Number 5, December 2011 From the Newsletter Editors

Newsletter Editors elcome to the fifth issue of the Visionary White Paper,” is in press and Rocky Mountain Research Station’s due out soon. It provides an overview of Dean Pearson, Research Ecologist W (RMRS) Invasive Species Science Update. RMRS invasives science coverage and USDA Forest Service—RMRS The newsletter is produced by the RMRS gaps through 2011. We’ll distribute it to this Missoula, MT 59801 Invasive Species Working Group (ISWG), mailing list and post it on our website at Phone: 406-542-4159 which is a core group of scientists who http://www.rmrs.nau.edu/invasive_species/ Email: [email protected] volunteer to coordinate outreach of RMRS index.php. All of our products, including http://www.rmrs.nau.edu/invasive_species/ invasive species science to managers all newsletters and publication lists, can index.php and the public. After publishing the past be found at this website. We want your four newsletters, we’ve concluded that an feedback on ways to improve this service Yvette Ortega, Ecologist annual issue will best represent the pace and encourage anyone who wishes to be USDA Forest Service—RMRS of new science and keep users abreast of an active participant in developing these Missoula, MT 59801 the latest research. Subsequent issues will products to join the ISWG. If you have Phone: 406-542-4152 occur each fall. The ISWG also disperses comments or questions, please contact Email: [email protected] its recent research findings through the ISWG team leader, Dean Pearson, periodic white papers and our website. [email protected]. Invasive Species Working Group The latest white paper, “Rocky Mountain Team Leader Research Station Invasive Species USDA Forest Service—RMRS Dean Pearson, Research Ecologist

Production Publishing Services USDA Forest Service—RMRS

This Issue …

▶ Wildfire’s influence on exotic plants ▶ Exotic forbs transform Intermountain grasslands

▶ Podcast on spider research ▶ Spread of noxious weeds through forest roads vs. treatment areas

▶ Brook trout vs. native cutthroat trout

▶ Replacing downy brome with native shrubs ▶ Ask the Expert: Are Eurasian collared-doves a threat? ▶ Upcoming Events ▶ Recent Publications on invasives research

1 Research Notes Exotic Plant Response to Wildfire on fire severity, with exotics being least present elsewhere in the study site before stimulated by fire in lightly burned areas, the fire. However, some new species were By: Paula Fornwalt ([email protected]. and most stimulated in moderately and truly new invaders that were not found in us), Research Ecologist, Forest and severely burned areas. Furthermore, the prefire surveys. The most notable new Woodland Ecosystems Program, Fort in moderately and severely burned invader was cheatgrass (Bromus tecto- Collins, CO areas, exotic richness and cover gener- rum), which was not found in the plots Fire is a key ecological process in ally increased as time since fire passed. until 2007, the last year surveys were forests of the western United States, and However, exotic richness and cover conducted. Continued monitoring of ex- it plays critical roles in regulating and remained low as of 2007, and correla- otic species is planned for 2012, 10 years sustaining native understory plant com- tions between native and exotic richness post fire, and will provide valuable in- munities. But fire can also help establish and cover suggest that exotics have not sight into longer-term patterns of postfire and spread exotic plant species. Given yet interfered with native understory exotic invasion. For more information, that the occurrence of fire—both wild and development. see Fornwalt and others (2010), in the prescribed—has increased in recent de- The prefire dataset also provided Recent Publications section on page 8. cades and is likely to continue to increase unique evidence that in the future, we must develop a thorough prefire exotic com- understanding of the factors influencing munity composition postfire exotic plant response. at both local (i.e., In 2002, the Hayman Fire burned plot) and landscape across 55,800 ha of Pinus ponderosa— (i.e., study site) scales Pseudotsuga menziesii (ponderosa strongly influences the pine—Douglas-fir) forest in the Colorado postfire exotic com- Front Range. Also burned in the fire were munity that develops pre-existing plots that had been surveyed at a given location. for understory plant composition and The researchers found cover in 1997. Researchers from Fort that regardless of fire Collins, Colorado, seized this opportunity severity, the exotic to examine the influence of the Hayman species that were pres- Fire on exotic plants by remeasuring the ent in a plot before the plots annually from 2003 to 2007. Their fire were also largely results were recently published in the present in the plot after journal Biological Invasions. the fire. Furthermore, Verbascum thapsus (common mullein), foreground, was the The researchers found that total exotic most new exotic spe- cies in a plot were most commonly encountered nonnative plant species following richness and cover were highly dependent the Hayman Fire.

