Distributions and habitat models of epiphytic physconia in north-central California.

Abstract

I examined the distributions of eight Physconia species in northern and central California: Physconia americana, P. californica, P. enteroxantha, P. fallax, P. isidiigera, P. isidiomuscigena, P. leucoleiptes, and P. perisidiosa. Distributions are based upon lichen community data collected for the Forest Inventory and Analysis Program in over 200 permanent plots. Physconia californica was not found while P. leucoleiptes was infrequent across the landscape, occurring sporadically around the periphery of the Central Valley. Physconia isidiomuscigena occurred only once in the study plots, growing Quercus sp. in Stanislaus county. This site is unusual in that this species is often saxicolous and known primarily from southern California. The remaining Physconia species were more frequent across the landscape with distributions centered in the Central Valley. I derived habitat models for these more common species using nonparametric multiplicative regression to help explain how distributions relate to environmental variables. Distributions of P. enteroxantha, P. isidiigera, and P. perisidiosa were well described by one or more environmental gradients while P. fallax and P. americana were only weakly associated with single predictors. Considering that many Physconia species are considered nitrophilous (nitrogen-loving), the habitat models would probably be better had an estimate of ammonia deposition been included. There are not, however, any comprehensive estimates of ammonia deposition for the study area.

Citation

Jovan, Sarah. 2003. Distributions and habitat models of epiphytic physconia in north-central California. Bulletin of the California Lichen Society. 10(2): 29-35