Saturday, September 13, 2008

Carex atherodes in the central Sierra Nevada

Occasionally and often unexpectedly while botanizing, one finds a plant quite out of range: a plant seemingly allochthonous as to place. I made just such a discovery on September 10, 2008 in the vicinity of Mono Hot Springs, Fresno County.

Carex atherodes Spreng. was collected in Tule Lake, a named lake situated in the Ansel Adams Wilderness, Sierra National Forest, at an elevation of 6,780 feet (2066 meters).

Tule Lake is not hard to access: a short hike on a good signed trail from the trailhead near the hot springs resort passes through a maze of rounded granitic domes and large old-growth Jeffrey Pines for a little over a mile and your there.
Tule Lake is named because the lake is fringed by a marsh of tule (Schenoplectus acutus var. occidentalis), a vegetation condition found at several other lakes in the Mono Hot Springs vicinity (including Dorris Lake).

Tule Lake at Mono Hot Springs is not to be confused with Tule Lake above Florence Lake: that is, there are two lakes in the watershed of the South Fork San Joaquin River with this name [I also visited the other Tule Lake, finding new occurrences of Dulichium arundinaceum and Carex buxbaumii there, the latter the southerly geographic limit]

Tule Lake is fairly deep: the aquatics on the fringe of the lake are Nuphar, Myriophyllum, Potamogeton, Elodea and a Nitella. The lake water surface elevation on the date of my visit was down, owing to the dry years previous: based on the ordinary high water mark seen on the massive dome that forms the southern side of the lake, the water level can be 120 cm higher. At high water, the tule marsh would be in about a meter of water early in the growing season.

The easterly third of Tule Lake is a flat basin bordered by forest, and punctuated by two small granite islands, and is vegetated entirely by three species: tule, Polygonum ampibium, and several large clones of Carex atherodes. When I found the C. atherodes I recognized that it was new to the Sierra Nevada, because of the novel growth form (at least novel for Sierran sedges): the plants have a tall stem (technically, not a culm?) which is topped by an aggregation of leaves, much like a miniature palm might appear from a distance.

The entire population of Carex atherodes at Tule Lake is vegetative: no flowering culms were observed. The marsh was dry such that I could walk (not wade) through the tule swamp throughout the entire population, but could find no flowers. The Ohio DNR fact sheet for this species makes the same statement: “often remains vegetative in less than optimal habitats”

Reznicek & Catling’s 2002 FNA treatment of Carex Section Carex describe Carex atherodes as “ forms large clones and can tolerate deeper water than most Carex“ and that was certainly the case at Tule Lake. The area where the plants occur could be characterized as one large clone covering ca. 20 acres or so, or perhaps several discrete clones over that area. In fact, the blue line lake outline as shown on the USGS topographic map is the area of the lake on September 10th, the mapped flat east of the lake where the wording “Tule Lake” is printed on the map is the site of the C. atherodes clone.

The chemistry of Tule Lake and the lakes adjacent to it were odd: all here somewhat mineralized, with high conductivity and high pH. Tule Lake itself had a conductivity of 250 microSiemens and a pH of 8.5 (extrapolating, a Ca concentration on the order of 1500 ppm). Data from releves in Wisconsin characterize C. atherodes as being calcareous and saline (their WMs92 association, where I note Polygonum amphibium was also a frequent associate). Fernald in Gray’s Manual describes the habitat of Carex atherodes as calcareous meadows, which is suggestive of Tule Lake

Although Carex atherodes is widely distributed in North America, it not common in many states (rare status in Ohio, Maine, Illinois [4 counties], Virginia [one site, potentially extirpated] Wyoming [4 stations], Missouri, Pennsylvania etc. Wheat sedge [atherodes , Greek‘ear of wheat’] is a rare plant in California.

In California, vouchers of Carex atherodes have been collected at three stations: two sites in the Tule Lake (again, tule!) basin of Modoc County near Alturas; in Ash Valley, Lassen County, and in what would appear from the label data in a similarly odd mountain setting: Canyon Creek lakes in the Trinity Alps. The Ash Valley site was heretofore the southerly distributional limit, but the Tule Lake (Fresno County) site reported herein is 275 miles (440 km) south of the previous southerly station in California. However, vouchers of C. atherodes from Arizona are documented as far south as the Fort Apache Indian Reservation (Navajo County) at 33.9N. Carex atherodes is reported from Elko County, in near northeastern Nevada. Carex atherodes is an important forage plant for Bison (cf. Oecologia (2003) 134:219–227); there is the C. atherodes Seasonally Flooded Herbaceous Alliance of South Dakota.

One can ponder whence Carex atherodes came to Tule Lake in the central Sierra? The most attractive notion is long distance dispersal via some extraordinarily constipated duck (Northern Prairie Wildlife Research Center webpage “The achenes are eaten by waterfowl”; apparently important to Redhed in Iowa). However, my pondering also includes the notion that C. atherodes was probably once more common in the arid west at the height of the Pleistocene, and outlier occurrences are in part relictual. Could in fact had C. atherodes occurred in the Great Valley before our marshes there were eliminated?

Thursday, July 31, 2008

Fen at Pat Yore Flat, Nevada County

the fen is a shrubby site (above)

the little white heads of R. alba are distinctive (below)

Pat Yore Flat

Fens are odd, azonal, habitats that are in California known to support a variety of circumpolar, northern Hemisphere oroboreal (sensu Webber) taxa. Our fens are the southerly stragglers barely hanging on, remnant of Pleistocene abundance. In general, fens and bogs in the Sierra have not enjoyed much direct attention from botanists. Most sites are not described in detail. The most comprehensive fen overview is David Cooper’s report “Fens of the Sierra Nevada” which is mandatory reading on the topic.

Because Cooper & Wolf (2004) had reported Rhynchospora alba (CNPS List 2) from this location, and because there were no Consortium or CNDDB records for of R. alba from this location (including the pending file) I paid a visit.

Pat Yore Flat is located right along Forest Road 50, which I accessed via Highway 20 through Washington, thence up Forest Road 31, Nevada County (39.41409/-120.70702, T18N R11E Section 23; 6100 ft. Graniteville USGS quadrangle). The origin of the name is uncertain (Durham 2000 “Place Names of California’s Gold Country” ; Gudde 1969).

The flat is situate in the South Fork Yuba River drainage; the entire vicinity is mapped as granitic rocks. The flat is a gently sloping surface inclined about 5% facing southerly. The fen at this site is extensive, covering 100 ha or so, with general spring/seep discharge over an extensive area. I did not spend sufficient time to explore the entire fen.

Like an old fashioned waterbed, peat filled openings of the fen have a ‘quaking’ character, which is more typical of bogs formed via primary succession in lakes (i.e. Grass Lake, Luther Pass or Little Willow Lake, Lassen Volcanic NP). The depth and age of the peat deposits in this fen are a curiosity: are they Tioga stage (glacial) in age (i.e. >14 KYA?). A coring study is suggested, because I assume the quaking nature of the site indicated deep peat deposits which might yield a valuable chronology.

The water discharge into the fen is relatively sweet (I got a conductivity of only 10┬ÁS), and the bog is moderately acid (a hand held grab sample pH was low as 5.5, but did not control for the low-ionic water problem). Bogs are pH <5>