen community data

Abstract

Abstract Question/Location: We modelled lichen epiphyte biomass in relation to topography, stand structure, and lichen community composition in the central Cascades of western Oregon. Methods: Sampling was stratified by stand structure. Epiphyte biomass was estimated based on lichen litter for three functional groups: cyanolichens, forage lichens, and matrix lichens. Regression models for estimating lichen biomass (log10kg.ha-1) were developed based on three pools of predictors, each pool demanding different levels of effort to obtain the data. First, we created models from topographic predictors that are easily extracted from GIS data. We then developed models based on both topographic and stand-structure variables. Finally, we developed models using topography, stand structure, and lichen community data. Results/Conclusions: Lichen biomass changed with elevation, cyanolichen biomass highest at low elevations (470–950 m) and forage lichen biomass highest at higher elevations (950–1470 m). Lichen biomass was lowest in even-aged young stands and highest in mature stands with remnant trees and in old-growth. Stands with remnant trees had more lichen biomass than even-aged stands. Models with the greatest explanatory power were: cyanolichen biomass predicted as a function of elevation, stand age index, the sum of Lobaria oregana and L. pulmonaria abundance, and cyanolichen species richness (R2= 0.85); forage lichen biomass predicted as a function of stand age index and, Alectoria sarmentosa abundance (R2= 0.55); and matrix lichen biomass predicted as a function of stand age index and matrix lichen abundance (R2= 0.58). These models are useful tools for understanding and predicting the distribution of epiphytic macrolichen biomass at a landscape scale.