Podcast Features Spider Research

A podcast produced by the Encyclopedia of Life and Atlantic Public Media features work by Research Ecologist Dean Pearson (Missoula, MT) on the effects of invasive plants on native spiders and food-web interac- tions. Encyclopedia of Life catalogs information about all species on the planet in a way that is interesting and user friendly. This research was also featured on National Public Radio’s “Living on Earth” series. To hear the podcast, visit http://education.eol.org/podcast/ branch-tip-spiders. Native Dictyna spider webs on plants of the exotic invader, spotted knapweed, at Lee Metcalf National Wildlife Refuge in western Montana. 2 Research Notes cont.

Native grassland in winter, western Montana. Native forbs have Invaded grassland in winter, western Montana. The flowering long senesced, leaving only the simple structure of native stems of exotic species such as spotted knapweed persist well bunchgrasses. beyond the growing season, providing ideal structures for native web-building spiders.

The Transformation of These differences depict a distinct of the exotics allowed populations of Intermountain Grasslands by niche separation between the dominant native web-building spiders to increase natives and invading exotics, which has by 80-fold. Additionally, native spiders Exotic Forbs: More Than Meets important implications for understand- built larger webs on the exotic substrates the Eye ing both invasibility of the system and that allowed each spider to double its invader impacts. With regard to the prey captures. The combined effect of By: Dean Pearson ([email protected]. invasibility of these systems, the fact increased spider numbers and increased us), Research Ecologist, Yvette Ortega that the five species of invaders exam- lethality of each spider has allowed ([email protected]), Ecologist, and Sa- mantha Sears, Biological Technician, ined represent five distinct plant families spiders in invaded habitats to suppress Wildlife and Terrestrial Ecosystems yet exhibit similar plant traits suggests some prey populations to such an extent Program, Missoula, MT that the success of these species may that their prey’s prey are released from hinge on their similar ability to exploit predation. These results show how even Intermountain grasslands of the an “empty niche” within these commu- subtle changes caused by invasion can northern Rocky Mountains are being nities. If so, these plant traits might be have extensive impacts that transmit transformed. Exotic forbs like spotted used to predict future invasions. With through four trophic levels. For more knapweed, leafy spurge, and Dalmatian regard to invader impacts, the distinctive information on this research, see Pearson toadflax have been invading for years shift in the structure and function of the (2009, 2010) and Pearson and others (in and are changing the structure and community indicates an invasion trajec- press) listed in the Recent Publications function of these systems. Although tory that predicts changes in community section below. Also check out the fol- intermountain grasslands are naturally interactions and ecosystem services. lowing article about a recently released rich in native forbs, the newcomers For example, later flowering times may podcast featuring this research. differ from native forbs in subtle but affect pollinators, later growing periods important ways. A recent study in may influence how fire interacts with western Montana by Dean, Yvette, and the vegetation, and shifts in the types of Samantha showed that dominant exotic biomass produced and decomposition forb species tend to put more energy into rates may affect nutrient cycling. flowering structures and to flower later The above postulated effects are than dominant natives, while natives reasonable but speculated based on tend to put relatively more energy into research in other systems. However, the vegetative growth and to synchronize researchers did quantify the extensive vegetative growth and flowering earlier outcomes of one subtle shift within in the season. The researchers found these communities—those resulting that senescence of flowering stems from changes in plant architecture. They also differed dramatically, with exotics found that the larger, more expansive, producing far more persistent flowering and more persistent flowering stems structures. 3 Research Notes cont.

