TIPSII CONFERENCE 2014

TERRESTRIAL INVASIVE PLANT SPECIES II Plant Invaders: Friends, Enemies, and Interactions

August 6-8, 2014 University of Toronto

Mississauga, Ontario Canada

Scientific Committee Peter Kotanen, University of Toronto Mississauga Sandy Smith, University of Toronto Roberta Fulthorpe, University of Toronto Scarborough Ben Gilbert, University of Toronto Marc Cadotte, University of Toronto Scarborough Pedro Antunes, Algoma University Colin Cassin, University of Toronto Mississauga

Sponsor The Terrestrial Invasive Plant Species Conference II is being funded by the Invasive Species Centre, and hosted in partnership with the University of Toronto Mississauga

Table of contents

Conference at a Glance ............................................................................................ Page 1

Conference Schedule .......................................................................................... Page 2 - 6

Extracurricular Activities .......................................................................................... Page 7

Keynote Biographies ................................................................................................ Page 8

Abstracts ........................................................................................................... Page 9 - 38

Participants ..................................................................................................... Page 39 - 40

Map: University of Toronto Mississauga ............................................................... Page 41

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Conference at a Glance WEDNESDAY, AUGUST 6

08:00 – 17:00 Field Trip: Carden Plain

18:00 Pre-Conference Social The Crooked Cue, Port Credit

THURSDAY, AUGUST 7

08:00 – 9:00 Registration & Coffee

09:00 – 9:15 Opening Remarks

09:15 – 10:30 Keynote: Spencer Barrett

10:30 – 10:50 Coffee Break & Networking

10:50 – 11:50 Evolutionary History & Adaptations of Invasive Species Rachel Germain, Brechann McGory, Connor Fitzpatrick

11:50 – 12:00 2 Minute Introductions Gwyneth Govers, Scott MacIvor, Christina Thomsen

12:00 – 13:30 Lunch & Posters

13:30 – 14:30 Ecology & Impacts Krystal Nunes, Heather Hager, Stuart Livingstone

14:30 – 14:50 Coffee Break & Networking

14:50 – 16:50 Invasions Go Underground: The Ecology of Plants, Soils & Soil Organisms Nicola Day, Colin Cassin, Michael McTavish, Pedro Antunes, Luke Flory, Dilhari Fernando

16:50 – 19:00 Day 1 Closing Remarks

19:00 Grad Student Mixer The Free Time Café

FRIDAY, AUGUST 8

08:00 – 9:00 Registration & Coffee

08:30 – 10:00 Biocontrol Symposium Sandy Smith, John Gaskin, Bernd Blossey, Lindsay Milbrath, Rob Bourchier

10:00 – 10:20 Coffee Break & Networking

10:20 – 11:40 Biocontrol Symposium Richard Shaw, Richard Casagrande, Hariet Hinz, Rob Bourchier

11:40 – 12:00 Biocontrol Planel Q&A

12:00 – 12:10 2 Minute Introductions Dianne Watkins, Michael McTavish, Brechnan. McGory, Zachary Teitel

12:10 – 13:30 Lunch and Optional Credit Valley Walk

13:30 – 14:45 Keynote: Kirsten Prior

14:45 – 15:10 Coffee Break & Networking

15:10 – 16:30 Managing Invasions Jennifer Dacosta, Ed Hanna, Alison Kirkpatrick, Prabir K.Roy

16:30 Student Awards & Closing Comments Peter Kotanen

PRESENTING AUTHOR IN BOLD FONT

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Wednesday, August 6

8:00 Optional Field trip – Carden Plain (Return 5pm)

18:00 Pre-Conference Pub Night (The Crooked Cue, Port Credit)

Thursday, August 7

8:00 Registration and Coffee

9:00 Opening Remarks

9:15 Keynote Address: Invasion Genetics: The Baker and Stebbins Legacy

Spencer Barrett, University of Toronto

10:30 Coffee break & networking

Session 1: Evolutionary History & Adaptation of Invasive Species

10:50 The evolution of species invasion potential

R. Germain & B. Gilbert

11:10 Adaptive potential in invasive ragweed

B. McGory & J.R. Stinchcombe

11:30 The influence of plant phylogenetic and functional relatedness on plant-soil

feedbacks

C. Fitzpatrick, L Gehant, P Kotanen & M Johnson

11:50 Two-minute introductions:

Gwyneth Govers, University of Waterloo

Scott MacIvor, York University

Christina Thomsen, University of Ottawa

PRESENTING AUTHOR IN BOLD FONT

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Thursday, August 7

12:00 Lunch & Poster Session

Poster 1: Thirty to fifty years of change in upland forest understory

communities of southern Ontario, west of Lake Ontario

M. Apostoli, T. Carleton & P. Maycock

Poster 2: Bloodroot (Sanguinaria canadensis) as a deterrent to the spread of

invasive garlic mustard (Alliaria petiolata)

G. Govers, M. A. Smith & S. D. Murphy

Poster 3: Pollen allelopathy: Taraxacum officinale pollen depresses seed set of

montane wildflowers

D. Loughnan, J. D. Thomson, J. E. Ogilvie & B. Gilbert

Poster 4: Adaptation to biocontrol? Testing for phenotypic divergence among

populations of an invasive plant

R. Sargent & M. Stastn

Poster 5: Demographic consequences of soil moisture variation for an invasive,

hybridizing weed

Z. Teitel & L. G. Campbell

Session 2: The Ecology and Impacts of Invasive Plants

13:30 Spatial variation in aboveground herbivory of native and exotic Asteraceae

K. A. Nunes, C. M. Cassin & P. M. Kotanen

13:50 Effects of a potentially invasive Miscanthus grass on local vegetation

communities and soil seed bank

H. Hager, L.D. Quinn & J.A. Newman

14:10 Effects of the invasive vine Vincetoxicum rossicum on ecosystem multi-

functionality

S. Livingstone

14:30 Coffee Break & Networking

PRESENTING AUTHOR IN BOLD FONT

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Thursday, August 7

Session 3: Invasions Go Underground: The Ecology of Plants, Soils & Soil Organisms

