Abstract
The foliose lichen Lobaria oregana (Tuck.) Müll. Arg. is an important nitrogen-fixing component of the canopy epiphyte community in old-growth Douglas fir forests of the Pacific Northwest. This paper presents a non-destructive method for estimating the growth rate (grams per year) for L. oregana thalli of different weights.Photographs were made over a 2-year period of six in situ thalli. From a relationship of the photographic thallus area and weight of these and 31 other thalli, the dry weight of each of the six thalli is estimated through time. A growth rate is computed for each thallus and a relationship between growth rate and initial thallus weight is determined. Growth rate (grams per year) = exp (−0.8581 + 0.8444 (loge initial weight (grams))). The maximum radial growth rate of lobes of L. oregana determined from the photographs (9.4 mm/year) is comparable with rates for similar species.

This publication has 3 references indexed in Scilit: