BEN
BOTANICAL ELECTRONIC NEWS
ISSN 1188-603X

No. 222 April 28, 1999 aceska@victoria.tc.ca Victoria, B.C.
Dr. A. Ceska, P.O.Box 8546, Victoria, B.C. Canada V8W 3S2

MEADOWLARK FESTIVAL, OKANAGAN VALLEY - B.C., MAY 21-24

From: Lisa Scott [lscott@vip.net]

On May 21-24 join us in celebrating spring and experience the unique landscapes of the south Okanagan and lower Similkameen Valleys during the second annual Meadowlark Festival. The Meadowlark Festival was initiated by the Okanagan Similkameen Conservation Alliance to encourage people of all ages to experience, discover and explore our natural environment. The Okanagan-Similkameen hosts a rare mosaic of natural habitats, among them is one of Canada's most endangered ecosystems - the hot, dry shrub-grasslands.

Festival events range from lively slide shows and discussions on nature and conservation topics, to canoe trips, horseback riding, a photography workshop, and a wide variety of bird and wildflower explorations.

Events occur in a wide variety of locations throughout the Okanagan-Similkameen and involve some of BC's and Canada's leading experts, including Mark Brigham, Geoff Scudder, Dick Cannings, Terry McIntosh and Bill Barlee. You can learn to identify bird species by their songs with John Neville, who produced the CD 'Bird Songs of the Okanagan Valley'. And join other festival participants during the banquet and silent auction on Saturday evening, and be entertained by a stunning audio-visual presentation by Graham Osborne, hailed as one of BC's and Canada's best photographers.

The price for taking part in the festival has been kept very low to encourage broad public involvement, but pre-registration is required as space for many events is limited, to protect the fragile areas we will visit. The aim is for people to have a wonderful weekend outdoors, to learn more about our diversity of wildlife and to work together to conserve our valuable wildlife habitat.

For further information and to register for events contact the Meadowlark office:

HELP TO TRACK THE DISTRIBUTION OF GORSE (ULEX EUROPAEUS) IN B.C.

Gorse (Ulex europaeus) is a dense spiny shrub that invades the Pacific Northwest. The Pacific Forestry Centre in Victoria, B.C. is currently documenting any sightings of this invasive shrub. Be careful not to confuse it with broom (Cytisus scoparius). At this time of year, they both have yellow pea-like flowers. Upon closer inspection you will notice large sharp spines on gorse. The spines make access to colonized areas almost impossible, and the stems contain oils which create a fire hazard.

Have you seen gorse in your area?

Please contact:

PLANT DIVERSITY IN BARKLEY SOUND [Part 3 of 3]

From: Martin L. Cody [mlcody@ucla.edu]

POPULATION TURNOVER, ISLAND ADAPTATION AND EVOLUTION

Incidence functions tell only part of the story, and in particular omit the dynamics. With repeated censuses of specific islands, many instances of colonization and extinction have been uncovered, allowing measurement of population turnover rates; these can be calculated as the proportion of islands which are different in name, because of yearly colonization of "new" islands and extinction on "old" islands. In the composites, values range from a low of 0.066 (in Achillea millefolium, which is very persistent) to a high of 0.974 (in Anaphalis margaritacea, in which populations wink in and out very rapidly). Of course most trees and shrubs are long-term persistent, but not necessarily so on the smaller islands. Species with general similarity in incidence functions, e.g. Anaphalis and Lactuca muralis, can differ dramatically in turnover rates.

For adaptation and evolution to occur in situ on islands, reasonably persistent populations are prerequisite; we have shown (Cody & Overton 1996) that strong selection for reduced dispersal, in terms of lower ratios of pappus to achene volume, is detectable in island Lactuca populations within a decade after initial colonization. In other candidates for such evolution, it is precluded in Hypochaeris radicata because of low turnover rates (and therefore very few newly initiated island populations to sample), and in Senecio vulgaris by a combination of few persistent populations and a nonsignificant relationship between propagule morphology and drop time (i.e. lack of correlation between morphology and dispersal potential).

A second interesting example of island evolution is provided by the ubiquitous fern Polypodium scouleri, in which frond size, thickness, and degree of dissection varies conspicuously with the size of the island the population occupies. On small, dry islands the fronds are short, thick, and possess as few as three pinnae, but on larger islands and in wetter or more shaded sites fronds are long, thinner, and have perhaps 8 times as many pinnae. In fact this species is a useful bioassay of the local island climates. REFERENCES

Cody, M.L. 1992a.
Plant species turnover and microevolution on continental islands off NW and SW North America. Amer. J. Bot. 79(6) Suppl: 50.
Cody, M.L. 1992b.
Some theoretical and empirical aspects of habitat fragmentation. J Keeley (ed.) Proc. So. Calif. Acad. Sci. 1991 Symposium, Occidental College.
Cody, M. L. 1999.
Assembly rules in bird and plant communities. Ch. XX in Keddy, P., & E. Wieher (eds), The Search for Assembly Rules in Ecological Communities. In press, Cambridge Univ. Press.
Cody, M. L., & J. M. Overton. 1996.
Short-term evolution of reduced dispersal in island plant populations. J. Ecol. 84(1): 53-61.
Cody, W. J., & D. M. Britton. 1989.
Ferns and Fern Allies of British Columbia. Publ. Research Branch, Agriculture Canada. Ottawa.
Dawson, A. G. 1992.
Ice Age Earth: Late Quaternary Geology and Climate. Routledge, London & NY.
Diamond, J. M. 1975.
Assembly of species communities. pp. 342-444 in M. L. Cody & J. M. Diamond (eds.), Ecology and Evolution of Communities, Belknap Press of Harvard Univ. Press, Cambridge, MA.
Friele, P. A., & I. Hutchinson. 1993.
Holocene sea-level changes on the central west coast of Vancouver Island, British Columbia. Canad. J. Earth Sci. 30: 832-840.
Hitchcock, C.L., & A. Cronquist. 1973.
Flora of the Pacific Northwest. Univ. WA Press, Seattle.
Klinka, K., V.J. Krajina, A. Ceska, & A.M. Scagel. 1989.
Indicator Plants of Coastal British Columbia. Univ. Brit. Columbia Press, Vancouver.
Muller, J.E. 1983.
The Tertiary Olympic Terrane, SW Vancouver Island and NW Washington. Field Trip #12, Geol. Assn. Canad. (Victoria, BC).
Pojar, J. & A. MacKinnon. 1994.
Plants of Coastal British Columbia. B.C. Ministry of Forests and Lone Pine Publ., Vancouver, BC.
Stebbins, G. L. 1950.
Variation and Evolution in Plants. Columbia Univ. Press, NY.
Yorath, C. J. 1995.
The Geology of southern Vancouver Island. Orca Bk. Publ., Victoria, BC.

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