Roads Trump Restoration Treatments in Their Effects on Noxious Weeds

By: Justin Runyon ([email protected]. us), Research Entomologist, Grass- land, Shrubland, and Desert Ecosys- tems Program, Bozeman, MT Burning and thinning treatments are being increasingly used in Western forests to manage insects, manage disease, and reduce wildfire hazards. Unfortunately, these tools can trigger the invasion and spread of invasive plants—something that could thwart successful restoration efforts. Land managers need to be aware Forest thinning treatments in the Tenderfoot Experimental Forest in Montana (left; photo by of this potential unwanted side-effect and Kevin O’Neill) had little impact on noxious weeds. Instead, forest roads (right; photo by Justin need to be armed with the knowledge to Runyon) were the key factor influencing the distribution of noxious weeds in this forest. best monitor and treat weeds following restoration. However, the effects of these in some treated areas, noxious weeds Many questions remain and more activities on the introduction and spread were confined to roadsides and did not research is needed on this topic. For of invasive plants are not well under- colonize treatments. This highlights the example, the Montana forest studied here stood. A recently published, long-term importance of roads for weed distribution is relatively weed-free and it is unclear RMRS study at Tenderfoot Experimental and spread, and it suggests that roadways if these findings can be extended to Forest in Montana helps shed some light should be considered when evaluating more heavily invaded forests or forests on the issue. the potential for invasion of exotic plants containing other weed species. It is clear In the study, the occurrence of noxious following restoration treatments. In that monitoring invasive plants, within weeds was monitored in treatment areas this forest, weed control along adjacent treated areas and along roads, should be (thinned and/or burned), untreated control roads and in heavily disturbed areas such a component of forest restoration. For areas, and along adjacent forest roads as slash piles may be a cost-effective more information, see Birdsall and others from 2001-2009. Interestingly, except for and efficient tactic to limit exotic plant (2011), listed in the Recent Publications Canada thistle, which invaded slash piles invasion. section on page 8.

Exotic Brook Trout Displace Cutthroat Trout in the West

By: Kevin S. McKelvey (kmckelvey@ fs.fed.us), Research Ecologist, Wildlife and Terrestrial Ecosystems Program, and Michael K. Young (mkyoung@ fs.fed.us), Research Fisheries Biolo- gist, Air, Water, and Aquatic Environ- ments Program, Missoula, MT Freshwater aquatic fauna are among our most endangered nationwide. Although the reasons for endangerment are many, few systems are as heavily impacted by nonnative invasive species. Native westslope cutthroat trout (top) and a nonnative brook trout (bottom), captured Indeed, many iconic invaders are aquatic: from Bostwick Creek, a tributary to the Gallatin River near Bozeman, MT. Brook trout are zebra and quagga mussels, Asian carp, implicated in the loss of cutthroat trout populations throughout the Rocky Mountains. and Eurasian water milfoil, to name a few. Many of these species have been or releases by the pet trade or pet own- notable exceptions such as the disastrous introduced in ways similar to the pri- ers. However, to a much greater extent, introduction of opossum shrimp Mysis di- mary pathways for terrestrial organisms, freshwater ecosystems have been subject luviana in lakes of the northern Rockies, either as stowaways as part of interna- to intentional and repeated introductions these intentional introductions involve tional commerce, escapees from farms, of exotic species. For the most part, with species of fish. 4 Research Notes cont. Salmo trutta (which originates from upstreammost extent of the distribution of Europe), and in small streams by brook fish, locations that are generally regarded trout. In western Montana and Idaho, to have pristine habitats that lack exotic In small, coldwater streams in the however, westslope cutthroat trout are species. inland West, the primary invasive fish much more widespread; they appear to Preliminary results suggest a disturb- species is the brook trout Salvelinus occupy over 50% of their historical range. ing pattern. Westslope cutthroat trout fontinalis, which is native to eastern Although brook trout are present in some seem much less widely distributed than North America. Brook trout were widely waters, they are thought to be much more was assumed during a recent (2005) stocked in streams in this region begin- limited in their distribution. “Thought” is assessment of their range. Moreover, ning in the late 1800s. Historically, these intentional here: little sampling of head- brook trout are present in about half of streams contained various subspecies water streams has been done. the small streams in western Montana and of cutthroat trout Oncorhynchus clarkii, In 2008, researchers from Missoula, northern Idaho, and in about a quarter of but cutthroat trout are now absent from Montana, began an extensive survey of all headwaters sites. In streams contain- much of this area. For example, in central western Montana and northern Idaho ing both species, brook trout usually (and Montana, where westslope cutthroat trout streams to document the distribution often dramatically) outnumber westslope O. c. lewisi were first identified by Lewis of all species of fish and amphibians cutthroat trout. In a substantial number and Clark, this subspecies occupies per- on Forest Service lands. We sampled of streams, as in central Montana, brook haps 5% of its historical range, primarily using intensive, single-pass electrofish- trout have completely replaced westslope in small streams above fish barriers. It has ing in over 1,000 reaches of nearly 400 cutthroat trout. This study will yield been replaced in large rivers by rainbow streams. Many of these reaches were many insights into the impacts of exotic trout O. mykiss (which was stocked from in the extreme headwaters of over 200 brook trout on native fish of the region. Pacific coastal waters) and brown trout streams. These sites were located near the

