Lichens in relation to management issues in the Sierra Nevada national parks
The central and southern Sierra Nevada are subjected to high levels of ozone, high and increasing nitrogen deposition, and unknown quantities of pesticides such as organophosphates from agricultural emissions in the Central Valley. Fire regimes have changed greatly over time, from relatively frequent fire historically, to fire exclusion, to its reintroduction as prescribed fire. Parts of the Sierra parks have been grazed by livestock, and some of this persists today. On top of these factors, climate is likely to change rapidly.
Although a large literature exists on human impacts on lichens, almost nothing is known on this topic in the Sierra Nevada specifically. We are largely ignorant of the biodiversity, ecology, and ecological roles of lichens in the Sierra Nevada Park system (the “Sierra parks”: Sequoia and Kings Canyon National Park, Yosemite National Park, and Devils Postpile National Monument ). This paper synthesizes existing data, written reports and other information about lichens in and near the Sierra Nevada parks, as a first step toward developing better baseline data and assessing lichen populations or communities as potential indicators of ecosystem change.
Lichens are diverse in their ecosystem roles and functional significance. Organizing the hundreds of lichen species present in the Sierra parks into functional groups helps us to understand, interpret, inventory, and monitor the diversity of lichens. We therefore divided lichens of the Sierra parks into the following functional groups: forage lichens, nitrogen fixers, acidophiles, wolf lichens, crustose lichens on rock, crustose lichens on bark and wood, biotic soil crusts, aquatic, other green algal macrolichens, and pin lichens (calicioids).
Management issues that relate to lichens include biodiversity, air quality, water quality, fire, grazing, and the possibility of draining Hetch Hetchy Reservoir. Existing lichen data from the west slope of the Sierra Nevada, of relevance to the management of Sierra parks include: extensive lichen community data from the Forest Inventory and Analysis program (FIA), a few floristic studies focused on the parks, photo points on prescribed fire transects, lichen biomass estimates from four locations, elemental analysis of lichens from a small number of locations, lichen communities in relation to various nitrogen species in Kings River watershed, the Western Airborne Contaminants Assessment Project, Bryoria fremontii studies at Teakettle Experimental Forest, and herbarium databases.We recommend the following short list for future inventory and monitoring work: population status and trend of Bryoria fremontii, macrolichen community monitoring, revise and update the inventory of lichen biodiversity, and preliminary surveys of lichens in neglected habitats.
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