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