14:50 Plant-soil feedbacks along an invasion chronosequence

N. Day, P. M. Antunes & K. E. Dunfield

15:10 The role of invasive earthworms in forest community seed predation

C. Cassin & P. M. Kotanen

15:30 Resistance or susceptibility? Invader interactions between garlic mustard

(Alliaria petiolata) and the common nightcrawler earthworm (Lumbricus

terrestris) in Ontario forests

M. McTavish S. D. Murphy & S. Smith

15:50 Multi-trophic interactions determine competition and abundance among exotic

and native plants in communities

P. Antunes, V. Reininger, L. Martinez-Garcia, L. Sanderson & A. Dukes

16:10 Origins and impacts of emerging pathogens in invaded plant communities

L. Flory, K. B. Stricker, P. F. Harmon, K. Clay & E. M Goss

16:30 Challenges and opportunities in managing invasive species

D. Fernando

16:50 Close of first evening. Organization of dinner parties in Toronto.

19:00 Grad student mixer and networking event (The Free Times Café)

PRESENTING AUTHOR IN BOLD FONT

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Friday, August 8

8:00 Registration and Coffee

Session 4: Biocontrol Symposium

8:30 Introduction: The promises and challenges for biocontrol

S. Smith

8:40 Extreme differences in population structure and genetic diversity for three

invasive congeners: knotweeds in western North America

J. Gaskin, M. Schwarzländer, F. S. Grevstad, M. A. Haverhals, R. S. Bourchier

& T. W. Miller

9:00 A tale of two invaders: lessons from ecological assessments of native and

introduced Phragmites and garlic mustard

B. Blossey, V. Nuzzo, A. Dávalos, L. M. & J. Cohen

9:20 Demographic matrix models of swallow-wort (dog-strangling vine, Vincetoxicum

species) and projected agent impacts

L. Milbrath, A.S. Davis & J. Biazzo

9:40 Misconceptions about classical biological control of weeds

R. Bourchier, U. Schaffner & H.L. Hinz

10:00 Coffee & Networking Break

10:20 Japanese knotweed biocontrol – A shaky start

R. Shaw, R. Eschen & A. Brook

10:40 Potential biocontrol introductions against exotic Phragmites australis in North

America

R. Casagrande, B. Blossey, L. Tewksbury & P. Häfliger

11:00 Will any of the potential biological control agents against garlic mustard ever

get a green card?

H. Hinz, E. Gerber, J. Katovich & R. Becker

PRESENTING AUTHOR IN BOLD FONT

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Friday, August 8

11:20 Release of Hypena opulenta for biological control of dog-strangling vine

(Vincetoxicum) in North America

Rob Bourchier, Aaron Weed, Lisa Tewksbury, Naomi Cappuccino, Sandy Smith,

A. Gassmann & R. Casagrande

11:40 Biocontrol panel question & answer

12:00 Two-minute introductions:

Dianne Watkins, University of Waterloo

Michael McTavish, University of Waterloo

Brechnan McGoey, University of Toronto

Zachary Teitel, Ryerson University

12:10 Lunch & Optional Credit Valley Walk

13:30 Keynote Address: Enemy release and invasional meltdown: the role of friends

and foes in facilitating the success and impacts of invasive species

Kirsten Prior, University of Florida

14:45 Coffee & Networking

Session 5: Managing Invasions: Prediction, Monitoring & Control

15:10 Main drivers of invasibility of managed boreal and northern temperate forests

F. W. Bell, J. Dacosta, P. M. Antunes, I. Aubin, S. Hunt, M. Sharma

& S. G. Newmaster

15:30 A stochastic bioeconomic invasive species management system

E. Hanna

15:50 Early detection and distribution mapping system Ontario

A. Kirkpatrick

16:10 Invasive phragmites (Phragmites australis) monitoring and management.

P. K. Roy

16: 30 Student Awards and Closing Comments

Peter Kotanen, Conference Organizer, University of Toronto Mississauga

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Extracurricular Activities Wednesday August 6 2014 – Carden Plain Field Trip Location: Carden Plain Time: 8:00am – 5:00pm Shuttles will depart Wednesday morning for the Carden Plain alvar (http://www.couchichingconserv.ca/in-the-field/the-carden-plain/). A series of tours led by the Couchiching conservancy will cover the natural history of the local flora and fauna. Participants will also get the opportunity to see the most current progress in a dog-strangling vine (Vincetoxicum rossicum) biological control release program. For more information please see the TIPS2 website (https://secure.utm.utoronto.ca/tips2/). Wednesday August 6 2014 – Preconference Social in Port Credit Location: The Crooked Cue, Lakeshore Rd. E., Port Credit Time: 6:00pm A preconference social will take place at the Crooked Cue (~8km South of UTM) beginning at 6:30pm (http://www.crookedcue.ca/mississauga). The Cue offers a friendly atmosphere, 20+ beers on tap, and ample pool tables. Shuttle service for TIPS2 registrants will be provided from the restaurant to the UTM campus. If you are staying downtown please feel free to give the UTM-St. George shuttle a try (http://www.utm.utoronto.ca/shuttle/). Thursday August 7 2014 – Grad Student Social & Networking Event Location: The Free Times Café, Spadina Ave. & College St., Toronto Time: 7:00pm All TIPS2 attendees and guests are invited to a special networking event at The Free Times Café in downtown Toronto (http://www.freetimescafe.com/). Please join us for a couple of drinks and hors d'oeuvres at this great centrally located venue. Shuttle service will be provided from UTM once the day's final talk is over; return by the UTM-St. George shuttle (http://www.utm.utoronto.ca/shuttle/).

