A lot of good points and examples being brought up on both sides of the issue here.
Wayne's comment about healthy ecosystems needing far less intervention by us than we think is particularly interesting. From my experience, that is true, but the problem is in finding a healthy ecosystem. Pretty much wherever we go we, pave, plow, cut, dig, and trample. Those activities are not conducive to a healthy, robust ecosystem which can either fend off invasive or gracefully accept them. Those activities promote organisms which can cope with fragmented and disturbed habitats. Malcolm rightly reminds us that not all invasives are exotic, Even native organisms can occupy an invasive niche when the environment changes, often as a result of the previously mentioned activities. And a final note about tamarisk... it's called the "Willow leaf flycatcher" for a reason, it's not called the "Tamarisk flycatcher". True, the birds are now sometimes nesting in tamarisk, but that's only because in may places it is the only remaining dense stand of vegetation they can nest in. From my reading and conversations with friends who have worked in tamarisk blighted areas there is less food in tamarisk vegetation for the birds, and the decline of both cottonwoods and willows does appear to be pretty closely linked with the spread of tamarisk. I think the main point to keep in mind when thinking of managing invasives is more one of practicality and well though out approaches. Not to belabor the tamarisk example, but many of the management approaches are doomed to failure because the removal begins at the bottom of the watershed (easier access) rather than at the top of the watershed (the point of origin for propagules). In this and other conservation areas I think we need to sit down and have a really deep think about what our goals are, how we will achieve them, and why we set those specific goals. Neahga Leonard
