EPOW - Ecology Picture of the Week

Explanation:   This pretty spray of thalli is a reindeer lichen, growing in the McKenzie Mountains of north-central British Columbia, Canada.  Reindeer lichens constitute a group of several species of genus Cladina (previously part of the genus Cladonia).  

This one is Cladina mitis which can be distinguished from the very similar species Cladina arbuscula only with a chemical test ... or, for the experienced lichenologist, by a taste test.  Cladina mitis has a mild flavor ("mitis" means "mild"), whereas Cladina arbuscula has a bitter taste from fumarprotocetraric acid.

Reindeer lichens are common in open lodgepole pine, jackpine, and other montane and northern latitude forests, and they blanket parts of the arctic tundra.  They are the main winter food of caribou (which are called reindeer in Europe).  Reindeer lichen provide poor nutrition, grow slowly, and quickly give up their riches to nibbling ungulates, which may be one reason why caribou herds migrate.  In moving about, the caribou likely also help disperse the lichen -- a symbiotic relationship.  However, if caribou are prevented from moving and end up overgrazing the lichen cover, the result can be a change toward cover by small dwarf shrubs, bare soil, and minute-cup lichens (Cladonia spp.), reducing natural regeneration of the native vegetation.

People use reindeer lichens in many ways.  Lapps harvest reindeer lichens for their reindeer herds.  Some Inuit consume half-digested lichens taken from the stomachs of caribou killed in winter.  Reindeer lichens also are used as miniature trees in architectural models.  Extracts are used for perfume bases and antibiotics.  

Cladina mitis is sensitive to air quality and can serve as a good indicator of sulphur dioxide from acid rain and levels of atmospheric ozone, serving as an "early warning" of impending decline of overall air quality.

The name "cladina" is Latin for "small branches," which describes the shrub-like growth form of this common lichen. 

Information:
     der Herder, M., M.-M. Kytöviita, and P. Niemelä. 2003. Growth of reindeer lichens and effects of reindeer grazing on ground cover vegetation in a Scots pine forest and a subarctic heathland in Finnish Lapland. Ecography 26(1):3-12.
     Matthews, D. 1988. Cascade-Olympic natural history. Raven Editions and Portland Audubon Society, Portland, Oregon. 625 pp pp.
     McCune, B., and L. Geiser. 1997. Macrolichens of the Pacific Northwest. Oregon State University Press, Corvallis, Oregon. 386 pp.
     Pojar, J., and A. MacKinnon. 1994. Plants of coastal British Columbia including Washington, Oregon & Alaska. Lone Pine Publishing, Vancouver, B.C. 527 pp.
     Vitt, D., J. Marsh, and R. Bovey. 1988. Mosses lichens & ferns of northwest North America. Lone Pine Publishing, Canada. 296 pp.