Treating Downy Brome with an article in Invasive Plant Science and year post-treatment. Imazapic was lethal Herbicide and Seeding With Management that investigated if treat- to downy brome at all growth stages in ments of imazapic and/or seeding with the greenhouse and reduced shrub ger- Native Shrubs native shrubs were effective in reha- mination by 50 to 80%, but older shrub bilitating shrublands highly invaded by seedlings were more tolerant of the her- By: Suzanne Owen ([email protected]. us), Chemist, and Carolyn Sieg downy brome on the Kaibab National bicide. These results highlight the need ([email protected]), Research Plant Forest in northern Arizona. Researchers to treat downy brome infestations before Ecologist, Forest and Woodland Eco- also determined the effects of imazapic they become too large. Removing thatch systems Program, Flagstaff, AZ on different growth stages of both downy before treating with imazapic, although brome and three native shrub species in likely lethal to the native shrubs in this Downy brome or cheatgrass (Bromus the greenhouse. study, could increase the effectiveness of tectorum L.) is one of the most invasive A one-time application of imazapic imazapic. Because imazapic can alter na- and widespread exotic plants in North combined with seeding shrubs was only tive plant communities, managers should America. Downy brome can reduce soil slightly effective in rehabilitating areas consider the unintended consequences of nutrient availability, alter native plant with high downy brome and thatch cover, this herbicide and the consideration of community composition, and increase fire and resulted in short-term impacts to other strategies for downy brome control, frequencies. The effectiveness of Plateau® nontarget species. In the field, seeding such as seeding native plant barriers and imazapic herbicide in reducing downy shrubs did not significantly increase shrub using herbicides that selectively reduce brome cover has been variable, and there density, although imazapic herbicide downy brome seed viability. For more is uncertainty about the impacts of ima- reduced downy brome cover and non- information, see Owen and others (2011), zapic on native species. Researchers from target forb cover by 20-25% and altered listed in the Recent Publications section Flagstaff, Arizona, recently published plant community composition the first on page 8.

Greenhouse experiment showing downy brome that was treated with the herbicide, imazapic (left), and water as a control (right).

