United States
£ GBP
This study examines the diversity and ecology of calicioid lichens and fungi in westem North America, with emphasis on the humid forests and woodlands of western Oregon. The study is based on 2103 species observations from 96 survey sites, most of which were located in mature and old-growth forests along a complex environmental gradient over the Cascade Range. This material demonstrates that calicioid lichens and fungi are a diverse component in the mycoflora of western North America. The distribution and frequency status of 82 species are documented, including those of several undescribed taxa. Most species have wide circumpolar or antitropical distributions, but there are also a number of endemics, mainly on conifer resin and bark. The diversity of resinicolous calicioids in the Pacific Northwest is higher than in any comparable region of the world. This is related to the tree species composition and history of the local forests. Most of the endemic species have a coastal distribution and they probably survived Pleistocene glaciations close to their present distribution area. Calicioid communities differ between major forest zones. Site level species diversity is promoted by heterogeneity in forest structure, especially by the increasing availability of aged trees and snags, but also hardwood twigs. Mean site level species richness is highest in the foothills of interior valleys and lowest in dry forests east of the Sierra Cascade Crest. Some calicioid species in the deciduous woodlands and mixed forests of the Willamette Valley are rare and locally threatened. In humid coniferous forests site level species richness tends to decrease at both ends of the elevational gradient. The macroclimatic optima of many circumpolar calicioids are in relatively continental regions. These species are frequent in interior valleys and at higher elevations, but rare in humid coastal forests. The relative scarcity of calicioids in low-elevation rainforests is conspicuous and caused by a combination of several environmental factors, including adverse microclimate, lack of suitable substrates, bryophyte competition and disturbance by mollusks.
