Part 1 covered the hike, but we didn’t touch at all upon the lichens on Mt. Whitney! So let’s do that here.
Firstly, you might be wondering – what’s the history of lichen collections of Mt. Whitney? Two words: its limited.
Here’s the stats:
Date Collector(s) taxa specimens
15 Aug 1904 J.D. Culbertson & C.F. Baker 5 8
1959? R.H. Torrey 1 1
11 July 1955 H.A. Imshaug 13 43
30 April 1986 S. Souney 3 3
2006? M. Westberg 1 5
Source: CNALH 2016
For those of you new to this project, the idea is to resurvey the sites that lichenologist Henry Imshaug surveyed in the 1950’s, see if the flora has changed, and if so, pick out some candidate species for further research into climate change biomonitoring using lichens.
You’ll notice that although Imshaug collected 43 specimens, there’s only 13 reported taxa (e.g. species). Some of those specimens are duplicates, but others remain unidentified. And that’s not for lack of effort on Imshaug’s part: the taxonomy of many crustose lichen groups were not yet worked out back in 1955. Rest assured, there’s still problem groups today, but for the most part we’ve got a leg up that Imshaug didn’t have back then.
So, you might be wondering, did we find everything that Imshaug found? From what we currently know of Imshaug’s identified collections, we’re only missing one species: Megaspora verrucosa. And we found a number of macrospecies that Imshaug did not report (Imshaug 1957). These species include Physcia dubia, Rhizoplaca melanopthalma, and Xanthomendoza galericulata. Could these species be extending their range upslope, increasing in elevation, or were these species present back in 1955, but Imshaug simply didn’t collect them?
It’s important to note that Imshaug conducted his survey on Mt. Whitney as part of a day hike, and continued on to Kearsarge Pass the next day, followed the next day by Bishop Pass. He was moving and working fast, and working alone as far as we know – so perhaps he overlooked these species. Or perhaps these species are truly expanding their range.
One way to discern whether the establishment of species such as Rhizoplaca melanopthalma is new on Mt. Whitney and other similarly high peaks in the southern High Sierras would be to conduct a few transects from low alpine elevation to high alpine elevation, and simply measure the largest average thalli at each interval. If the size of the average largest thalli decreases with increasing elevation, an inverse relationship, that would be a strong indication that the species is newly establishing at higher elevations. It’s a non-invasive method, would requires minor training, and could be a fun citizen science project. Anyone out there interested?
And now for the lichen photos…
Imshaug, H. A. (1957). Alpine lichens of western United States and adjacent Canada I. The macrolichens. The Bryologist, 60(3), 177-272.
CNALH. (2016). Consortium of North American Lichen Herbaria.
Knudsen, K. (2007). “Pleopsidium” in The Lichen Flora of the Greater Sonoran Region Vol. 3 by Nash