|BOTANICAL ELECTRONIC NEWS|
Dr. A. Ceska, P.O.Box 8546, Victoria, B.C. Canada V8W 3S2
PLANT DIVERSITY IN BARKLEY SOUND [Part 2 of 3]
From: Martin L. Cody [email@example.com]
DISPERSAL AND COLONIZATION
On smaller islands where both colonization and extinction both play a role, there is much lower predictability in species numbers, with area (e.g. r**2 = 0.3-0.5). This is expected if colonization rates are isolation-specific, with a minor role of island size via a "target" effect. Four common dispersal syndromes are represented on the islands:
- FERNS ARE DISPERSED VIA DUST-LIKE HAPLOID SPORES that give rise to a tiny short-lived gametophyte which produces antheridia or archegonia or both; after gametic union, it is replaced by the often large and long-lived diploid sporophyte whose sori in turn are the source of a further generation of spores (e.g.Stebbins 1950). To date 9 species have been encountered on the islands, but several others are possibilities (Cody [W.J.] & Britton 1989). Of the eight focal species, half are typical of shaded and moist forest-floor sites, but some are rather more habitat specific; one (Polypodium scouleri) occurs on coastal rocks, another (Adiantum pedatum) on damp interior rocks, bracken (Pteridium aquilinum) prefers dry, sunny banks, and a fourth (Polypodium glycyrhiza), perennial but with annual fronds, is largely epiphytic on tree trunks. All of the fern species have rather regular and sigmoidal incidence functions (plots of proportion of islands occupied versus island size) well fitted by logistic regression, but island size at which incidence begins to decline varies among species, and in particular only those species with high leaf-specific weight and minimal frond dissection (e.g., P. scouleri) persist on the smaller islands.
- At the opposite end of the vegetation gradient from the forest ferns are PLANTS RESTRICTED TO THE SHORELINE ROCKS AND BEACHES, of which there are some 30 characteristic species (Cody 1998). Examples are Atriplex patula (Chenopodiaceae), Honkenya peploides and Sagina crassicaulis (Caryophyllaceae), Triglochin maritimum (Juncaginaceae), and four grasses (Poaceae): Festuca rubra, Hordeum brachyantherum, Poa annua, Puccinnellia pumila. They differ in habitat preference and are representative of the range of shoreline sites; most are of wide Holarctic distribution, and annual and perennial species are about equally represented in the guild. Most of these shoreline species disperse by floating propagules, but in the two dry-rock grasses wind, or possibly animals such as shoreline birds may effect dispersal ("ectozoochory"), though they are but modestly awned; of the two, Festuca is rhizomatous and Hordeum is not. Incidence functions for some shoreline species are reasonably monotonic with area, but others are not.
- A third guild is WOODY SHRUBS that occupy the ecotone between the forest and the shoreline. There is a choice from perhaps two dozen species for this category, and examples include four species of Rosaceae (Rosa, Rubus), 2 of Caprifoliaceae (Lonicera, Sambucus), Grossulariaceae (Ribes) and several Ericaceae (Arctostaphylos, Gaultheria, Vaccinium, Menziesia), among many others of narrower distribution (e.g. in Rosaceae, Amelanchier, Aruncus, Crategus, Holodiscus, Physocarpus, Sorbus, Spiraea). These species produce variously succulent berries and disperse via endochory, using the locally common thrushes (Turdus migratorius, Ixoreus naevius, Catharus ustulatus, C. guttatus) and crows (Corvus) as dispersal agents. The fruits in this guild span a range of sizes, colors, and maturation phenologies, as in the three Rubus species which differ conspicuously in timing and color of mature fruit: R. spectabilis matures early (mid-June) with orange fruit, R. parviflorus 2-3 weeks later with red fruit, and R. ursinus later still with blackish fruit (Cody unpubl). Two other Rubus spp., the alien R. procerus [=R. armeniacus] and R. laciniatus, are rare on the islands. Incidence functions for berry-producing shrubs decline with island area but at different rates in different species. For examples, Lonicera shows no effects of increased isolation, while the effects are strong in Sambucus, which has much reduced incidence on distant islands. The three Rubus species are ranked in decreasing incidence spectabilis-parviflorus-ursinus, in all cases with lower incidence on more distant islands; habitat availability among these edge shrubs is not likely to vary over island isolation, indicating perhaps a role for differential dispersal and colonization.
- Between the shoreline and the forest edge is a zone a few meters wide where WEEDY HERBACEOUS PLANTS form a nearly-continuous cover. This is the largest component of the flora (ca. 100 species), with representatives of such families as Apiaceae, Brassicaceae, Onagraceae, Polygonaceae, and species of Asteraceae are especially common. Studies have focussed on the latter family; most are short-lived perennials, some are biennials and some annual. Some species have distinct substrate and exposure preferences, and most are anemochorous and disperse via achenes borne on a parachute-like pappus. However, the most widely distributed species on these islands, Achillea millefolia, matures later in the season that do others in the guild and apparently disperses as an ectozoochore when migrating shorelbirds fill the Sound in late August. Two other composite species, Anaphalis and Aster, also have non-anemochorous (and non-obvious) dispersal means. Incidence functions generally decline with decreasing island size, but in widely variable fashion. At the extremes, it is gradual in Achillea and precipitous in Sonchus. Incidence in the three non-anemochorous species (Achillea, Anaphalis, Aster) show little or no effect of island isolation, but in the anemochores all show reduced incidence on the more distant islands in line with expectations of declining colonization rates with increasing distance from source. The variety of incidence functions is further extended by other species such as Matricaria matricaroides, which occurs only on very small islands (near and far), and is a good example of a supertramp (Diamond 1975).