8

Keynote Biographies

SPENCER BARRETT is a leading authority in plant evolutionary biology, specializing in the ecology and evolution of plant reproduction. Dr. Barrett’s work is of general significance for two reasons. First, he has provided some of the most compelling experimental evidence of the selective mechanisms responsible for evolutionary transitions in plant sexual systems. Second, he has pioneered a functional view of angiosperm reproduction in which interactions among flowers, inflorescences and plant architecture take center stage, and mating and its consequences are interpreted within the broader context of life-history evolution. These contributions have helped to rejuvenate plant reproductive biology and make it one of the most active areas within ecology and evolutionary biology. For his original contributions to this field he received the prestigious E.W.R. Steacie Award in 1988 and was elected to Fellowship of the Royal Society of Canada in 1998 and Royal Society of London in 2004. He currently holds the Canada Research Chair in Evolutionary Genetics at the University of Toronto More information on Dr. Barrett's research may be found at: http://labs.eeb.utoronto.ca/barrett/ KIRSTEN PRIOR is a community ecologist whose research combines field-based manipulative experiments and observational approaches in the natural experiments presented by invasions to investigate questions such as the role of enemy release in invasion success and the effect of co-introduced mutualists in facilitating invasions. Her current research examines the mechanisms that contribute to the stability of ant-plant mutualisms in east African savannas. She received her Ph.D. from the University of Notre Dame and was formerly the EEB departmental postdoctoral fellow at the University of Toronto. She is now a postdoctoral researcher in the Department of Biology at the University of Florida. More information on Dr. Prior's research may be found at: https://sites.google.com/site/kirstenmprior/contact/home

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ABSTRACTS

Please note: Presenting author is indicated by asterisk (*)

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Abstract Multi-trophic interactions determine competition and abundance among exotic and

native plants in communities P.M. Antunes*1, V. Reininger1, L. Martinez-Garcia1, L. Sanderson1, and A. Dukes1

1Department of Biology, Algoma University, Sault Ste. Marie, ON, Canada A major goal in ecology is to understand why some plants are more abundant than others in communities. At the present time this is particularly important given that more than 20% of the flora of North America consists of exotic species, many of which dominate natural systems. Despite their recognized importance, little is known about how plant-fungal interactions determine plant relative abundance and competitive interactions in natural communities. We characterized the plant community structure of an old-field in Northern Ontario and conducted a series of complementary field and greenhouse studies to address the following questions: 1. How do exotics and native plants in the community alter the below ground fungal community, and can these alterations help explain invasion success? 2. How does the presence of a fungal endophyte specific to an exotic grass affect the competitive responses of its host with exotic and native species, and how does it affect below ground mutualistic and antagonistic symbiotic relationships among co-existing plants? We found that fungal communities below ground are more structured among rare native species than among exotics, suggesting the importance of specialists. The endophyte was key to the competitive success of its host and this included reducing enemy attack when growing together with other plants. Taken together our results indicate that plant-fungal interactions may be instrumental in explaining plant success in communities and that exotic species represent a homogenizing force on plant-associated microbial communities whose long-term consequences are poorly understood.

11

Abstract Thirty to fifty years of change in upland forest understory communities of southern Ontario, west of Lake Ontario M. Apostoli*¹, T. Carleton¹, and P. Maycock² ¹ The Faculty of Forestry, University of Toronto, Toronto, ON, Canada ² Department of Biology, University of Toronto at Mississauga, Mississauga, ON, Canada Resurveys of forest understory communities provide valuable information of changes in species composition over time, and suggest how species respond to environmental change. Findings from such research can help guide the efforts to conserve forests, or to restore them to conditions similar to before settlement. This current project reports the results from 2011-2012 resurveys of 64 upland forest stands in western Lake Ontario, ranging from the Niagara Escarpment to Mississauga, that were first surveyed between 1956 and 1986. Multivariate ordination indicates that understory composition is characterized by topography and location, with talus slope stands experiencing the least magnitude of change with passing time. Larger magnitudes of change were observed in stands located in urban areas and escarpment stands that suggest progressive species homogeneity across these sites. Alternatively, a PCA of paired species differences between stanzas showed similar patterns of change to species composition and abundance grouped by talus stands, other escarpment stands, and urban stands over time. The significant increase of garlic mustard (Alliaria petiolata), the exotic invasive understory plant, was ubiquitous across all three groupings (by 30-65%). A CCA of species data with 46 environmental and disturbance variables suggest that forest management, trampling, and fragmentation contribute to present day species composition in urban and other escarpment stands. Whereas, wind-throw and natural flooding appear to influence species composition in talus slope stands. The results of this project suggest biotic homogenization through species invasion, and other disturbances related to human influences have changed understory species composition in this region over time.

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Abstract A tale of two invaders: lessons from ecological assessments of native and introduced Phragmites and garlic mustard Bernd Blossey*1, Victoria Nuzzo2, Andrea Dávalos1, Laura Martin1 and Jill Cohen1

1Department of Natural Resources, Cornell University, Ithaca, NY 14853, USA 2Natural Area Consultants, 1 West Hill School Road, Richford, NY 13835, USA For the past 16 years we have assessed ecological impacts of two major invaders in forests (Alliaria petiolata, garlic mustard) and wetlands (native and introduced Phragmites australis, common reed) in preparations for potential releases of biocontrol agents. Our results, often using brown food webs and amphibians, held a number of ecological surprises. First, garlic mustard invasions follow earthworm invasions and the plant is a symptom and not a driver of negative ecosystem changes in forests. In particular, negative effects are a consequence of elevated white-tailed deer populations and not a response to garlic mustard. Furthermore, we documented widespread declines of garlic mustard as a function of negative soil feedbacks throughout the Northeast. Our evaluations of effects of native and introduced Phragmites on native ecosystems show that origin (native or introduced) was rarely a factor explaining effects on amphibians. Instead differences in chemistry between populations, native or introduced, drive effects of Phragmites. What remains troublesome is the high competitive ability of introduced Phragmites eliminating many diverse wetland plants across the region. While we no longer advocate for release of biocontrol agents for garlic mustard, we have high hope for release of specific agents to replace the expensive ($4 million annually) and unsuccessful chemical management currently dominating Phragmites management in North America.

