In 2015, Yosemite National Park moved to acquire 415 acres at Ackerson Meadow, adjacent to the western Park boundary in Tuolumne County (in the vicinity of Mather and the road to Hetch Hetchy). This acquisition was facilitated by a donation of the owners to the Trust for Public Land, and then by conveyance to the National Park Service.
Ackerson Meadow is a rare feature in the Sierra Nevada: a mid elevation (~4000 feet) non-forested setting supporting wet to dry meadows. Ordinarily, such an addition to the Park ought to add considerably to the documented Yosemite National Park flora, being that the western Park boundary generally excludes much low to mid-elevation settings of the western slope of the Sierra.
The region of Ackerson Meadow was part of Yosemite National Park in 1890 (act of Congress, October 1st 1890). It was then removed, and any Public land in the vicinity was conveyed to the Forest Service by Congress acting on June 11, 1906. By the time that John Muir has successfully argued for an expanded Yosemite in 1890, the land in the vicinity of Ackerson Meadow had been granted to James F. Ackerson in 1882 and 1884. Portions of the Ackerson Meadow system are now managed by two agencies and under two administrative directives: about 200 acres of the meadow system remains within the Stanislaus National Forest.
Generally, the flora of the Yosemite region is well documented (Taylor 2010, Baldwin et al. 2017). The four counties flanking Yosemite are rank about the 90th percentile for the western U.S. (Taylor 2014). In 2014, Yosemite National Park raked in the 97th percentile for specimen density. My analysis, based on records of herbarium specimens in the Consortium of California Herbaria, the acquisition adds only 4 potential new vascular plant records for the Park.
Species Added to YNP
Eryngium vaseyi var. vallicola (Apiaceae, JEPS101766) – this vernal pool coyote thistle is perhaps a new species: Preston et al (2012) stated :”plants keying here from cSNH (Tuolumne Co.) may be an undescribed taxon.” Obviously, this possibility alone is worthy of funding for additional study.
Erythranthe utahensis (Phrymaceae) – a single collection is attributed to Ackerson Meadow (R. K. Vickery 191, August 26, 1949. UT). The record was accepted by Nesom (2012), with the provision “have the taller habit of E. utahensis but with fewer flowers as in E. corallina and an apparently intermediate vesture”. Obviously, this possibility alone is worthy of funding for additional study: E. utahensis is a CNPS rare plant, List 2B.1
Polygonum polygaloides ssp. confertiflorum (Polygonaceae, JEPS96724) – an annual of open dry sites that are wet to saturated in spring. This location is the southerly reported station for this taxon.
Hosackia pinnata (Fabaceae, JEPS100871) – This wetland perennial also reaches its southerly geographic distribution in the Yosemite region. The more common sister species in Yosemite, Hosackia oblongifolia var. oblongifolia, has been collected ~50 times in the Park.
The purpose of this post is to emphasize that a detailed floristic inventory of the acquisition, using rigorous methodology (Groom & Whild 2017), is needed. The Yosemite Conservancy has undertaken an initial inventory of Ackerson Meadow: extensive, vouchered floristic inventory over a period of several years will be required to ascertain the exact value of this addition to Yosemite NP.
Groom, Q. J. and S.J. Whild. 2017. Characterization of false-positive observations in botanical surveys. PeerJ 5:e3324; DOI 10.7717/peerj.3324
Nesom, G. 2012. Taxonomy of Erythranthe sect. Simiola (Phrymaceae) in the USA and Mexico. Phytoneuron 40: 1–123. Published 16 May 2012. ISSN 2153 733X Corrections to Map 9 and Map 15, 21 May 2012
Taylor, D.W. 2014. Large inequalities in herbarium specimen density in the western United States. Phytoneuron 2014-53: 1–8. Published 2 June 2014. ISSN 2153 733X
Taylor, D. W. 2010. Flora of the Yosemite Sierra. Lulu Press, Raleigh, NC. 382 pp. ISBN 780557500529
Baldwin, B.G. et al. 2017. Species richness and endemism in the native flora of California. Amer. J. Bot. 104 (3): 487 – 501, 2017 doi:10.3732/ajb.1600326