|BOTANICAL ELECTRONIC NEWS|
|No. 312 August 4, firstname.lastname@example.org||Victoria, B.C.|
The Canadian Museum of Nature in Ottawa and the Biology Department of the University of Ottawa invite applications for the Canadian Museum of Nature Systematics Professorship, a joint position at the two organizations. The successful candidate will have a tenure-track Assistant Professor position at the University, with 50% of his/her responsibilities at each institution. We seek candidates who have demonstrated excellence in conducting research, and enthusiasm for both formal teaching at the University and for public outreach through the Museum. The University has strengths in cellular and molecular biology, ecology, and physiology, and the Museum in biodiversity, palaeontology, mineral sciences and collections development. The Museum is Canada's national natural history museum offering all of its programs in both English and French, and the University of Ottawa is North America's largest bilingual university. There will be a strong preference for a candidate able to function in both languages.
We seek an applicant with a Ph.D. in botany, plant sciences or biological sciences, with a specialization in plant systematics, preferably in lichenology or lower plants. The applicant must possess practical experience in collections-based research, a proven publication record, and be able to work in both museum and university environments. The candidate will be expected to compete for external funding for his/her research.
Applications should be received by September 31, 2003. The University and the Museum are committed to employment equity and we encourage applications from all qualified individuals. In accordance to Canadian immigration requirements, first priority will be given to Canadian citizens and permanent residents. A complete statement of qualifications is available upon request. Applicants should send a curriculum vitae, a description of future research, a description of teaching and/or public outreach interest and experience, and the names of three individuals willing to furnish letters of reference to: UO-CMN Search Committee, Biology Department, University of Ottawa, Box 450, Station A, Ottawa, Ontario K1N 6N5. For further information, contact: email@example.com or MGRAHAM@mus-nature.ca
A method of weed control in natural areas, developed at Sydney, Australia, by Joan Bradley and her sister, has been so successful a summary of their methods is presented here with the thought that similar endeavors in California would result in better weed control where such methods might be appropriate.
The Bradley method makes practical use of well-known ecological principles. The method consists of hand weeding, without replanting, selected small areas of vegetation in such a manner that after weeding, each area will be promptly re-inhabited and stabilized by the regeneration of native plants.
If the weeding is approached as a conventional gardening operation, in which large areas are cleared and burned or the debris carted away, the effort will fail because large exposed and disturbed areas will become re-colonized by new weeds. The Bradley method urges a naturalist's approach by encouraging the native vegetation to become reestablished. The Bradleys used their method to successfully rid a forty-acre woodland reserve of weeds so that the reserve needed slight attention only once or twice a year, mainly in vulnerable spots such as creek banks, roadsides, and clearings, to be maintained weed-free. They summarize their activities as follows:
"We are regenerating bush with conspicuous success over a total area of about forty acres, and our results are plain to see, both in Ashton Park and on nearby Chowder Head. We have also taken care of the weeds induced by a six-acres "silvicultural" winter burn, and about four or five acres of other fires. We have not overworked at it. We are both over fifty, able-bodied but by no means Amazonian. My sister takes the dog for a walk on most mornings. and I do the same in the afternoons. On these walks we might average, between the two of us, about three-quarters of an hour spent actually pulling up weeds."
"Done in our way, the regeneration of weed-infested bushland is an easy and fascinating part-time occupation. We are still forging ahead, my sister mainly on a dry ridge, myself mainly in a damp gully, faster than we should have thought possible... We hope that this outline of our methods will encourage and help you to do the same."
In undisturbed vegetation, soils are often covered with a litter of decaying plant material. This natural mulch, when present, will permit very few weed seedlings to come through. Since disturbed soil favors the weeds over the natives, and weeding disturbs the soil, all natural litter possible should be replaced over the spots that are weeded. Also, wherever possible, the weeds themselves should be used as a mulch, except that such things as seeds, bulbs, rhizomes or other parts that might sprout should be removed.
Plan of Work
In this sequence the Bradleys designed work for one person to follow, working from the best stand of native vegetation to the worst infestation of weeds. By keeping the sequence always the same, it can be followed by any number of people in any number of places.
The Bradley sisters keep general written records, make periodic surveys, and map the weed infestation. They find it much easier than relying on memory of past infestations. Also, the mapping is useful to show local authorities the progress of the work. Their work has been so successful, and the regenerated native vegetation looks so good, that it is difficult to show people what has been done. Wouldn't it be nice if all our parks and reserves were that weed-free?