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Abstract

Misconceptions about classical biological control of weeds

U. Schaffner1, H.L. Hinz1, and R. Bourchier*2

1CABI, Delémont, Switzerland 2Agriculture and Agri-Food Canada, Lethbridge, AB, Canada

Modern classical biological control of exotic weeds aims to mitigate the negative impact of invasive weeds on biodiversity, human welfare, and economy. It implies the deliberate release of specialist natural enemies from the weed’s native range to reduce the abundance of a weed in its introduced range below an ecological or economic threshold. Assessing the likelihood of non-target effects by a potential biological control agent when introduced into a new range is one of the fundamental challenges of pre-release studies in biological control projects. The long history of pre-release studies in biological weed control has significantly contributed to the development of environmental risk assessment procedures. Yet, despite its wide application across the world, discussions about the risks involved in classical biological weed control are often dominated by misunderstandings and misconceptions. By addressing some of these misconceptions, we will elaborate key questions that should be raised in public and scientific debates on the potential risks and benefits of releasing exotic organisms to control exotic invasive weeds.

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Abstract Release of Hypena opulenta for biological control of dog-strangling vine (Vincetoxicum) in North America Rob Bourchier*1, Aaron Weed2, Lisa Tewksbury3, Naomi Cappuccino4, Sandy Smith5, André Gassmann6, and Richard Casagrande3

1Agriculture and AgriFood Canada-Lethbridge Research Centre, Alberta, Canada 2Biological Sciences, Dartmouth College, Hanover, NH 03755 3Department of Plant Sciences and Entomology, University of Rhodes Island, Kingston, USA 4Dept. of Biology Carleton University, Ottawa, Ontario, Canada 5Faculty of Forestry, University of Toronto, Ontario, Canada 6CABI Europe-Switzerland, CH-2800 Delémont, Switzerland Two species of European swallow-wort, Vincetoxicum nigrum and Vincetoxicum rossicum, have become invasive in North America, where there are no effective natural enemies available to suppress populations and deter further spread. Hypena opulenta is a multivoltine leaf-feeding moth and one of five European insects that are being considered as potential biocontrol agents for swallow-worts. A petition for the release of H. opulenta in the eastern US and in southern Ontario was submitted to regulatory authorities in December 2011. The first release of H. opulenta was made near Ottawa, Canada in Sept. 2013. Late-instar larvae which had been reared under short day photoperiod to diapause as pupae were released to assess overwintering success. The initial release site was in a stand of V. rossicum on a forest edge to enable evaluation of H. opulenta’s preference and impact in both sun and shade. In spring 2014, the emergence of test pupae stored in the lab over the winter, from same cohort as the released larvae was greater than 50%. We will report on the status of this first release, as well as additional releases using non-diapausing early-instar H. opulenta, conducted under similar habitat conditions during the summer of 2014. The first US release is intended for Naushon Island in Massachusetts in 2014, pending a US release permit.

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Abstract Potential biocontrol introductions against exotic Phragmites australis in North America Richard Casagrande*1, Bernd Blossey2, Lisa Tewksbury1, and Patrick Häfliger3

1 Department of Plant Sciences and Entomology, University of Rhode Island, Kingston, USA 2 Department of Natural Resources, Cornell University, Ithaca NY, USA 3 CABI Europe-Switzerland, CH-2800 Delémont, Switzerland Over the past 15 years we have surveyed and evaluated existing insect herbivores of Phragmites australis in North America in preparation for a program of classical biological control of the exotic subspecies of this plant. Most of the existing insects are relatively recent introductions and some show differential attack rates between native and exotic P. australis, but none have demonstrated potential for substantially reducing populations of these plants. Accordingly, we have focused on European natural enemies for potential introduction. Of the nine priority insects found at 15 survey sites in Europe, we have narrowed our emphasis to the two most promising. Laboratory studies in Rhode Island and Switzerland show the noctuid moths Archanara geminipuncta and A. neurica to be host-specific to P. australis in no-choice lab tests. Common garden behavioral tests at CABI in Switzerland show a marked preference for North American exotic P. australis over the native North American subspecies. The tendency of native North American P. australis to drop its leaves (and any eggs laid on them) for the winter further minimizes potential adverse impacts of these Archanara species on the native subspecies. We are preparing a petition to release both A. geminipuncta and A. neurica in North America.

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Abstract The Role of Invasive Earthworms in Forest Community Seed Predation

C Cassin*1 and PM Kotanen1 1Ecology and Evolutionary Biology, University of Toronto, Toronto, ON, Canada Soil seedbanks play a vital role in forest plant communities, having long been viewed as a safety refuge for seeds that are vulnerable to aboveground seed predators. This study provides evidence that seeds which occupy the soil seedbanks may be subject to previously underestimated rates of granivory by a common species of invasive earthworm, Lumbricus terrestris. We report that nearly 55% of seeds from 6 ecologically meaningful forest species were either digested or buried below a germinable depth when in the presence of earthworms in a microcosm experiment. L. terrestris was also found to preferentially remove certain species of seed over others, for instance smaller sized seeds were often removed in higher abundances than larger sized seeds. The common forest invader Garlic Mustard, Alliaria petiolata, was subject to the highest removal rates in this study, as nearly 90% of seeds were effectively destroyed by earthworms.

In contrast, results from a field exclusion experiment indicate that seed predation by earthworms often may be eclipsed by rodent predation under natural conditions. Still, while seed predation by rodents was high, earthworms produced a small but measurable incremental effect, and exhibited different seed preferences. These findings suggest that although rodents are the main driver of seed predation, earthworms may have the potential to act as an additional layer of ecological filter, and potentially further influence the species composition of future forest plant communities by selectively targeting certain seeds over others. Although the effects may be small, the application of these findings may prove useful to management of forests where threat of earthworm invasion exists.

