| BEN |
| BOTANICAL ELECTRONIC NEWS |
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| ISSN 1188-603X |
| No. 234 October 25, 1999 | aceska@freenet.victoria.tc.ca | Victoria, B.C. |
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(Abstract of the paper presented at the symposium on "Vegetation Classification and Mapping in the Rocky Mountains," Glacier National Park, Montana, 29 June - 2 July 1999)
Phytosociology (Braun-Blanquet sampling) is not totally unlike timber cruising -- it provides a means for extensive vegetation sampling, covering large areas quickly without having to do measurements in the field or statistics afterward. It consists of three steps: field sampling, classification (clustering of similar samples), and naming (associations and higher levels). Not all steps are necessary, depending on the purpose. Although developed in Europe during the first half of this century, concepts of phytosociology (especially the sampling methodology) have been found very useful in a US context, especially in the recent large-area inventories of The Nature Conservancy and the various state Natural Heritage Programs.
The Braun-Blanquet field methodology provides a standardized, full-floristic, three-dimensional stand description called a releve (composition, structure, and abundance), which is understood by vegetation scientists all over the world. Classification can be performed by various computerized clustering algorithms, some of which (e.g. TURBOVEG) have been used for very complete national inventories and classifications, as recently in South Africa. The final products, associations and related vegetation units, are the basic units of most other approaches and are quite compatible, for example, with the associations in the US National Vegetation Classification.
The only real prerequisite, relatively complete knowledge of the local flora, can be overcome by working with a good local botanist. Large-area applications in North America include ongoing forest inventories in eastern and western Canada, a 1988-90 inventory throughout eastern North America, and recent classifications of boreal and western North America by two Spanish groups.
On the last weekend in September, a small but keen group of thirteen lichen enthusiasts gathered at the home of Tevor Goward for a workshop on the lichen genus Cladonia. We were a varied bunch with a similar goal: to gain an understanding of the taxonomy of Cladonia, as well as some insight into the ecology of this complex genus.
The weekend began on Friday evening with an informal discussion about lichens. The good company and cozy atmosphere sparked intriguing conversation. Although several topics were covered, one takes home message was that in order to begin to understand a lichen we must view the species interacting within its natural landscape as well as its individual characteristics and functions.
Saturday morning we dove into Cladonia taxonomy! Armed with Trevor's new book "The Lichens of British Columbia, Illustrated Keys Part 2 - Fruticose Species" and supplied with numerous Cladonia samples, we began working our way through the keys. Although approximately 69 Cladonia species exist in B.C., we focused on the 38 which occur in the southern interior. Instruction was also given on the use of chemical spot tests and ultraviolet light tests for identifying particular species. Upon trying to understand color differences between Cladonia species, we witnessed the birth of a new color - usnic! This color was described by Trevor as yellowish-green, but may be seen as greenish-yellow to some.
By combining our patience and helpful hints from Trevor, we were successful in identifying many species. However, we also became aware of the extremely varied forms a particular species may take. These tricky samples illustrated the complexities of this feared genus. In the afternoon we took a well-deserved break to visit some of the sites in Wells Grey Provincial Park, and then reconvened to discover more Cladonia species into the early evening hours. Sunday morning we continued keying samples, and again ventured outside in the afternoon. By this time I think we had accomplished a lot and gained respect for what we had yet to learn. The weekend was a definite success.
I would like to thank Trevor Goward for hosting the workshop and sharing his home, time, and wisdom. Thank you Patrick Williston for your effort in organizing another great lichen workshop. l would also like to thank the participants of the workshop for their friendly enthusiasm. I hope to see you again!
When the original edition was published, the identification keys were reprinted in a separate soft-cover booklet. This booklet is still (or again?) available as