next message in archive
next message in thread
previous message in archive
Index of Subjects
--Apple-Mail-3--285193088 Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset=US-ASCII; delsp=yes; format=flowed I am new to this thread, and have just read Lance's latest -- I would distinguish between aliens (non-natives) and invasives, and for all non-native additions to our fauna/ecosystems, I would consider the harm or disbenefits from the introduction and spread to be axiomatic or to be assumed until shown otherwise (very unlikely ever) -- in many or most or even all cases, all the various forms of harm from introduced organisms have not been studied and proven. Cheers from Jim in Wolfville. Begin forwarded message: > From: "Laviolette, Lance (EXP)" <lance.laviolette@lmco.com> > Date: March 21, 2012 1:43:00 PM ADT > To: "naturens@chebucto.ns.ca" <naturens@chebucto.ns.ca> > Subject: RE:[NatureNS] Invasives > Reply-To: naturens@chebucto.ns.ca > > Hi Paul, > > This is a very interesting question. I know David Webster has > commented on invasives before as has Fred Schueler so I look > forward to their input on the subject. Personally, I don't think > there is a definitive answer. > > For example, should we limit our view to Nova Scotia, expand it to > Canada or remove the political boundaries from the equation and > look at North America. What time frame should we look at when > evaluating a species? The last century, since Europeans arrived, > since the last ice age or longer? Many species would have crossed > into North America on the land bridge from Asia after the last ice > age and even today there are at least some bird species that are > 'colonizing' Canada from elsewhere. > > One provincial government that shall remain nameless but is > composed of Toronto Maple Leaf fans, defines invasive species as > "... coming from other countries or regions and moving outside > their native habitat". Depending on how restrictive a definition > is placed on "native habitat" this would seem to rule out a number > of species that are often considered invasive. House Sparrows for > instance. For the most part, they are certainly occupying the same > habitat (broad definition) as they are in Europe. Perhaps a human > assistance component must be added in for something to be > considered 'invasive' but this isn't in their definition. Perhaps > some things we consider invasive aren't really invasive in the > truest sense of the word. Or perhaps a measure of negative impact > to the existing, established species should be taken into account. > If that were the case, House Sparrows would fall under the invasive > category. > To get back to your original question Paul, I think the time frame > of consideration has been artificially restricted to within the > past 100 years or so and the area of consideration is again > artificially set by whichever group or agency is looking at it. > Anything which has arrived within this time frame and in the area > under consideration via some form of human assistance is popularly > considered invasive. Having defined these parameters, personally I > don't think there is a time limit after which the invasive becomes > native. Once an organism has been labeled as invasive it stays as > invasive. If it has escaped this scrutiny (e.g. earthworms through > most of North America are of European settler origin I believe) > they are thought of as at worst, non-native rather than invasive. > All the best, > Lance > > From: naturens-owner@chebucto.ns.ca [mailto:naturens- > owner@chebucto.ns.ca] On Behalf Of Paul MacDonald > Sent: Wednesday, March 21, 2012 10:29 AM > To: Nature NS > Subject: EXTERNAL: [NatureNS] Invasives > > Hi All > We see a lot about invasives nowaday, birds, fish and so on. > My question is how long does a species have to be in the province > before it changes from an invasive to become a native? > Seems to me the word has become similar to d*mn > or other words the Maple Leaf fans will be using today LOL > At some point the DNA of these new species can be differanted from > DNA of other populations. > Lake whitefish are a good example. Nobody can be sure if the ones > we have in our midst are native or if they are descendants of > stocked fish > about 100 years ago. > Have a nice day > Paul > > --Apple-Mail-3--285193088 Content-Transfer-Encoding: quoted-printable Content-Type: text/html; charset=US-ASCII <html><body style=3D"word-wrap: break-word; -webkit-nbsp-mode: space; = -webkit-line-break: after-white-space; "> I am new to this thread, and have just read Lance's latest -- I would = distinguish between aliens (non-natives) and invasives, and for all = non-native additions to our fauna/ecosystems, I would consider the harm = or disbenefits from the introduction and spread to be axiomatic or to be = assumed until shown otherwise (very unlikely ever) -- in many or most or = even all cases, all the various forms of harm from introduced organisms = have not been studied and proven.<div><br></div><div>Cheers from Jim in = Wolfville.</div><div><div><br><div>Begin forwarded message:</div><br = class=3D"Apple-interchange-newline"><blockquote type=3D"cite"><div = style=3D"margin-top: 0px; margin-right: 0px; margin-bottom: 0px; = margin-left: 0px; "><font face=3D"Helvetica" size=3D"3" color=3D"#000000" = style=3D"font: 12.0px Helvetica; color: #000000"><b>From: = </b></font><font face=3D"Helvetica" size=3D"3" style=3D"font: 12.0px = Helvetica">"Laviolette, Lance (EXP)" <<a = href=3D"mailto:lance.laviolette@lmco.com">lance.laviolette@lmco.com</a>>= ;</font></div><div style=3D"margin-top: 0px; margin-right: 0px; = margin-bottom: 0px; margin-left: 0px; "><font face=3D"Helvetica" = size=3D"3" color=3D"#000000" style=3D"font: 12.0px Helvetica; color: = #000000"><b>Date: </b></font><font face=3D"Helvetica" size=3D"3" = style=3D"font: 12.0px Helvetica">March 21, 2012 1:43:00 PM = ADT</font></div><div style=3D"margin-top: 0px; margin-right: 0px; = margin-bottom: 0px; margin-left: 0px; "><font face=3D"Helvetica" = size=3D"3" color=3D"#000000" style=3D"font: 12.0px Helvetica; color: = #000000"><b>To: </b></font><font face=3D"Helvetica" size=3D"3" = style=3D"font: 12.0px Helvetica">"<a = href=3D"mailto:naturens@chebucto.ns.ca">naturens@chebucto.ns.ca</a>" = <<a = href=3D"mailto:naturens@chebucto.ns.ca">naturens@chebucto.ns.ca</a>></f= ont></div><div style=3D"margin-top: 0px; margin-right: 0px; = margin-bottom: 0px; margin-left: 0px; "><font face=3D"Helvetica" = size=3D"3" color=3D"#000000" style=3D"font: 12.0px Helvetica; color: = #000000"><b>Subject: <