At the time of its introduction in 1961, no one could have predicted the detrimental consequences of English cordgrass, Spartina anglica C.E. Hubbard, to the intertidal communities of Puget Sound, Washington. The intent of introducing this nonindigenous marine grass was to stabilize a dike system in the Skagit Valley and provide forage for cattle at a farm located on the eastern shore of Port Susan Bay (Frenkel 1987). Cordgrass binds sediments around its dense root system thus stabilizing substrates and raising intertidal elevations. The initial introduction of English cordgrass had its intended effect, and the plant successfully grew and reproduced, creating large monocultures along the shoreline habitats of Port Susan Bay, Skagit Bay, Saratoga Passage, and Padilla Bay. Based on 1999 estimates, Spartina anglica has colonized ~3,300 hectares of Puget Sound intertidal habitat which solidly fills ~400 hectares (Hacker et al. 2001). Unfortunately, cordgrass invasions, and the ecosystem level modifications that they produce, have detrimental effects on native infaunal food webs, commercial shellfish, and migrating shorebirds (Goss-Custard and Moser 1988, Thompson 1991, Daehler and Strong 1996, O'Connell 2002). For this reason, active removal by the State of Washington, using mowing and herbicides, began in 1997 and has resulted in roughly a 20% decline (Hacker et al. 2001).
Spartina anglica has an interesting history that began in England in the late-1800s. Hybridization between two species, Spartina maritima (Curtis) Fernald (indigenous to Europe) and Spartina alterniflora Loisel. (indigenous to eastern North America), created the infertile hybrid Spartina townsendii H. & J. Groves (Marchant 1967, 1968) in the 1870's. A limited number of chromosomal doubling events of Spartina townsendii created the fertile allopolyploid later recognized as Spartina anglica (Raybould et al. 1991, Ferris et al. 1997, Ayres and Strong 2001). Ranwell (1967) has estimated that 175,000 plants or seeds collected from one site in England (Poole Harbour) have been distributed to 130 different sites worldwide since the mid-1920's. English cordgrass is invasive in a number of countries including Australia, China, New Zealand, and Tasmania.
We have been studying the pattern of Spartina anglica invasion by quantifying the extent of the spread in Puget Sound and measuring plant abundance and soil characteristics across an intertidal gradient at a number of infested sites. We have found that S. anglica invades four different habitat types that include low and high salinity marshes, mudflats, and cobble beaches (Hacker et al. 2001). It is most abundant (~200 solid hectares) in low salinity marshes where it forms monocultures in middle intertidal zones, displacing other native plant species. Spartina anglica is moderately abundant (~125 solid hectares) in mudflat habitats where it is most common in the high intertidal zone. It creates a raised marsh habitat by accumulating sediment around its extensive root system and facilitates the establishment of vascular plant species that are not normally present. Spartina anglica is much less abundant in high salinity marshes (~30 solid hectares) and cobble beaches (~5 solid hectares). In high salinity marshes, S. anglica is restricted to the lowest intertidal zones where it captures sediment and extends the low marsh edge out into mudflat habitat. At cobble beaches, it grows amongst cobbles and gravel in the high and middle intertidal zones, creating a root mat on top of the substrate that facilitates the growth of vascular plants and algae.
Little is known about the causes of cordgrass decline or the potential for restoration of previously invaded habitat. To explore this in more detail, we have combined information from management records with basic ecological information and newly collected data on cordgrass and native plant abundance. We determine that three main factors influence cordgrass control success and native habitat restoration (Hacker et al. in review). First, number of years and consistency of removal are critical. After four years, sites with consistent control showed 2.5 times greater decline than those with intermittent removal. Second, control success and restoration differed among habitat types with low salinity marshes having smaller cordgrass declines compared to mudflats and cobble beaches. High salinity marshes showed the best response. Moreover, the only sites that showed a fairly immediate restorative response to cordgrass removal were the low salinity marshes. Other habitats continued to retain legacy effects of the invasion. Third, spatial scale is important; larger invasions (>10 ha) had a lower percent decline than smaller (=10 ha) invasions suggesting that more extensive invasions exhibit proportionally lower cordgrass decline and potential for restoration.
Our work suggests that the nonindigenous cordgrass, Spartina anglica, is changing the nature of Puget Sound shorelines in which it invades. The potential for removal and restoration of native communities is uncertain and likely depends on the community considered. Future research will concentrate on post-removal community structure and restoration potential.
The research is supported through a grant to S. D. H. and M. N. D. from the National and Washington State Sea Grant Programs.
Abstract: Aim Presentation of an hypothesis suggesting that the extraordinarily similarity of the Russian Altai and the American Southern Rocky Mountain Flora represents an Oroboreal Flora; that had to have had an essential continuity across the northern part of the world in the Tertiary period, constituting a highland and steppe component of the betterknown Arcto-Tertiary Flora of eastern and far-western North America and eastern Asia. Location North America and Middle (Altai) Asia.
Methods: Summarization of the author's field and herbarium studies of whole floras over a period of over 60 years, consisting of successive specializations in vascular plants, lichens, and bryophytes.
Post Scriptum: This paper is available from the author as a PDF file; Dr. W.A. Weber's e-mail is: firstname.lastname@example.org