Ryan/Ed- >From my perspective, the phrase "native invasive" is a contradiction in terms, >and should be discontinued immediately, lest it gain coinage by being >"Google-able"....;>} A species native to the area or region (limits defined by vector capability, watershed, etc.) taking hold in a recent disturbance would come under the broad category of a pioneering species (a phrase used by many to describe species like aspen (in the west...;>)) which often takes hold in recent disturbances (like burns, blowdowns, etc.), lives a relatively short life while other more shade tolerant species get established and eventually dominate (or at least come to maturity). While my understanding of the eastern disturbance ecology is limited, my thinking is that laurel and rhododendron are native species that 'pioneer' well, after some kind of disturbance. My recall of rhododendron patches is that the tend to occupy the lower reaches, which I suspect might be the result of moving water events? Burns? In any case, they seem to take hold and sustain themselves for some time. I was asked once 'what is a weed'? My off the cuff, non-academic reply was any plant that I didn't want there...I love looking down on a mosaic of vegetation that includes rhododendron while in flower, but it would quickly attain "weed" status, at exactly the point I had to traverse it. -DonRB
Date: Thu, 11 Dec 2008 14:03:46 -0500From: [email protected]: [email protected]: [ENTS] Re: Shrub-layer an empty niche? Ed, I don't have a well developed idea about "native invasives." I am actually skeptical of the concept. I don't think of Rhododendron and Mountain Laurel as invasive, they came to mind as I was thinking about native shrubs that have a major impact on biodiversity and ecosystem function...Rhododendron certainly does in some areas. Its an impactful shrub, which I think is interesting, but really wouldn't go much beyond that- "interesting" particularly when thinking about the idea of an "empty niche." There have been a numbers of papers on Rhododendron dynamics, disturbance, etc. I think several papers from Coweeta...I don't know that literature at all. I think your comments about the grasses are right on. Disturbance (in all its forms) interacts quite directly with invasion in many systems. Sometimes removing disturbance causes the invasion, sometimes introducing disturbance facilitates invasion. As the responses to my first email have nicely suggested, the invasion process is complexity piled on complexity piled on complexity. best, rwm On Thu, Dec 11, 2008 at 11:11 AM, Edward Frank <[email protected]> wrote: Ryan, Are you saying that Rhododendron and Mountain Laurel are a native invasive in some conditions as opposed to the "normal" forest components? If so in what circumstances is this the case? It always struck me as a core component of the forest rather than something that should not be there. The definitions you provided are useful in these types of discussions on the list to make sure everyone is starting from the same basic perspective. The idea of native placeholders to help prevent the establishment of non-native invasives is interesting. I am wondering about what you think concerning the replacement of native grasses by invasive ones in some settings. this is a big problem in some patches of open prairie in the mid west. Another example is from some of the Allegheny River Islands, portions of the islands were open grassy areas. These have since been replaced by Japanese Stiltgrass. This may be do to the damming of the river upstream preventing the annual or at least frequent flooding of the islands. (The presumption being that the flooding was more favorable to the native species than it is to the invasives.) The same can be said for the invasive multiflora roses, the Knotweed, etc. The only areas in portions of the island not covered by the invasives, and still retaining a semblance of native species are areas still being flooded. The point being that changes in the natural processes of flooding, fire, etc, may actually result in less "disturbance" of the area and promote the rise of invasives. Some types of disturbances are needed to maintain the natural succession cycles and interrupting them may result in the invasion of both exotics and atypical native species. Obviously the grassy areas do not have shrub layer, but the process could be analogous to those affecting forest settings. Ed Join the Primal Forests - Ancient Trees Community at: http://primalforests.ning.com/ ----- Original Message ----- From: Ryan McEwan To: [email protected] Sent: Thursday, December 11, 2008 10:28 AM Subject: [ENTS] Re: Shrub-layer an empty niche? I imagine that if you focus on life history traits, some native species are "invasive," but, most deciduous forest shrub-layer species don't fall into that category in my view- Smilax, Viburnum, Lindera, etc., just dont have the same impact on biodiversity and ecosystem function as invasives such as Lonicera or Ligustrum. What about Rhododendron, though? I think it is an interesting case...and maybe Kalmia in some settings, I am sure there are others I am not thinking of. The other really important thing to keep in mind is that native weeds should not be considered "invasive" if they are part of an ephemeral community. Think of poke (Phytolacca)...it has all the features of an "invasive" species, but it does NOT form a persistent community...it is ephemeral, holding the niche for a brief time. Ultimately, I think native weeds might be the key for management of invasives...you need something aggressive to hold those disturbed areas until you can get the forest floor in place and some shade from the canopy. Native "weeds" like Phytolacca, Rubus, Eupatorium rugosum, maybe even Acer negundo, and others, might be very helpful in that context. ryan On Wed, Dec 10, 2008 at 11:18 PM, Steve Galehouse <[email protected]> wrote: Russ, ENTS-Not to be a heretic, but I think we have to realize we humans are as much agents of dispersal of plant species as are birds, squirrels, wind patterns, etc. Were it not native in my area, I think any of the Smilax species would be considered invasive, as well as Viburnum acerifolium and Vaccinium stamineum. The "alien" barberries, buckthorns, burning bushes and the rest that have become naturalized are now effectively native species--just because we can document how they came here from distant origins, doesn't mean they don't belong here in the grand scheme. We don't know how "native" species expanded their ranges, but I'm sure many did so with the help of human influence(agriculture). I also think that observing and recording the shrub layer of the forest, without taking in to account the herbaceaous layer, is limiting the mix of the forest community.Steve On Wed, Dec 10, 2008 at 1:48 PM, <[email protected]> wrote: ENTS: There is no doubt that the spread of certain invasive species is accelerated by white tail deer. In the Appalachians Microstegium vimineum, Japanese stiltgrass is changing the condition of the "natural" hardwood forest faster than researchers can keep up with the evolving idea of what a "natural" forest or "natural" regeneration is likely to be defined as in the future. Invasive plants are showing up in tracts of woodland where nothing more than a stream passing through the property is a part of the disturbance regime. In so many forested situations I have encountered, the invasive species are not filling in a vacant niche...they are replacing a dynamic and diverse forest understory comprised of hundreds of native plant species per acre with a green desert that consists of a dozen or less of the most persistent native plants fighting for space against the overwhelming assault of non resident alien invaders that are capable of altering their adopted environment to suit their needs while producing prodigious amounts of seed that enjoy extremely high germination rates in the absence of fertility depleting microorganisms that keep resident plan populations in balance. Again, the changes being wrought on our forests by climate change and nonnative plants, insects and diseases is validating the ENTS historical mission of documenting what a "natural" forest is by today's definition. Russ One site keeps you connected to all your email: AOL Mail, Gmail, and Yahoo Mail. The NEW AOL.com. -- Ryan McEwanThe University of Daytonhttp://academic.udayton.edu/RyanMcEwan -- Ryan McEwanThe University of Daytonhttp://academic.udayton.edu/RyanMcEwan_________________________________________________________________ Suspicious message? There’s an alert for that. http://windowslive.com/Explore/hotmail?ocid=TXT_TAGLM_WL_hotmail_acq_broad2_122008 --~--~---------~--~----~------------~-------~--~----~ Eastern Native Tree Society http://www.nativetreesociety.org You are subscribed to the Google Groups "ENTSTrees" group. To post to this group, send email to [email protected] To unsubscribe send email to [email protected] For more options, visit this group at http://groups.google.com/group/entstrees?hl=en -~----------~----~----~----~------~----~------~--~---
