I think Teresa is raising a very good point and to the best of my knowledge the answer to her question is no, there is little in the way of empirical evidence that invasive species cause extinctions or even local extirpations. The empirical evidence on loosestrife for example, is that although we see it everywhere it has not caused extinctions. Best.
jeff Houlahan -----Original Message----- From: Teresa Woods <[EMAIL PROTECTED]> To: [email protected] Date: Tue, 4 Apr 2006 13:49:11 -0500 Subject: invasive plants A couple articles to consider: Gurevitch, J. and D.K. Padilla. 2004. Are invasive species a major cause of extinctions? TREE 19:470-474. Davis, M. 2003. Biotic globalization: does competition from introduced species threaten biodiversity? BioScience 53:481-489. I couldn't believe the conclusions of these articles when I read them last year, but they did bring home the message that if indeed invasives are causing extinctions, even community level ones, we need to be documenting them in ways other than anecdotally. Hence, my question about relevant publications. I'd love to see them. As I said, even ones that show a correlation, as causation is justifiably hard to show. I am not as familiar with aquatic invasives except to know that some like zebra mussels are extremely aggressive and destructive. But regarding plants, invasives are often linked with disturbed habitats, and it may be that habitat destruction is the primary cause of local extinctions, and the invasives follow as the "final nail in the coffin (Gurevitch and Padilla 2002)." It is also likely that the extinction trajectories are definitely occuring but are longer-term, and just haven't reached the end yet. The link to the NYTimes article was, as I said, meant to fan the flames here -- not that I agree in any way with him, but to put on the table what landscape designers and architects are surely also being influenced by -- even if from, as has been correctly pointed out, a very biased point of view. So my query still stands -- is there empirical evidence supporting the sense that most of us have that invasives are causing native extinctions? I'd love to have evidence to contradict the NYTimes author's view. Teresa Teresa Woods Graduate Assistant Division of Biology 232 Ackert Hall Kansas State University Manhattan, KS 66506 785-532-9834 [EMAIL PROTECTED]
