Classification Systems

We utilized established classification systems to determine the sensitivity of habitat to development. Established classifications systems have proved useful in determining conservation priorities. Of the attributes provided with each CNDDB element occurrence, we decided that Global Rank, State Rank, listing under the Endangered Species Act (ESA), listing under the California State Endangered Species Act (CESA), and listing under the California Native Plant Society (CNPS) List would best capture how sensitive a species would be to anthropogenic disturbance. These scores were used as proxies for sensitive habitat, under the assumption that the more rare or endangered the species, the more likely it is that the species would be sensitive to habitat disturbance from solar development.

Global Rank and State Rank
Global Rank and State Rank are classifications used by NatureServe, a non-profit conservation organization that works with its network of natural heritage programs to provide information about rare and endangered species and threatened ecosystems.1 Both Global Rank (GRank) and State Rank (SRank) are conservation status ranks that are assessed and determined by NatureServe scientists and its collaborators.2 GRank uses a numbered status rank, 1 to 5, to reflect a species’ risk of extinction. These numbered ranks include:

1 = critically imperiled
2 = imperiled
3 = vulnerable
4 = apparently secure
5 = secure

GRank refers to a species “global” status, while SRank refers to a species’ status within a particular state or province.3 These different geographic focuses can result in different GRank and SRank for a particular species. For example, the desert tortoise (Gopherus agassizii) has a GRank of G4, but in California it has a SRank of S2.

State Ranks in California are comprised of two parts. The number directly following the “S” indicates the number of element occurrences, individuals, or habitat; the number after the decimal is a threat designation. The first numbers indicate the following:

S1 = Less than 6 element occurrences OR less than 1,000 individuals OR less than 2,000 acres
S2 = 6 to 20 element occurrences OR 1,000 to 3,000 individuals OR 2,000 to 10,000 acres
S3 = 21 to 100 element occurrences OR 3,000 to 10,000 individuals OR 10,000 to 50,000 acres
S4 = Apparently secure within California, but there is some threat or somewhat narrow habitat
S5 = Demonstrably secure to ineradicable in California

The threat designations are the following:

0.1 = very threatened
0.2 = threatened
0.3 = no current threats known

The ranks S4 and S5 do not have a threat ranks associated with them. For the purposes of this study, we will refer to “element occurrences” of a species as “sensitive habitat” of a species from here onward.

Federal Endangered Species Act
The ESA is the primary species protection law in the nation. The stated purpose of the act is the “protect and recover imperiled species and the ecosystems on which they depend.”4 Under the ESA, which lists both plants and animals, species may be listed as “Endangered” (the species is in danger of extinction throughout all or a significant portion of its range) or “Threatened” (the species is likely to become endangered within the foreseeable future).5 The following categories are used in the CNDDB:

  1. Federally listed as Endangered
  2. Federally listed as Threatened
  3. Proposed for federal listing as Endangered
  4. Proposed for federal listing as Threatened
  5. Candidate for federal listing
  6. Species of Concern
  7. None – no federal status
  8. Delisted – previously listed

California State Endangered Species Act
The CESA generally follows the main provisions of the Federal ESA.6 Under the CESA, which lists native plants and animals, a species can be listed as “Endangered” (a species or subspecies in serious danger of becoming extinct throughout all or a significant portion of its range),7 “Threatened” (a species or subspecies not presently threatened with extinction but is likely to become an endangered species in the foreseeable future in the absence of special protection and management),8 “Rare” (a species or subspecies not presently threatened with extinction, but is in such small numbers throughout its range that it may become endangered if its present environment worsens),9 “Candidate” (a species or subspecies that is under review by the California Department of Fish and Game for listing).10 The following categories are used in the CNDDB:

  1. State listed as Endangered
  2. State listed as Threatened
  3. State listed as Rare
  4. Candidate for state listing
  5. None – no state status
  6. Delisted – previously listed

Listing under the ESA is not a prerequisite for listing under the CESA, and vise-versa. A species may have a different listing category under each Act.