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Abstract Main drivers of invasibility of managed boreal and northern temperate forests F. Wayne Bell1, Jennifer Dacosta*1, Pedro M. Antunes2, Isabelle Aubin3, Shelley Hunt4, Mahadev Sharma1, and Steven G. Newmaster5

1Ontario Forest Research Institute, Ontario Ministry of Natural Resources, 1235 Queen St. E., Sault Ste. Marie, ON, Canada P6A 2E5 2Department of Biology, Algoma University, 1520 Queen Street E., Sault Ste. Marie, ON, Canada, P6A 2G4 3Natural Resources Canada, Canadian Forest Service, Great Lakes Forestry Centre, 1219 Queen St. East, Sault Ste. Marie, ON, Canada P6A 2E5 4School of Environmental Sciences, University of Guelph, 50 Stone Road East, Guelph, ON, Canada N1G 2W1 5Centre for Biodiversity Genomics, Biodiversity Institute of Ontario, University of Guelph, Guelph, ON, Canada N1G 2W1 Even though invasive species are among the top factors contributing to ecosystem change globally, investigations of the invasibility of boreal and northern temperate forest ecosystems in North America are scarce. Here we used the NEBIE plot network (NEBIE stands for natural disturbances and extensive, basic, intensive and elite silviculture intensities), consisting of field sites across different forest types to show that northern temperate and boreal forests are invasible and that mixedwood forests seem to be more invasible than northern temperate hardwood or boreal conifer forests. Twenty-seven non-native plant species were observed, of which 18 belonged to the Asteraceae, Poaceae, and Fabaceae families. Our results on non-native species richness provide support for the intermediate disturbance hypothesis (IDH) and the propagule pressure and abiotic and biotic conditions (PAB) framework. Response surface analyses indicated that non-native species richness peaked at intermediate levels of silvicultural intensity. Regression and partial correlation analyses suggested that climate accounted for 47.4% of the variation in non-native species richness in northern temperate and boreal forests while disturbance effects accounted for 34.6% (represented by forest canopy structure – 19.6%, forest floor structure – 2.3%, and relative herbicide use – 12.7%). We conclude that the PAB framework provides a promising approach for accounting for the differences in invasibility of northern temperate and boreal forests.

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Abstract Plant-soil feedbacks along an invasion chronosequence Nicola J. Day*1,2, Pedro M. Antunes2,3 & Kari E. Dunfield1

1School of Environmental Sciences, University of Guelph, 50 Stone Road East, Guelph, Ontario N1G 2W1, Canada 2Invasive Species Research Institute, 1520 Queen Street East, Sault Ste. Marie, Ontario P6A 2G4, Canada 3Department of Biology, Algoma University, 1520 Queen Street East, Sault Ste. Marie, Ontario P6A 2G4, Canada

Plants alter soil microbial communities and in turn these influence plant growth, termed plant-soil feedbacks. Positive/negative feedback occurs when a given plant species has greater/smaller fitness in home versus away soil (i.e., “trained” by another plant species). Positive/negative feedback can be due to a net balance between mutualists/pathogens. Exotic invasive plant species commonly show positive feedback in their invaded ranges and negative feedback in their native ranges, purportedly due to enemy release. However, broad scale studies have suggested negative feedback may increase in exotic invasive species over time, which is thought to be a result of the local enemies adapting to the novel plant. We collected soil across an invasion chronosequence to investigate temporal changes in plant-soil feedbacks and root-associated fungal communities in a highly invasive exotic plant in eastern North America, Vincetoxicum rossicum (Apocynaceae). We hypothesized that plants grown in soil from recently invaded sites (<12 years) would demonstrate positive feedback, but feedback would decrease with invasion time (50-100 years). Vincetoxicum rossicum was grown from seeds in a glasshouse study. Contrary to our hypothesis, plants grown in soil from recently invaded sites had lower shoot biomass than those in soil from at least 100 year old invaded soil. Several known fungal pathogens were detected in the roots of V. rossicum. However, their degree of specialization on this plant species is unknown. Our data shows that more than 100 years of invasion does not appear to have been sufficient for root enemies to cause declines in this exotic invasive plant.

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Abstract Challenges and opportunities in managing invasive species Dilhari Fernando* Executive Director, Invasive Species Centre It is widely accepted that invasive species -- whether terrestrial or aquatic – pose environmental, economic and societal threats across Canada and can cause irreversible harm on the landscape. However, there is no one entity in government or in the private, academic or NGO sectors that is solely responsible for invasive species prevention, detection, control and management, and consequently, the work of many need to come together for any meaningful effort to combat invasive species. This presentation will look at the unique characteristics of invasive species management in Canada, and how jurisdictional cracks have created both challenges and opportunities for invasive species management. The presentation will focus on key levers and tools that are at the disposal of those managing invasive species, the need for building better bridges between science, policy and outreach/communications, and the need for leadership to bring invasive species issues to the forefront among decision makers and the public.

20

Abstract The influence of plant phylogenetic and functional relatedness on plant-soil feedbacks Connor Fitzpatrick*1, Laura Gehant2, Peter Kotanen1, Marc Johnson1

1Department of Biology, University of Toronto Mississauga, Mississauga, Ontario L5L 1C6, Canada 2Unité Mixte de Recherche Agroécologie, AgroSup, Dijon, 21000, France Soil microbes play an important role in plant ecology by altering plant competitive ability and resource requirements. We know that variation in functional traits (root chemistry, photosynthetic rate, etc.), among plant species can shape soil microbial communities. The unique community harbored by one plant species can limit or promote the growth of another species. These plant-soil feedbacks are common in nature and have been implicated in the maintenance of diversity and succession in plant communities. Despite their importance in fundamental processes such as plant coexistence and community assembly, we lack an understanding of the causal factors driving the outcome of plant-soil feedbacks. Here we grew 8 focal plant species in soils previously conditioned by 50 other plant species representing a spectrum of phylogenetic and functional similarity between focal and soil-conditioning plant species. We found large differences in the response of focal plants to soils conditioned by other plant species and in the response of individual focal plant species to a given soil treatment. Further our results show that the functional relatedness among focal and soil-conditioning species is an important predictor of the magnitude of their plant-soil feedback.

