Interesting question and responses. Humans are part of nature, and some of humans’ actions/disturbances make it easier for invasive species to flourish. (Some would suggest that humans are the worst invasive species on the planet.) Some of humans’ actions cause large-scale changes to “natural” systems (sometimes for better, often for worse - but of course that is just an anthropocentric view), and then other humans’ actions are focused on reversing those changes (making what got worse, better). It makes me think about the larger issue of climate change. Many (myself included) believe that humans’ accelerated use and burning of fossil fuels during the past century has caused the climate changes that are occurring. Others believe that climate change is simply a natural occurrence, and humans’ actions did little to cause it and will do little to reverse it. Still others don’t believe climate change is happening at all. What’s happening is happening, whatever one may “believe”. If enough of us believe climate change is happening, is caused by man, and can be slowed or reversed, then actions will be taken to do so. If not, then whatever is happening will continue, possibly with catastrophic effects on the survivability of some, many, or all humans. The “natural” world will continue on regardless, with or without humans. Species will continue to fill in niches wherever they are best adapted. Steve In a message dated 4/22/2012 11:17:45 A.M. Eastern Daylight Time, the.ts...@gmail.com writes:
Hi Josh, Interesting post! The terms "adaptation, progression, and ecosystem evolution" are confusing to me. But, I think I understand your point, and in my classes the cleverest students typically will ask me the same kind of question you posed to Ecolog! I think one of the obvious reasons that invasive species are a concern is that they can have a strong negative impact on biodiversity. This has been shown in numerous systems, and publications. But, as an example, just yesterday I was on a hike with a group in a place near Dayton, Ohio called "The Glen." This is a limestone gorge covered with deciduous forest. In areas of this forest where the manager actively works, the herbaceous layer at this time of year is extremely species rich. We didnt lay down a plot, but in some areas we counted 20 (or so) native species of herbaceous plant within a very small area (1m2 or so). These small patches are where the manager can hold at bay an incredibly potent invasion of garlic mustard (among other species). In the invaded sites (which make up the vast majority of the forest floor), within roughly the same area (1m2 or so), the species diversity is extremely low and we basically didnt see any of the native species. It is very clear that garlic mustard, privet, Amur honeysuckle, and other species in this site are playing by different rules than the natives. They are going to win, and the native species will lose, unless there is intervention. So, I think It comes down to what is your tolerance for the loss of native biodiversity? It is probably the case that the system will eventually come to some kind of new equilibrium as pathogens/pests and some of the native species "figure out" how to deal with these new species, but we dont have a timeline for this. Could it be 100 years? An eye-blink on geologic time scales, no doubt, but plenty of time for site-specific biodiversity to be drastically reduced. Many of the native species in question at The Glen (e.g., Erythronium, Sanguinaria) are "slow plants" (sensu Glenn Matlack) and have very low reproductive and dispersal rates. So there is good reason to believe that this biodiversity loss could be permanent. Bottom line- are you okay with letting species richness drop from "incredibly rich" to "extremely low"? And, I am not asking you Josh, I think that is a question for natural areas management. If they say "NO!!" then it is part of our job as ecologists to figure out how to best achieve the goal. In the meantime, invasive species allow us to ask some really interesting questions about how ecological communities are assembled! Best, Ryan -- Ryan W. McEwan, PhD Assistant Professor Department of Biology The University of Dayton 300 College Park, Dayton, OH 45469-2320 Office phone: 1.937.229.2558 Lab phone: 1.937.229.2567 Office Location: SC 223D Email: ryan.mce...@udayton.edu Lab: http://academic.udayton.edu/ryanmcewan On Sun, Apr 22, 2012 at 10:01 AM, Joshua Wilson <joshua.m.wils...@gmail.com>wrote: > Good morning, > > I know that invasive and non-native species have been getting a great deal > of attention lately, and justly. I understand the basic ecological impacts > and concerns invasive species cause, and the disruption of the native > system. My main question is: > > Why are invasive species considered a nuisance, instead of adaptation, > progression, or perhaps ecosystem evolution? > > Yes, human beings have been a main cause of the large majority of these > invasions. But even so, I feel we are part of the natural system. If an > invasive species exhibits more plasticity or is more competitive and > adaptive than the present species in an ecosystem, does that necessarily > imply catastrophic impacts? There are multiple arguments against this, I > know, many of them strong and verified. I am not an advocate of invasive > species dominated ecosystems, but am just curious why this change and shift > is considered so extremely detrimental. I feel that stable and progressive > change and adaptation is the basis of a strong ecological system. > > I would welcome any thoughts on this, or perhaps to start a discussion. I > am still an undergrad, so my question may seem farfetched and ridiculous to > some. Even so, just something to ponder on a lovely Sunday morning. > > Have a good day all, > > Josh Wilson >