California Native Plant Society

The CNPS is a statewide non-profit organization that seeks to increase understanding of and preserve California’s native flora for future generations.11 The CNPS tracks the conservation status of hundreds of rare and endangered plant species in California and shares this information with the CNDDB.12 Species undergo a rigorous, science-based review process before being placed on the CNPS Inventory of Rare and Endangered Plants of California; the Inventory is widely regarded as the standard for information on the rarity and endangerment status of plants in California.13 List categories include:

1A = Plants presumed extinct in California
1B = Plants rare, threatened, or endangered in California and elsewhere; AND
     1B.1 = ...seriously threatened in California
     1B.2 = ...fairly threatened in California
     1B.3 = ...not very threatened in California
2 = Plants rare, threatened, or endangered in California, but more common elsewhere; AND
     2.1 = ...seriously threatened in California
     2.2 = ...fairly threatened in California
     2.3 = ...not very threatened in California
3 = Plants about which we need more information
     3.1 = ...seriously threatened in California
     3.2 = ...fairly threatened in California
     3.3 = ...not very threatened in California
4 = Plants of limited distribution
     4.1 = ...seriously threatened in California
     4.2 = ...fairly threatened in California
     4.3 = ...not very threatened in California

Limitations of Established Classification Systems
Despite the fact that all five of these classification systems are well-established, relied upon methods for assessing a species’ level of rarity or endangerment, they still face some limitations. Population estimates and trends for many species remain unstudied or have not been updated in many years, resulting in an inaccurate or unspecified assessment of rarity or endangerment. The ESA or CESA lists may be disproportionately weighted towards charismatic megafauna or inherently biased towards species that have social and cultural value, not necessarily biological value.14 This is not to say that these classification systems should not be used, but that users need to be aware of the potential limitations of this tool.

1 NatureServe, About Us, http://www.natureserve.org/aboutUs/.

2 NatureServe, NatureServe Conservation Status, http://www.natureserve.org/explorer/ranking.htm.

3 NatureServe, NatureServe Conservation Status, http://www.natureserve.org/explorer/ranking.htm.

4 U.S. Fish & Wildlife Service, ESA Basics: More Than 30 Years of Conserving Endangered Species, http://www.fws.gov/endangered/factsheets/ESA_basics.pdf.

5 U.S. Fish & Wildlife Service, ESA Basics: More Than 30 Years of Conserving Endangered Species, http://www.fws.gov/endangered/factsheets/ESA_basics.pdf.

6 California Environmental Resources Evaluation System, California Wetlands Information System: California Endangered Species Act, http://ceres.ca.gov/wetlands/permitting/cesa_summary.html.

7 Legislative Counsel of California, California Law: California Fish and Game Code Section 2062, http://www.leginfo.ca.gov/cgi- bin/displaycode?section=fgc&group=02001-03000&file=2050-2068.

8 Legislative Counsel of California, California Law: California Fish and Game Code Section 2067, http://www.leginfo.ca.gov/cgi- bin/displaycode?section=fgc&group=02001-03000&file=2050-2068.

9 Legislative Counsel of California, California Law: California Fish and Game Code Section 1901, http://www.leginfo.ca.gov/cgi- bin/displaycode?section=fgc&group=01001-02000&file=1900-1913.

10 Legislative Counsel of California, California Law: California Fish and Game Code 2068, http://www.leginfo.ca.gov/cgi- bin/displaycode?section=fgc&group=02001-03000&file=2050-2068.

11 California Native Plant Society, About CNPS, http://www.cnps.org/cnps/about/.

12 California Native Plant Society, Rare Plant Program, http://www.cnps.org/cnps/rareplants/.

13 California Native Plant Society, Rare Plant Program, http://www.cnps.org/cnps/rareplants/.

14 Amy Fesnock, Threatened and Endangered Species Lead, Bureau of Land Management, Personal Communication, December 8, 2009.