21

Abstract Origins and impacts of emerging pathogens in invaded plant communities S Luke Flory*1, Kerry Bohl Stricker1, Philip F Harmon2, Keith Clay3 and Erica M Goss2

1Agronomy Department, University of Florida, Gainesville, FL 2Plant Pathology Department, University of Florida, Gainesville, FL 3Department of Biology, Indiana University, Bloomington, IN

Introduced species often escape from their enemies, including herbivores and pathogens, when they arrive in a new range, resulting in widespread invasions. However, such dynamics may only be temporary and several studies suggest that enemies may accumulate on introduced species over time. Over the long term, emergent pathogens may cause declines in invasive species and their impacts, have little ecological consequence owing to tolerance, or enhance invasions through spillback to native species and apparent competition with the invader. We are investigating patterns of pathogen emergence and accumulation using the highly problematic invasive grass Microstegium vimineum (stiltgrass) in the eastern United States as a model system. In a biogeographic survey across a chronosequence of more than 80 sites in 18 US states we found multiple, novel fungal pathogens from the Bipolaris group on both Microstegium and native grasses, many of which cause disease on important crop species. An important predictor of disease incidence on Microstegium populations across the sites was the age of the invasive population, suggesting accumulation of pathogens over time. In a field experiment across four sites in West Virginia we found that suppression of pathogens using fungicides increased Microstegium seed head production by up to 89% on average, demonstrating potential population level effects of pathogen infection. Additional field experiments and modeling will reveal if emergence and accumulation of pathogens will cause declines in invasive populations or exacerbate the effects of invasions over the long-term.

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Abstract Extreme differences in population structure and genetic diversity for three invasive congeners: knotweeds in western North America John F. Gaskin*1, Mark Schwarzländer2, Fritzi S. Grevstad3, Marijka A. Haverhals2, Robert S. Bourchier4, Timothy W. Miller5

1 USDA Agricultural Research Service, 1500 N. Central Avenue, Sidney, MT 59270, USA 2 Department of Plant, Soil and Entomological Sciences, University of Idaho, Moscow, ID 83844, USA 3Department of Botany and Plant Pathology, Oregon State University, Corvallis, OR 97331, USA

4Agriculture and AgriFood Canada-Lethbridge Research Centre, 5403-1st Avenue South, Lethbridge AB CANADA T1J 4B1 5 Washington State University, Northwestern Washington Research and Extension Center, 16650 State Route 536, Mount Vernon, WA 98273, USA Japanese, giant, and the hybrid Bohemian knotweeds (Fallopia japonica, F. sachalinensis and F. x bohemica) have invaded the western USA and Canada, as well as other regions of the world. The distribution of these taxa in western North America, and their mode of invasion, is relatively unresolved. Using Amplified Fragment Length Polymorphisms of 858 plants from 131 populations from British Columbia to California to South Dakota, we determined that Bohemian knotweed was the most common taxon (71% of all plants). This result is in contrast to earlier reports of F. x bohemica being uncommon or non-existent in the USA, and also differs from the European invasion where it is rarer. Japanese knotweed was monotypic, while giant knotweed and Bohemian knotweed were genetically diverse. Our genetic data suggest that Japanese knotweed in western North America spreads exclusively by vegetative reproduction. Giant knotweed populations were mostly monotypic, with most containing distinct genotypes, suggesting local spread by vegetative propagules, whereas Bohemian knotweed spreads by both seed and vegetative propagules, over both long and short distances. The high relative abundance and genetic diversity of Bohemian knotweed make it a priority for control in North America.

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Abstract The evolution of species invasion potential R.M. Germain* and B. Gilbert Department of Ecology & Evolutionary Biology, University of Toronto, Toronto, ON, Canada In Mediterranean-climate regions, ~20% of all plant species are non-native, yet only a small fraction of those is considered invasive. Theories attempting to explain this observed variation in the impacts of non-native species tend to be founded on “special case” examples rather than generalizable rules, and have yet to be validating experimentally in many cases. Here, we tested the hypothesis that non-native species evolve greater differences in competitive ability, rather than novel resource use (i.e., niche partitioning, the mechanism proposed by previous work). To test this specific general mechanism, we parameterized population models with empirical data collected from a greenhouse experiment with Mediterranean annual plant species. Thirty species were selected across an angiosperm phylogeny and differed in biogeographic origin (California [n = 20] or Spain [n = 10]). The species were grown in pairwise competition according to two treatments: (1) native competitors, with both species native to California, or (2) non-native competitors, with each species native to either California or Spain. We found evidence that differences in competitive ability (P < 0.05), but not niche partitioning, increased with phylogenetic distance between non-native competitors. On average, focal species native to California reduced seed production by 43% when grown with non-native versus native competitors. These results suggest distantly related non-native species are predicted to have the greatest impacts on native diversity, due to evolved differences in competitive ability.