Imazapic herbicide application to downy brome-invaded shrubland. The herbicide was mixed with an inert blue dye for visibility. 5 Research Notes cont. RMRS Biocontrol Team Releases Other News Accomplishments Report Preventing Forest Pest New Invasive Species Resource By: Deborah Finch ([email protected]), Grassland, Shrubland, and Desert Eco- Infestations systems Program Manager, Albuquer- The science organization, CABI, que, NM The Don’t Move Firewood campaign recently released a beta version of The Invasive Species Compendium, an online, The Station’s biocontrol researchers is a multimedia outreach effort seeking to educate the public about the threat of open access resource featuring detailed have prepared a five-year accomplishments information on the world’s invasive plants report (FY07-11) to showcase their work moving forest pests on firewood. Invasive forest pests such as the Asian longhorned and animals—their taxonomy, biology, titled “RMRS Weed Biocontrol Research: distribution, impacts, and management. Past Accomplishments, Current Status, beetle and emerald ash borer are well documented to disperse and cause new The website currently covers over 1,500 and Future Challenges.” Weed biocontrol species, and includes over 1,000 full text scientists conduct research to help stem infestations on contaminated firewood being moved by the public, and native articles and 70,000 abstracts linked to the invasion of exotic invasive plants in the species accounts. For more informa- the Interior West. The report highlights an insects such as the mountain pine beetle can also be spread to new uninfested tion, visit http://www.cabi.org/Default. emphasis on the publication of first-rate aspx?site=170&page=4127. science in respected peer-reviewed outlets areas by cut wood. By using a wide range (44 publications), and second, and perhaps of federal, state, and local partners, the more importantly, an emphasis on the time- Don’t Move Firewood campaign has ly provision of weed biocontrol application information and tools to managers on the ground (e.g., 25 additional publications in outlets aimed at managers). The research products and technology transfer activities are outlined in the report by the following scientists: George Markin (retired vol- unteer), Research Entomologists Justin TWS Joins the National Runyon and Sharlene Sing, Bozeman; Environmental Coalition on Supervisory Ecologist Jack Butler, Rapid Invasive Species City; Research Ecologist Dean Pearson The Goldenspotted oak borer caused and Ecologist Yvette Ortega, Missoula; significant mortality to oaks in California when it spread from its natural range (Mexico The Wildlife Society (TWS) became Research Ecologist Susan Meyer, Provo; and Arizona), possibly in contaminated an official member of the National and Research Plant Ecologist Rosemary firewood. Photo courtesy of Mike Lewis, Environmental Coalition on Invasive Pendleton, Albuquerque. See the full Center for Invasive Species Research, Species (NECIS) in September 2011. report at http://www.fs.fed.us/rmrs/docs/ Bugwood.org Established in 2003, the National home/weed-biocontrol-accomplishments. grown from a small program (initially Environmental Coalition on Invasive pdf. funded in 2008 by the USFS Northeastern Species (NECIS) is a national partnership Area, with help from a private founda- of several major environmental organiza- RMRS Weed Biocontrol Research: tions that provides a united expert and Past Accomplishments, Current Status, and Future Challenges tion) into a nationwide campaign that has scientific voice on invasive species poli- working relationships in more than half of RMRS Weed Biontrol Team the states. In 2012, Don’t Move Firewood cy. Its leaders include scientists, lawyers, Accomplishments Report activists, and advocates with many years Fiscal Years 2007-2011 anticipates being an integral part of the Interior West’s firewood outreach of experience on invasives policy. TWS, USDA Forest Service a professional scientific and educational Rocky Mountain Research Station program, as well as producing multiple products on request for the USFS Pacific association dedicated to excellence in Southwest Research Station and the wildlife stewardship through science and USFS Southeastern Area. The parent education, brings expertise on invasive organization of Don’t Move Firewood is plant and animal issues and looks forward The Nature Conservancy’s Forest Health to contributing to this coalition. Protection Program, a national initiative addressing threats to North American ecosystems. For more information on

Don’t Move Firewood, please visit http:// August 2011 www.DontMoveFirewood.org.

6 Ask the Expert

Q: Does the spread of Eurasian collared-doves pose a threat to native species?

Submitted by Nick DeCesare, PhD candidate, University of Montana, Missoula, MT

Answered by Yvette Ortega, RMRS Ecologist with a background in avian ecology and invasive species research ([email protected]); Wildlife and Terrestrial Ecosystems Program

A: The Eurasian collared-dove (Streptopelia decaocto) has invaded North America at a record pace. In 1982, this species arrived in Florida and has since rapidly spread to places as far as Montana and Alaska. The invasiveness of this species has raised concern over its potential impacts on native species, particularly related species such as the mourning dove. To date, little research has been done to address this question directly, but basic information on the life history and ecology of collared and native doves offers some insight. Both collared-doves and native doves feed primarily on seed and grain. However, the collared-dove is restricted to agricultural, suburban, and urban areas, where it takes advantage of artificial food sources such as bird feeders and cultivated fields. Because these food sources tend to be abundant in human-influenced habitats, the exotic dove is unlikely to compete significantly with native doves for food. However, in landscapes where trees used for nesting substrates are limited, collared-doves could reduce availability of nest sites for native doves. In addition, collared-doves could spread diseases to native birds given their ever-increasing abundance and their tendency to concentrate at feeding and roost sites. For example, collared-doves are a carrier for West Nile virus and may therefore contribute to the proliferation of this virus. Research is needed to examine the potential pathways of impact for this newly invasive bird.

