Lichen Communities on Conifers in Southern California Mountains: An Ecological Survey Relative to Oxidant Air Pollution

Abstract

In comparison with collections from the early 1900's when oxidant air pollution was essentially absent, 50% fewer lichen species were found on conifers during 3 yr (1976—1979) of collecting and sampling in the mountains of Southern California. Among the five mountains ranges studies, the San Bernardino Mountains, the region with the highest oxidant levels, had lower lichen frequency and cover values. Within the San Bernardino Study sites, lichen cover was inversely related to estimated oxidant doses. Furthermore, at sites with high oxidant levels, marked morphological deterioration of the common species Hypogymnia enteromorpha was documented. Transplants of this species from the relatively unpolluted Cuyamaca Rancho State Park into the San Bernardino Mountains exhibited similar deterioration after a year's exposure.

Lichen bioindication of biodiversity, air quality, and climate: baseline results from monitoring in Washington, Oregon, and California.

“…Since then, modern communitybased approaches, like that of the Lichen Community Indicator, have benefited greatly from a profusion of research concerning which species are reliable indicators of what pollutants (e.g., Gilbert 1986;Hawksworth and Rose 1970;Sigal and Nash 1983;van Herk 1999van Herk , 2001) and modern computer technology that permits complex statistical analyses. Through the effective use of indicator species, community-based lichen models can often be tied to the deposition of a specific type of pollution.…”

Assessment of Nitrogen deposition effects and empirical critical loads of Nitrogen for ecoregions of the United States

“…Because of the high sensitivity to Meixner Los Angeles Basin Riddell et al 2008;Hasse 1913;Ross, 1982;Sigal and Nash 1983 a N deposition is reported as throughfall Poth 2004, Fenn et al 2008) except for the serpentine grassland study and lichen studies in chaparral. In the Los Angeles Basin the range of atmospheric concentrations shown for HNO 3 indicate the concentrations at which lichens are impacted.…”

Guidelines for evaluating air pollution impacts on class I wilderness areas in California

“…Lichens are known to be sensitive receptors for air pollution, as determined by a variety of studies (Ferry and others 1973, Galun and Rohnen 1988, Nash and Wirth 1988, Ross 1982, Ryan and Rhoades 1991, Sigal and Nash 1983. Water and gas exchange proceed uninhibited over the entire surface of a lichen because there are no stomata or cuticles to exclude gases.…”

“…These sensitivity classes are based on pollutant effects on Hypogymnia enteromrph, which commonly grows on trees in the mixed conifer forest of California. Morphological and reproductive changes have been measured in this species under field and experimental conditions mash 1988, Nash and Sigall979, Nash andSigd 1980, Sigal andNash 1983). The classes with respect to owne exposure can be characterized in some detail for H. enterommphu and for other species in somewhat less detail (tabk 7).Owne exposures at the highest level (> 70 ppb) have caused the loss of up to 50 percent of all lichen species present in some a r m of mixed conifer forest in southern California (Sigal and Nash 1983).…”

“…Morphological and reproductive changes have been measured in this species under field and experimental conditions mash 1988, Nash and Sigall979, Nash andSigd 1980, Sigal andNash 1983). The classes with respect to owne exposure can be characterized in some detail for H. enterommphu and for other species in somewhat less detail (tabk 7).Owne exposures at the highest level (> 70 ppb) have caused the loss of up to 50 percent of all lichen species present in some a r m of mixed conifer forest in southern California (Sigal and Nash 1983). It is assumed that morphological changes observed in the field in southern California are, in fact, caused by ozone rather than by N or S pollution.…”