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Abstract Bloodroot (Sanguinaria canadensis) as a deterrent to the spread of invasive garlic mustard (Alliaria petiolata) G.L. Govers*1, M.A. Smith2, and S.D. Murphy1

1 Department of Environment & Resource Studies, University of Waterloo, Waterloo, ON, Canada 2 Department of Integrative Biology, University of Guelph, Guelph, ON, Canada The invasion of garlic mustard (Alliaria petiolata) has been devastating to the understory species of deciduous forests of eastern North America due to its chemical suppression of mycorrhizal fungi symbiosis. Following a previous study finding that high densities of the spring ephemeral bloodroot (Sanguinaria canadensis) are able to inhibit the nearby establishment of A. petiolata, further investigation was commenced as to the viability of its use in management. A seed germination bioassay was conducted, exposing A. petiolata seeds to sanguinarine, the predominant root exudate of S. canadensis, to determine if seed germination or viability are altered by its presence. Following scarification and treatment with a 10-3 M gibberellic acid solution, seeds were exposed to 2 mL treatments of sanguinarine solution [0(control), 100 or 200 µg/mL] twice a week. After 3 weeks, light levels were reduced to emulate canopy closure. Seeds remaining ungerminated 2 weeks after this time were then tested for viability using tetrazolium chloride. A significant reduction in germination was achieved. As S. canadensis seeds are ant dispersed, the alteration of the ant community by A. petiolata is also an important consideration if self-sustaining deterrence is to be achieved. Four sites in the Waterloo-Guelph region were selected - two fragmented, urban woodlots and two larger, semi-rural protected areas. Using pitfall traps and Winkler litter extraction, it was found that seed-dispersing ant species presence was not significantly altered by garlic mustard presence. These results suggest that bloodroot supplementation may be a viable management strategy to deterring garlic mustard invasion.

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Abstract Effects of a potentially invasive Miscanthus grass on local vegetation communities and soil seed bank H.A. Hager*1, L.D. Quinn2, and J.A. Newman1

1School of Environmental Sciences, University of Guelph, Guelph, ON, Canada 2Energy Biosciences Institute, University of Illinois Urbana-Champaign, Urbana, IL, USA Three species of Asian perennial Miscanthus grass are now widely cultivated in North America for horticultural (ornamental) and agricultural (bioenergy) purposes. One of these species (M. sinensis) has escaped cultivation and become invasive in the northeastern United States. Our objective was to determine the extent of escape and potential effects on local vegetation of Miscanthus species in Ontario. We located escaped and spreading populations by consulting local experts and searching targeted areas. We then surveyed 10 of these populations to characterize the vegetation communities and soil seed bank as compared to local, uninvaded vegetation. The vast majority of current escapes in Ontario are M. sacchariflorus. Univariate ANOVA indicated that plots with M. sacchariflorus supported very few other vegetation species and had lower abundance, richness, and diversity in both the local vegetation community and soil seed bank than did plots without M. sacchariflorus. In addition, plots with M. sacchariflorus had more live and dead standing biomass, taller vegetation, and greater litter biomass, leading to decreased light penetration to the soil surface than did plots without M. sacchariflorus. Multivariate ANOVA using partial canonical correspondence analysis indicated that M. sacchariflorus had a greater effect on vegetation community composition than it did on the soil seed bank composition. Given that M. sinensis and M. × giganteus are currently cultivated more extensively than M. sacchariflorus, our results suggest that monitoring and management efforts should be implemented to minimize their risk of escape into surrounding local and natural vegetation communities.

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Abstract A stochastic bioeconomic invasive species management system Ed Hanna*1 1DSS Management Consultants Inc., Pickering, ON, L1V 3E4 Invasive species management involves ongoing decisions regarding the most economically efficient deployment of limited resources under conditions of high uncertainty in a time-sensitive setting. Decision-makers must choose from among many alternative courses of action; each involving complex ecological, economic and social dimensions with large upside and downside risks. The literature shows clearly that intuitive decision-making under such conditions is unreliable and decisions are significantly improved when supported by systematic, quantitative analyses of the available choices. This presentation describes a stochastic, GIS-based, bioeconomic invasive species management system (ISMSS) developed to assist in making these difficult decisions. ISMSS includes spatially discrete routines representing the ecological stages of invasive species infection (i.e., introduction, establishment, spread and senescence). For each temporal and spatial unit, management interventions (e.g., prevention, detection, eradication, control) can be deployed; each having its own expected effectiveness and costs. Ecological damage functions forecast biophysical and economic losses that are dependent on the extent and density of the invasive species population. A Monte Carlo analysis feature combines uncertainty/error ranges for all system parameters to calculate the upside and downside risks for each alternative. ISMSS allows a wide range of management alternatives to be evaluated rapidly and consistently. Its value for integrating and applying diverse invasive species data and knowledge for making ongoing strategic and operational management decisions will be explained. The presentation will conclude with a discussion of how to make the best use of ISMSS for reducing the risk of future ecological and economic damages from invasive species.

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Abstract Will any of the potential biological control agents against garlic mustard ever get a green card? H.L. Hinz*1, E. Gerber1, J. Katovich2, and R. Becker3

1CABI, Delémont, Switzerland 2 University of Minnesota, Department of Agronomy and Plant Genetics, St. Paul, MN, USA 3University of Minnesota, Agronomy and Plant Genetics, St. Paul, MN, USA In 1998, a biological control project was started for garlic mustard (Alliaria petiolata; Brassicaceae) at CABI in Switzerland. Four weevils, all in the genus Ceutorhynchus were prioritized for in depth studies. A demographic model predicted that the root-crown mining C. scrobicollis would be the most successful individual agent. Based on tests with 76 plant taxa, a petition for field release was submitted to the USDA, APHIS Technical Advisory Group (TAG) in 2006. Since then, the petition has been reviewed twice. Both times, field release was recommended by the majority of reviewers. Concerns by reviewers not in favour of release were partly based on insufficient coverage of test species due to constant changes in the tribal arrangement within the Brassicaceae. We were also requested to test additional native North American species, in particular threatened and endangered (T&E) species. Additional tests are currently being conducted. Host-specificity tests with the seed feeding weevil C. constrictus have so far covered 79 different taxa, 59 in the family Brassicaceae. Complete adult development occurred on two commercially grown species, Brassica nigra (black mustard) and B. juncea (brown mustard) under no-choice conditions. However, several open-field tests have shown that the two species are not attacked under natural field conditions. Host-specificity results for both agents will be discussed in view of the current regulatory climate in the USA and Canada.

