----- Original Message ----- From: Wayne Tyson To: [email protected] Sent: Wednesday, January 21, 2009 2:55 PM Subject: Ecosystem dynamics and function Colonizing Species Equilibrium and Disequilibrium Fw: [APWG] Fw: [INVASIVES] ISAC definition paper published
Ok, so I'm having trouble with the classification stream. But what do ecologists think about this paper and its conclusions and definitions? For example, as the paper summarizes: "Invasive species are those that are not native to the ecosystem under consideration and that cause or are likely to cause economic or environmental harm or harm to human, animal, or plant health. Plant and animal species under domestication or cultivation and under human control are not invasive species. Furthermore for policy purposes, to be considered invasive, the negative impacts caused by a non-native species will be deemed to outweigh the beneficial effects it provides. Finally, a non-native species might be considered invasive in one region but not in another. Whether or not a species is considered an invasive species depends largely on human values. By attempting to manage invasive species, we are affirming our economic and environmental values. Those non-native species judged to cause overall economic or environmental harm or harm to human health may be considered invasive, even if they yield some beneficial effects. Society struggles to determine the appropriate course of action in (Beck et al.: Invasive Species Definition N 419) [parentheses added] such cases, but in a democratic society that struggle is essential." Beck, K. George, Kenneth Zimmerman, Jeffrey D. Schardt, Jeffrey Stone, Ronald R. Lukens, Sarah Reichard, John Randall, Allegra A. Cangelosi, Diane Cooper, and John Peter Thompson. 2008. Invasive species defined in a policy context: Recommendations for the federal Invasive Species Advisory Committee. Invasive Plant Science and Management 1(4):414-421. A pdf file is available. WT
