ORI GIN AL PA PER Categorizing locally rare plant taxa for conservation status

The Author(s) 2010. This article is published with open access at Springerlink.com Abstract Locally rare taxa are those that are rare or uncommon within a local geo-graphical boundary while more common outside of that boundary. In addition to the rare taxa identified by global, national, and state/provincial levels, locally rare taxa are important for the preservation of species diversity and ecological processes, and therefore require effective and recognizable conservation status. Currently, there are no specific local rarity criteria in use to categorize taxa at regional jurisdictional levels. To address this need, we developed criteria for categorizing locally rare plant taxa by using the framework the Natural Heritage Network’s Element Ranking System combined with attributes of the World Conservation Union’s Red List Criteria. We then tested the efficacy of our clas-sification system (called L-ranks) on the flora of Napa County using a geographic infor-mation system and available plant distribution data for the State of California. Results indicated that 89 taxa from 34 families met the area of occupancy criteria for local rarity status. Our findings demonstrated that with available geographic data, the proposed criteria for classifying locally rare plants can be usefully applied at the county level to identify significant peripheral plant populations. The proposed L-rank system was specifically designed to be compatible with existing multi-scale conservation programs and will aug-ment the current systems in use by local organizations. By systematically classifying locally rare plants, current regulations that are applicable to locally rare taxa may be used more effectively in conservation planning and prioritizing at the county scale