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The Global Invasive Species Team |  |
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Introduction First slide Slide #5 Slide #10 Slide #15 Slide #20 Slide #25 Slide #30 Slide #35 Slide #40 Slide #45 Slide #50 Slide #55 Slide #60 Slide #65 Slide #70 Last slide |
WEED
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Before continuing, here are some definitions of terms that
will be used in this presentation. "Weed"
designates an organism
(usually but not always a plant) that is not wanted in a given area, generally
because it causes damage or otherwise interferes with management goals.
In Australia non-native species that invade and degrade conservation areas are
called "environmental weeds", which clearly
distinguishes those species
regarded as pests in conservation areas (nature preserves, etc.) from
weeds of agricultural areas, lawns, gardens, etc. Most "environmental
weeds" are not native to the area where they are regarded as problems. In
this presentation "non-native" is used for species that were directly
or indirectly introduced to a given region by humans, which were not
present in the region before-hand and which would not have spread into the area
without human interference.
"Exotic", "alien", and
"non-indigenous" are all
synonyms of "non-native". "Invasive species" are those that spread into areas where they are not native. This definition includes all non-native species that escape or otherwise grow outside cultivation whether or not they have known harmful effects, and is in line with definitions of invasive species used by many other ecologists (e.g. di Castri, 1990; Kolar & Lodge, 2001; Lincoln et al., 1998; Rejmanek, 1995; Rejmanek et al., 2002; Richardson et al., 2000; Shigesada & Kawasaki, 1997; and Williamson, 1996). Note that this differs from definitions used by some other ecologists and conservation workers which include only species that cause significant negative ecological effects (e.g. Cronk & Fuller 1995, Davis & Thompson 2001). Also note that not all non-native plants are invasive and, in fact, only a small minority of the tens of thousands of species introduced to North America have escaped cultivation, and of that subset many are not invasive in wildlands. "Noxious" is a term for species or groups of species that have been legally designated as pests, for example by a county, state or federal (national) agency. Not all such designated "noxious" weeds are problems in conservation areas and only a small subset of the species which are problems in conservation areas have been designated as "noxious". |
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| Slide 07 |
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