I have just returned from a CNPS meeting where the protection of CNPS List 2 species was discussed. If you are not familiar with the CNPS Inventory of Rare & Endangered Plants, it has become the accepted authority on the status of plants, and is addressed in environmental assessment of projects. List 1A plants are considered extinct, List 1B plants are rare, threatened, or endangered in California and elsewhere , and List 2 plants are rare, threatened, or endangered in California, but more common elsewhere. For more information, see CNPS Ranking System.
The CNPS argument for protecting List 2 plants is that our populations are by definition at the edge of the range for the plant, or even a distant outlier of the plant. This would frequently involve some genetic adaption to the habitat that would otherwise be marginal to a species, and for that reason may hold the keys to the long-term survival of the species in a changed environment. Thus heat-adapted species might fare better in a warmer world. Variety is indeed the spice of life.
CNPS maintains a searchable web site of the Inventory, and it shows that San Luis Obispo County only has five List 2 plants. This is in spite of the fact that we have the westernmost extensions of Mojave Desert species, the most southerly extensions of northern Coast Range plants, and the most northerly extensions of many southern plants such as our much admired Coreopsis gigantea from the Oso Flaco Lake area.
This indicates that the rationale justifying List 2 should be applied within California, so that plants that are rare in SLO but common elsewhere should be given some sort of protection, as the same edge-of-range values would apply. The value of locally rare species is inconsistently applied, is not recognized in either State or Federal Endangered Species Acts, but is recognized under the California Environmental Quality Act.
Our chapter will be assessing all of the “edge-of-range” and “outlier” species with the aim of getting better protection at the County and City planning level.
Please contribute your knowledge to this effort.
— David Chipping