-------------- Original message from Elizabeth Leger <[EMAIL PROTECTED]>: -------------- [snip]
"If I measure 90-99% cover of exotic species in a system (totally the norm in California's central valley grasslands), I'm not supposed to be upset about the impacts of invasive species impacts because there haven't been any local extinctions? That makes no sense. Beth" I don't think anyone here has been saying that the impact of invasives is not important regardless of their role in extinctions. However, if you are measuring 90 to 99% cover of exotics in an ecosystem, at the very least some species must be threatened or endangered - both plant species who are crowded out by exotics and animal species which depend upon native species for food and shelter. The presence of invasives is becoming so universal that they are occupying growing percentages of available habitat. In addition to the folks at Smithsonian, the Fish and Wildlife Service, the National Park Service, the Forest Service, The Nature Conservancy, and many others must have data and publications about the impact of invasive exotics. Those groups have collaborated in the publication of popular materials on invasive exotics and acceptable substitute native species. As I recall these publications have extensive bibliographies. I will try to post references to them tomorrow or Thursday. Bob Mowbray -- Tropical Forest Ecologist Natural Resource Managment Specialist Reston, VA
