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The Global Invasive Species Team | |
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Global Invasive Species Team listserve digest #074 Tue Dec 26 2000 - 16:48:36 PST --CONTENTS-- 1. Weed job opening (Colorado) 2. Seeking case studies (Maryland) 3. Midwest invasive plant conference (Wisconsin) 4. Japanese hops (New York) 5. Recent weed articles (Nationwide) --------------------------------------- 1. Weed job opening (Colorado) From: Eric Lane (Eric.Lane(at)ag.state.co.us) -Eric Lane contacted the Wildland Invasive Species Team with news of a job opening. Application deadline is January 5. It is a two-year position funded by the Colorado Noxious Weed Management Fund. This winter, Colorado State University and the Colorado Department of Agriculture will hire a state noxious weed mapping specialist to develop maps of the distribution of targeted noxious weed species throughout Colorado....Good ArcView or ArcInfo skills are essential but so are good communication skills. For more information, contact Eric Lane. --------------------------------------- 2. Seeking case studies (Maryland) From: Donnelle Keech (dkeech(at)tnc.org) I am seeking case studies of invasive species control projects with well-done monitoring components, for a session at the Mid-Atlantic Exotic Pest Plant Council's August 2001 conference, *Invasive Plants: Taking Action of All Fronts*. I am interested in any suggestions, but will be especially excited about examples that are from the east, and were accomplished with modest resources. If you or someone you know has an illustrative monitoring and control project, please contact me. --------------------------------------- 3. Midwest invasive plant conference (Wisconsin) From: Mariquita Sheehan (msheehan01(at)fs.fed.us) The first day of this two-day conference (1-2 March, Eau Claire WI, $20 students/$40 non-student) is devoted to starting a state-wide weed council for Wisconsin, a badly needed organization that will help Wisconsin weed warriors pool their (meager) resources, team up with partners, and be more efficient in getting the bad word out. So if you can only come for one day I would encourage you to participate then. That said, both days are worth it. Other organizations will be meeting too, including Prairie Enthusiasts, WI Chapter of TWS, TNC. To learn more, go to: http://www.plantsoutofplace.org/ --------------------------------------- 4. Japanese hops (New York) From: Cris Winters (cwinters(at)tnc.org) Cris forwarded this question from a friend.... Have you had any experience with Japanese Hops (Humulus japonicus)? I have a couple of riparian projects which will be starting this coming spring, but there is hops everywhere. It appears the hops has killed many of the young saplings in the original buffer area on the James River. I am looking into the possibility of using some sort of herbicide to help control in addition to physical removal. However, I would like talk to someone who has actually done something with hops in past. --------------------------------------- 5. Recent weed articles (Nationwide) From: John Randall (jarandall(at)ucdavis.edu) 1)Invasive plants versus their new and old neighbors: a mechanism for exotic invasion. R.M. Callaway and E.T. Aschehoug. Science 290: 521-523 (Oct 20 2000). It is often argued that invasive non-native species succeed because they have escaped their natural enemies, however, the authors found that some may also gain advantage by competitive interactions that native species are not adapted to. In other words, the newcomers fight different than the locals! TNC's own Eric Ashehoug (now on the Santa Cruz Island project but at the time of this work a student at U Montana) and Ray Callaway of U Montana found Centaurea diffusa had much stronger negative impacts on native grass species it grows with in North America than on closely related grass species from its original habitat in the Old World. The differences appear to be due to differences in effects of C. diffusa's root exudates on other species and how this effects competition for other resources. 2)Biological control herbivores may increase competitive ability of the noxious weed Centaurea maculosa. Callaway, R.M., T. DeLuca and W.M. Belliveau. 1999. Ecology 80(4): 1196-1201. Ray Callaway and colleagues found that when biocontrol insects (knapweed root moth; Agapeta zoegana) fed on the roots of spotted knapweed (Centaurea maculosa), neighboring Idaho fescue (Festuca idahoensis) plants actually did more poorly than when grown with unattacked C. maculosa. Instead of releasing the neighboring grass from competition and allowing to thrive as intended, the insect had no detectable impact on knapweed and apparently indirectly suppressed the fescue. Knapweeds fed on by another non-native root feeder (Trichoplusia ni) it had smaller root systems and exuded more total sugars than knapweeds protected from attack. The authors hypothesize that moderate herbivory stimulated compensatory growth AND production of defense chemicals that also had allelopathic effects or otherwise altered the competitive relationship between the invasive knapweed and the native bunchgrass. They also suggest that some other biocontrol agents could be having indirect negative effects on some native species that are not yet recognized. 3)Mycorrhizae indirectly enhance competitive effects of an invasive forb on a native bunchgrass. Marler, M.J., C.A. Zabinski and R.M. Callaway. 1999. Ecology 80(4): 1180-1186. The authors found arbuscular mycorrhizae had no direct effects on either the invasive non-native spotted knapweed (Centaurea maculosa) or the native bunchgrass Idaho fescue (Festuca idahoensis) but apparently increased the negative impacts of spotted knapweed on Idaho fescue when the two plant species were grown together. This work was conducted in pots but soil taken from the field was used to inoculate treated pots with mycorrhizae. Idaho fescue plants grown with spotted knapweed without mycorrhizae were 171% bigger than those grown with the knapweed and mycorrhizae. On the other hand, spotted knapweed plants grown in competition with Idaho fescue were 66% larger in the presence of arbuscular mycorrhizae. These results suggest arbuscular mycorrhizae strongly enhance the ability of spotted knapweed to invade North American grasslands. 4)A test of community reassembly using the exotic communities of New Zealand roadsides in comparison to British roadsides. J.B. Wilson et al. 2000. Journal of Ecology 88: 757-764. In order to test competing theories about how plant communities come together, the authors compared communities from roadsides in areas with similar climates in Britain and in New Zealand where many species were introduced from Britain. While there were some similarities, the authors concluded 'that British species...in New Zealand assemble in communities some of which are not known in Britain'. They note that this agrees with evidence from the pollen and fossil record that although some communities appear to be very old, their component species were usually present in quite different assemblages in previous interglacial periods and even several thousand years ago during the present interglacial. The results are closest to the predictions of the Pre-adaptation hypothesis of community assemblage since the British species apparently fit into niches they hadn't met before arriving in New Zealand but for which they happen to have the right characteristics. The results also provide partial support for Stochastic and Deterministic hypotheses of community assemblage but do not support the Alternative Stable States hypothesis. 5)Combining mowing and fall-applied herbicides to control Canada thistle (Cirsium arvense) K. G. Beck and J.R. Sebastian. 2000. Weed Technology 14:351-356. Mowing one, two or three times before autumn applications of the herbicides picloram (Tordon), chlorsulfuron (Telar), clopyralid+2,4-D (Curtail) or dicamba (Banvel) provided inconsistent results and the authors conclude that such a combination should not be commonly recommended. |
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