Effects of forest age and forest structure on epiphytic lichen biomass anddiversity in a douglas-fir forest

Pipp, AK Henderson, C Callaway, RM

Ak. Pipp et al., Effects of forest age and forest structure on epiphytic lichen biomass anddiversity in a douglas-fir forest, NW SCI, 75(1), 2001, pp. 12-24

49

INGLESE

Article

Environment/Ecology

NORTHWEST SCIENCE

0029-344X → ACNP

75

1

2001

12 - 24

ISI

0029-344X(200124)75:1<12:EOFAAF>2.0.ZU;2-U

Epiphytic lichens contribute to the biological diversity of old forests, bu t little is known about the changes that occur in lichen communities as for ests age and become structurally more complex. We compared forest age and f orest structure as indicators of lichen biomass, richness, and community on the Gifford Pinchot National Forest in Washington. Epiphytic lichens were sampled in 1995 and 1996 on 21, 13 ha forested units, ranging from 75 to 16 5 years old. Canopy lichen litterfall was sampled in 15, 12.5 m(2) plots pe r unit. Mean lichen litterfall biomass differed significantly between years , but species composition did not. Forest structure variables were refined using principal component analysis resulting in the first two principal com ponents accounting for 75.5% of the variation in the samples-by-structural- variables matrix. Principal components 1 and 2 represented structure and we re compared to forest age by correlating each with lichen biomass, richness , and community composition. Multiple regression was also used to test the relationship of age and eight structural variables against lichen biomass, richness, and community composition. In both years, and in both analyses, f orest structure explained more variance in lichen biomass and richness than forest age, whereas age explained more variance in lichen community compos ition. The structural variables that were important for predicting lichen b iomass differed from those predicting lichen richness. In mature forests, s tructure may be a better predictor of lichen biomass and diversity than for est age. Techniques that emphasize structure have the potential to help for est managers assess mature stands for their biological value.