Extinction Density of World Flora
Humphreys et al (2019) compiled a global roster of presumed
extinct seed plants. Their assessment
(based on their Supplementary Data 1 spreadsheet) tallies but 9 plants as being
extinct in California. This is
incorrect: CNPS (2019) records 22 presumed extinct plants (all seed plants). No presumed extinct plants have been rediscovered
in California since 2001 (CNPS 2019), hence this number is considered factually
correct as compared to the Humphreys et al (2019) tally. The Humphreys et al (2019) tally used as sources
CPS (1990) and Kartesz (1994), but not (CNPS 2019). Unfortunately, Humphreys et al (2019) thusly
underestimate the magnitude of extinction in the California Floristic Province.
Humphreys et al (2019) did not base their regional
extinction ranking based on area:
correcting for this (the table below), California has the 3rd
highest rate, and their Fig. 1 does not reflect this. Moreover (see the table) the 22 presumed
extinct plants in California equals or exceeds the putative highest ranked
regions given by Humphreys et al (2019).
Unfortunately, the underestimate for California is consequential, as the
Humphreys et al (2019) assessment is re-tweeted (e.g. Ledford 2019) giving the
incorrect rankings and doubtless will receive wide distribution.
Thusly,
California and the Cape Province (S. Africa) have similar magnitudes of plant
extinction density.
Extinction Density Tabulation
|
Country
|
Area (km2)
|
Extinctions
|
Extinction Density
(km2/extinction)
|
Global
Rank
|
|
Hawaii
|
28311
|
79
|
3145
|
1st
|
|
Cape Province
|
298428
|
37
|
8065
|
2nd
|
|
California
|
423970
|
22
|
19271
|
3rd
|
|
Western Australia
|
2645615
|
22
|
120225
|
4th
|
|
India
|
3287263
|
20
|
164363
|
5th
|
Humphreys et al (2019) quite correctly point out that many presumed
extinct plants have at some point been rediscovered, and this is certainly true
for California (the second table below).
Clearly on theoretical grounds (Preston 1948) it is impossible to
determine when a plant can be deemed extinct hence it is not unexpected that
over time, and 29 California plants have been ‘rediscovered’.
Presumed Extinct Plants in California
|
Date/Inventory Edition
|
Reference
|
No. Extinct Plants
|
|
1980 2nd Edition
|
Smith et al. (1980)
|
44
|
|
1984 3rd Edition
|
Smith & York (1984)
|
34
|
|
1988 4th Edition
|
Smith & Berg (1988)
|
39
|
|
1994 5th Edition
|
Skinner & Pavlick (1994)
|
34
|
|
2001 6th Edition
|
Tibor (2001)
|
29
|
|
2009 Electronic Inventory
|
CNPS (2019)
|
22
|
References Cited
California Native Plant Society, Rare Plant Program. 2019.
Inventory of Rare and Endangered Plants of California (online edition, v8-03
0.39). Website http://www.rareplants.cnps.org [accessed 13 June 2019].
Center for Plant Conservation (1990). Centre for plant
conservation data for North American plants database. CPC, Centre for plant
conservation.
Humphreys A.M., R. Govaerts, S.Z. Ficinski, E.N. Lughadha
and M.S. Vorontsova 2019. Global dataset
shows geography and life form predict modern plant extinction and rediscovery Nature Ecology & Evolution. https://doi.org/10.1038/s41559-019-0906-2
Kartesz, J.T. (1994) A synonymized checklist of the vascular
flora of the United States, Canada, and Greenland. 2nd edition. 2 vols. Timber
Press, Portland.
Ledford, H. 2019. Global
plant extinctions mapped, Nature
570:148-149.
Preston, F. W. 1948. The commonness, and rarity, of species.
Ecology 29(3): 254-283.
Skinner, M.W. and B.M. Pavlick. 1994. Tibor, D. [ed.] 2001.
Inventory of Rare and Endangered Plants of California, fifth
edition. California Native Plant
Society, Sacramento, CA.
Smith, J.P. Jr., R.J. Cole, J.0. Sawyer, Jr. and W.R. Powell. 1980. Inventory of Rare and Endangered Plants
of California, second edition. California
Native Plant Society, Sacramento, CA.
Smith, J.P. Jr. and R. York.
1984. Inventory of Rare and Endangered Plants of California, third
edition. California Native Plant
Society, Sacramento, CA.
Smith, J.P. Jr. and K. Berg.
1988. Inventory of Rare and Endangered Plants of California, fourth
edition. California Native Plant
Society, Sacramento, CA.
Tibor, D. [ed.]
2001. Inventory of Rare and Endangered
Plants of California, sixth edition. California
Native Plant Society, Sacramento, CA.
Note:
Humphreys et al (2019) Supplemental Data 1 lists Atriplex tularensis as rediscovered, which is incorrectl.