Please submit your “Ask the Expert” questions to Dean Pearson ([email protected]).

Eurasian collared-dove, courtesy of Joy Voila, Northeastern University, Bugwood.org.

7 Upcoming Events:

Montana Weed Control Association 54th Idaho Weed Conference, Society for Conservation Biology North Conference, February 1-2, 2012, American Congress, January 11-13, 2012, Boise, ID July 15-18, 2012, Great Falls, MT (http://idahoweedcontrol.org/ Oakland, CA (http://www.mtweed.org/mwca- weedconference.html/) (http://www.scbnacongress.org/) conference-information/) 2012 Weed Science Society of America 96th Ecological Society of America Society for Range Management 65th Annual Meeting, Annual Meeting, Annual Conference, February 6-9, 2012, August 5-10, 2012, January 29-February 3, 2012, Big Island, HI Portland, OR Spokane, WA (http://www.wssa.net/) (http://www.esa.org/portland/) (http://www.rangelands.org/events/)

Recent Publications

Beckstead, J., S. E. Meyer, B. M. Connolly, Fornwalt, P. J., and C. C. Rhoades. 2011. Markin, G. P., and C. J. Horning. 2010. M. B. Huck, and L. E. Street. 2010. Rehabilitating slash pile burn scars in Discovery of a gall-forming midge, Cheatgrass facilitates spillover of a upper montane forests of the Colorado Asphondylia pilosa Kieffer (Diptera: seed bank pathogen onto native grass Front Range. Natural Areas Journal Cecidomyiidae), on Scotch broom species. Journal of Ecology 98:168-177. 31:177-182. (Cytisus scoparius (L.) Link) (Fabaceae). Journal of the Kansas Entomological Beckstead, J., L. K. Street, S. E. Meyer, Kim, M.-S., N. B. Klopfenstein, and Society 83:260-263. and P. S. Allen. 2011. Fire effects on G. I. McDonald. 2010. Effects of the cheatgrass seed bank pathogen forest management practices and Maron, J. L., D. E. Pearson, S. M. Hovick, Pyrenophora semeniperda. Rangeland environment on occurrence of and W. P. Carson. 2010. Funding Ecology and Management 64:148-157. Armillaria species. Journal Korean needed for assessments of weed Forestry Society 99:251-257. biological control. Frontiers in Ecology Birdsall, J., and G. Markin. 2010. and the Environment 8:122-123. Biological Control of Yellow Starthistle Kim, M.-S., and N. B. Klopfenstein. (Centaurea solstitialis) in the Salmon 2011. Molecular identification of Mazzola, M. B., J. C. Chambers, R. R. River Canyon of Idaho. Invasive Plant Armillaria gallica from the Niobrara Blank, D. A. Pyke, E. W. Schupp, K. Science and Management 3:462-469. Valley Preserve in Nebraska. Journal of G. Allcock, P. S. Doescher, and R. Phytopathology 159: 69-71. S. Nowak. 2010. Effects of resource Birdsall, J. B., W. McCaughey, and J. availability and propagule supply on B. Runyon. 2011. Roads impact the Kim, M.-S., J. W. Hanna, and N. B. native species recruitment in sagebrush distribution of noxious weeds more Klopfenstein. 2010. First report of ecosystems invaded by Bromus than restoration treatments in a an Armillaria root disease pathogen, tectorum. Biological Invasions 13:513- lodgepole pine forest in Montana, Armillaria gallica, associated with 526. USA. Restoration Ecology, doi: several new hosts in Hawaii. Plant 10.1111/j.1526-100X.2011.00781.x. Disease 94:1503. McGlone, C. M., C. H. Sieg, and T.E. Kolb. 2011. Invasion resistance Coop, J. D., R. T. Massatti, and A. W. Kim, M.-S., B. A. Richardson, G. I. and persistence: established plants Schoettle. 2010. Subalpine vegetation McDonald, N. B. Klopfenstein. 2011. win, even with disturbance and pattern three decades after stand- Genetic diversity and structure of high propagule pressure. Biological replacing fire: Effects of landscape western white pine (Pinus monticola) Invasions 13:291–304. context and topography on plant in North America: Implications for community composition, tree conservation and restoration. Tree Meyer, S. E., D. L. Nelson, and S. Clement. regeneration, and diversity. Journal of Genetics and Genomics 7:11-21. 