[Conclusion in BEN # 222]
VEGETATION CLASSIFICATION AND MAPPING IN THE ROCKY MOUNTAINS SYMPOSIUM AND FIELD EXCURSION
FIRST PRE-REGISTRATION NOTICE
Sponsored by the International Association of Vegetation Science, North American Chapter, Glacier National Park, and the Kootenai National Forest Botany/Ecology Programme.
Symposium - 29-30 June 1999 - Kalispell, Montana Excursion - 1-2 July 1999
In recent years there has been a flurry of activity in the arena of vegetation classification and vegetation mapping, ranging from the introduction of a new vegetation classification system by the Federal Geographic Data Commission and The Nature Conservancy to advances being made in on-the-ground applications, from Alaska to Colorado. Much of this work reflects an ongoing effort to establish baseline data about vegetation, departing from the past emphasis on site potential and concentrating on the existing vegetation in direct relationship to processes and environment. Unfortunately, much of this work is not very well known. Even many vegetation scientists do not know about work being carried out in other areas, and the users of vegetation classifications have been confused about the relationship of the newer vegetation classifications to habitat types and other vegetation work done up until the present.
Against this background, vegetation scientists from across the Rocky Mountains and Pacific Northwest have been invited to present recent work on vegetation classification at a symposium in Kalispell, Montana on the 29th and 30th of June, 1999. The objectives of the meeting are to facilitate communication amongst vegetation scientists, familiarize natural resource managers with the existing vegetation classification systems as well as recent developments in vegetation science in our region, and solicit feedback from users on the ground, in a structured but informal setting. The target audience includes vegetation ecologists, foresters, botanists, wildlife biologists and other professionals who use vegetation classifications on a daily basis. We hope this exchange will shed light on some of the following general topics:
- do new directives for natural resource management require new perspectives of vegetation?
- taking stock of disturbance-dependent vegetation: do we have an information void?
- acquiring the information needed in natural resource planning (NEPA, Forest Practices Code)
Applying classifications on the ground:
- classification of all vegetation: aims and methods of phytosociology
- field methods and table sorting: how results are arrived at
- syntaxonomy: bringing different vegetation classification efforts "onto the same page''
- relationship of phytosociology to habitat typing
- the National Vegetation Classification System
- landscape vegetation classification: aggregating vegetation units at larger scales
- state of knowledge: what recent classifications have been completed in the west?
- potential natural vegetation: new thoughts on old ideas
- how are vegetation classifications used in resource management?
- vegetation inventory; what vegetation attributes should be routinely collected for conservation and management purposes?
- how can baseline existing vegetation inventory be achieved by land management agencies with limited budgets?
- vegetation mapping; integration of field inventory and GIS techniques
- where do we need to go from here?
Two days of presentations will be followed by two days of field excursions (limited to 25 people). On the 1st of July, Christian Damm will show us alpine tundra vegetation in Glacier National Park which he recently classified using Braun-Blanquet methods, while on the second day (2 July) we will examine forest vegetation on the Kootenai National Forest, recently classified by Dan Leavell on the basis of existing vegetation. We will discuss how Glacier National Park and the Forest Service, respectively, will be using these classifications, and how they could change the way we view vegetation in these different environments.
In the course of the symposium, we will also learn about work recently completed in Colorado, Alaska, British Columbia, and other parts of the west. We will have a chance to pose our questions to a panel of senior vegetation scientists including members of the Ecological Society of America Vegetation Classification Panel.
The organizing committee needs to get initial feedback on the number of people interested in attending the symposium. If you are intending to attend this meeting, please send an e-mail to: Jack Triepke, Kootenai National Forest, firstname.lastname@example.org (IBM: jtriepke/r1,kootenai). Your name will be added to a mailing list to receive future mailings about this symposium.
A DRAFT AGENDA listing the scheduled presentations will be forthcoming and will be mailed out to those who respond to this posting. Individuals interested in presenting posters or scheduling brief presentations, please contact Toby Spribille at 406.882.4451 or e-mail: email@example.com as soon as possible. Formal registration in the symposium will carry a modest fee, not expected to exceed US$60.00 per person.
WORLD WEEDS DATABASE ON CD-ROM
From: "P. Bacon" [firstname.lastname@example.org]
The World Weeds Database is based on the information contained in the book "A Geographical Atlas of World Weeds" by Leroy Holm, Juan V. Pancho, James P. Herberger and Donald L. Plucknett, which was published in 1979.
The book is a comprehensive list of weed species of the world and their distribution after a research-work of ten years. Even though it does not include all the species for any geographical region it is a good information source for workers and scientists.
The purpose of the database is to make it possible to retrieve valuable information from this book and make it available for foresters or any other person who might be interested in knowing the distribution of the most common and worst weeds. The World Weeds Database displays information on nearly 7000 weed species around the world according of its rank of importance. The database contains Genus, Family and Species names as well as taxonomic authorities.
This database is a development of work originally done in 1994 and 1995, supported by The Natural Resources Institute, Long Ashton Research Station, The Forestry Research Program (OFI) and the UK Overseas Development Administration.
We've now got this copied to CD-ROM. Full spec can be viewed at:
Copies available from here at 27 British Pounds or equivalent. Please pass this message on to anyone who might be interested.
Dr. P. Bacon, Oxford Forestry Institute
Department of Plant Sciences, University of Oxford
South Parks Road, Oxford OX2 3RB - UK
fax: 01865 271036 phone: 01865 271035