JavaGAR
Explorer
Reged: 10/07/06
Posts: 357
Loc: New York State
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Many plants are used for landscaping in areas well beyond their natural range. One popular example is Honey Locust, which is indigenous to the Midwestern United States, but is grown extensively in cities and towns in the eastern part of the country. In some cases, including that of Honey Locust, the practice of growing plants outside their range is relatively harmless. However, some non-indigenous species, including the related Black Locust, are invasive and can crowd out indigenous plants in natural areas.
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diane9247
World Explorer
Reged: 01/15/07
Posts: 1414
Loc: Californian stranded in Oregon
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Hello JavaGAR -
The subject of your post - invasive plant species - is a pet peeve of mine. Here's the scourge of the California coast, Pampas grass (Cortaderia jubata):
 Nature.org
I hate the stuff! It quickly smothers all native plant species, leaving nothing but pampas and bare dirt. The coastal natives are tough, wind and drought resistant plants of large variety. But, two plants up to the challenge of annihilation are Pampas grass and Eucalyptus trees.  Both are escapees from backyards and have been spreading like crazy since the '50s.
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JavaGAR
Explorer
Reged: 10/07/06
Posts: 357
Loc: New York State
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Of course, one region's indigenous species is another region's exotic.
 We love Spartina on the East Coast.
 We hate Spartina on the West Coast.
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diane9247
World Explorer
Reged: 01/15/07
Posts: 1414
Loc: Californian stranded in Oregon
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 Yes, good point, Java - and good example! I remember reading about the Spartina plague in the SF Bay.
It strikes me that it's probably impossible to keep "their" flora and fauna from invading "ours" over the long run. I guess the difficulty is that it now happens so fast - for man-made reasons - that the natives don't have time to adapt to the invasion (e.g. evolve protective mechanisms). Is this anywhere near the right concept?
Diane
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Women for Women International - For the special needs of women surviving war.
Kiva - Small loans changing lives around the world.
Bukavu Foundation - For the Panzi Women's Shelter & other programs in Eastern Congo.
Room to Read - Change begins with educated children.
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JavaGAR
Explorer
Reged: 10/07/06
Posts: 357
Loc: New York State
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Diane:
>> "... don't have time to adapt..."
Yes, the pace of evolution compared to the pace of propagation of the plants leaves us with an invasion by the introduced species. Spartina alterniflora and Spartina townsendii found friendly physical conditions when they were introduced to the West Coast. In time, organisms that consume other plant species may gradually evolve toward exploiting these grasses as a food source and reduce their abundance. While that is happening, other species of plants that live in tidal marshes may gradually become more adept at competing with these grasses for space. But there is no guarantee that this will happen, as evidenced by the natural tendency for Spartina alterniflora to dominate the portions of tidal marshes below the mean high tide line on the East Coast.
The Japanese Beetle is an example of an introduced species that overwhelmed roses, willows, and other species of plants when it was introduced to the United States, but has since become much less abundant due to natural enemies.
Another interesting case is the introduced Ginkgo. While not invasive, it is noteworthy for its few natural enemies, perhaps because it nearly became extinct, which could have wiped out the organisms that depended on it as food.
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diane9247
World Explorer
Reged: 01/15/07
Posts: 1414
Loc: Californian stranded in Oregon
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Thanks for more good information. I barely remember anything from my college botany course, so this is fun to read about. Speaking of ginkgo biloba... here's a recent post.
I love this tree! I do remember reading that it's now rarely found in the wild, most being landscaping trees, now. I suppose that means it does not reseed easily.
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Women for Women International - For the special needs of women surviving war.
Kiva - Small loans changing lives around the world.
Bukavu Foundation - For the Panzi Women's Shelter & other programs in Eastern Congo.
Room to Read - Change begins with educated children.
Edited by diane9247 (03/06/08 07:19 PM)
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JavaGAR
Explorer
Reged: 10/07/06
Posts: 357
Loc: New York State
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Diane:
Thanks for the reference to the Ginkgo biloba post. It is easy to plant and grow Ginkgo seeds, and I have seen a few small trees in the Brooklyn Botanic Garden , growing in places where seeds evidently landed when they fell from nearby female trees. But this sort of occurrence is unusual. As the Ginkgo escaped its former natural enemies when it became rare, it probably also lost animals that were attracted to the smelly covering of its seeds. These animals may have eaten the seeds and spread them in their droppings. If these animals still existed, perhaps we would see more Ginkgo trees in the wild.
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