2010. The ecological genetics of the Vegetation Science 21:472-487. Ustilago bullata-Bromus tectorum Lee, J. C., S. M. Hamud, J.F. Negrón, pathosystem: A role for frequency Fornwalt, P. J., M. R. Kaufmann, and T. J. J. Witcosky, and S. J. Seybold. dependent selection? American Journal J. Stohlgren. 2010. Impacts of mixed 2010. Semiochemical-mediated of Botany 97:1304-1312. severity wildfire on exotic plants in flight strategies of two invasive elm the Colorado Front Range. Biological bark beetles: A potential factor Meyer, S. E., T. E. Stewart, and S. Clement. Invasions 12:2683-2695. in competitive displacement. 2010. The quick and the deadly: Environmental Entomology 39:642-652. growth versus virulence in a seed bank pathogen. New Phytologist 187:207- 216. 8 Ortega, Y. K., and D.E. Pearson. 2011. Pearson, D. E., R. M. Callaway, and J. L. Schat, M., S. E. Sing, R. K. D. Peterson, Long-term effects of weed control with Maron. 2011. Biotic resistance via F. D. Menalled, and D. K. Weaver. picloram along a gradient of spotted granivory: Establishment by invasive, 2011. Growth inhibition of Dalmatian knapweed invasion. Rangeland Ecology naturalized and native asters reflects toadflax Linaria dalmatica (L.) Miller, in and Management 64:67-77. generalist preference. Ecology 92:1748- response to herbivory by the biological 1757. control agent Meeinus janthinus Ota, Y., M.-S. Kim, H. Neda, N. B. Germar. Journal of Entomological Klopfenstein, and E. Hasegawa. Pearson, D. E., Y. K. Ortega, and S. Sears. Science 47:232-246. 2011. The phylogenetic position of In press. Darwin’s naturalization an Armillaria species from Amami- hypothesis up-close: intermountain Scott J. W., S. E. Meyer, K. R. Merrill, and Oshima, a subtropical island of Japan, grassland invaders differ V. J. Anderson. 2010. Local population based on elongation factor and ITS morphologically and phenologically differentiation in Bromus tectorum L. sequences. Mycoscience 52:53-58. from native community dominants. in relation to habitat specific selection Biological Invasions. regimes. Evolutionary Ecology 24:1061- Owen, S. M., C. H. Sieg, and C. Gehring. 1080. 2011. Rehabilitating downy brome Peppin, D., P. Z. Fulé, C. H. Sieg, J. Beyers, (Bromus tectorum)–invaded shrublands M. Hunter, and P. Robichaud. 2011. Sing, S. E., and R. K. D. Peterson. 2011. using Imazapic and seeding with native Recent trends in post-wildfire seeding Assessing environmental risks for shrubs. Invasive Plant Science and in Western U.S. forests: Costs and seed establishing invasive species Dalmatian Management 4:223-233. mixes. International Journal of Wildland (Linaria dalmatica) and yellow (L. Fire 20:702-708. vulgaris) toadflax in North America. Pearson, D. E. 2009. Invasive plant International Journal of Environmental architecture alters trophic interactions Progar, R. A., G. Markin, J. Milan, T. Research and Public Health 8:2823- by changing predator abundance and Barbouletos, and M. J. Rinella. 2010. 2853. behavior. Oecologia 159:549-558. Inundative release of Aphthona spp. flea beetles (Coleoptera: Stella, K. A., C. H. Sieg, and P. Z. Fulé. Pearson, D. E. 2010. Trait- and density- Chrysomelidae) as a biological 2010. Minimal effectiveness of native mediated indirect interactions initiated “herbicide” on leafy spurge in riparian and non-native seeding following three by an exotic plant autogenic ecosystem areas. Journal of Economic Entomology high-severity wildfires. International engineer. The American Naturalist 103:242-248. Journal of Wildland Fire 19:746-758. 176:394-403.

Publications available on the RMRS Invasive Species Website: http:// www.rmrs.nau.edu/invasive_species/ publications.php

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