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Abstract Early detection and distribution mapping system Ontario A. Kirkpatrick*1 1Ontario Federation of Anglers and Hunters, Peterborough, ON, Canada In Ontario, there are numerous agencies and monitoring programs in place that collect information and/or identify the distribution of invasive species. Monitoring programs generate large quantities of data, often covering a wide geographic area, multiple species, and lengthy time periods. The early detection and rapid response of these invasive species in Ontario is essential in preventing their introduction, establishment, or spread. The Ontario Federation of Anglers and Hunters, in partnership with the Ontario Ministry of Natural Resources, the Invasive Species Centre and the University of Georgia Centre for Invasive Species and Ecosystem Health has launched the Early Detection and Distribution mapping System (EDDMapS) for Ontario. The web-based mapping system is fast and easy to use, requiring no knowledge of GIS. EDDMapS Ontario also brings the power of reporting invasive species to your mobile device. The new EDDMapS App builds on the EDDMapS web online system. Using your mobile device, you can make a report, search data and distribution maps, get email alerts and learn about more than 150 invasive species. The App helps early detection and rapid response efforts, maximizing the effectiveness and accessibility of invasive species observations with a network of expert verifiers.

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Abstract Effects of the invasive vine Vincetoxicum rossicum on ecosystem multi-functionality S.W. Livingstone*1 1Department of Physical and Environmental Sciences, University of Toronto-Scarborough, ON, Canada Human-caused species invasions are widely recognized as not only having significant economic impacts, but also drastically reducing diversity and altering ecosystem function. Ontario’s Rouge Park contains variable abundance of Dog-strangling vine (Vincetoxicum rossicum), an aggressive plant invader from Eurasia. Variable dominance of V. rossicum results in a diversity gradient throughout the Park with some sites being virtual monocultures, others showing partial invasion, and others as of yet un-invaded. As a component of my dissertation work, I am examining how the relative abundance of the V. rossicum affects multiple ecosystem functions & services in meadow communities (decomposition rates, pollinator support, nutrient availability, primary production). This work is preceding the release of a biological control agent for V. rossicum, Hypena opulenta, and will provide baseline data that will be used to assess the effectiveness of H. opulenta as well as ecosystem-level impacts of this biological control effort.

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Abstract Pollen allelopathy: Taraxacum officinale pollen depresses seed set of montane wildflowers Deirdre Loughnan*1, James D. Thomson 1,2, Jane E. Ogilvie 1,2 and Benjamin Gilbert1

1 Department of Ecology and Evolutionary Biology, University of Toronto, 25 Harbord Street, Toronto, ON, M5S 3G5, Canada

2 Rocky Mountain Biological Laboratory, Post Office Box 519, Crested Butte, CO 81224-0519, USA

Plant species that share pollinators can suffer from interspecific pollen deposition. Male reproductive success is inevitably reduced by the loss of pollen to flowers of another species. Female reproductive success can be affected by reduced stigmatic area or, more strongly, through allelopathic effects by which the admixture of some foreign pollen reduces seed or fruit set. We tested for allelopathic effects of Taraxacum officinale (Asteracaeae) pollen on the seed set of montane wildflowers Erythronium grandiflorum (Liliaceae) and Erysimum capitatum (Brassicaceae), by hand-pollinating plants with pollen mixtures. Taraxacum is a common invasive species, which produces allelopathic chemicals in its root and vegetative tissue, making it a likely candidate for pollen allelopathy. Flowers of both species produced fewer well-developed seeds when pollinated with pollen mixtures containing Taraxacum pollen. The pollen-allelopathic potential of weedy dandelion may add to its ability to disrupt communities that it invades.

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Abstract Adaptive potential in invasive ragweed B.V. McGoey*1 and J.R. Stinchcombe1 1Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, ON, Canada Anthropogenic change, including the movements of species to novel locations, has immense ecological and economic impacts. Introduced species can also be thought of as unplanned experiments, which can be opportunistically investigated to advance our understanding of contemporary evolution. Characterizing available genetic variation is important for determining the ability of a given population to adapt, and for predicting which traits will evolve. For outcrossing species, the relevant measure is additive genetic variance. Despite this importance, there is a dearth of comparisons of the evolutionary capacities of invasive and native populations. The novelty of my work is in addressing this gap in the literature and to examine an invasive plant species from a quantitative genetics perspective. My goals are to characterize and compare the additive genetic variance of native and introduced populations for key traits likely to influence invasion success and to examine correlations between traits, which could accelerate or constrain evolutionary responses. To achieve these goals, I developed an innovative single plant chamber system for controlled crosses in wind-pollinated plants, and used a half-sibling crossing design to estimate the additive genetic variance of each population for ecologically important traits. My focal species, Ambrosia artemisiifolia (ragweed), is a globally invasive species, with economic, ecological and human health impacts.

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Abstract Resistance or susceptibility? Invader interactions between garlic mustard (Alliaria petiolata) and the common nightcrawler earthworm (Lumbricus terrestris) in Ontario forests Michael J. McTavish*1, Stephen D. Murphy1, and Sandy Smith2

1Department of Environment & Resource Studies, University of Waterloo, Waterloo, ON, Canada 2Faculty of Forestry, University of Toronto, Toronto, ON, Canada The invasion patterns of exotic species can be altered by interactions with co-occurring invaders. It has been suggested that the invasion of one of North America’s most prominent invasive plant species – garlic mustard (Alliaria petiolata) – is facilitated by the actions of another exotic invasive species – the common nightcrawler earthworm (Lumbricus terrestris). This hypothesis has received limited experimental validation and has only considered effects of the two species on mycorrhizae, ignoring our growing awareness of earthworms as granivores and seed dispersers. The primary research question of this project is: What is the net effect of L. terrestris on garlic mustard populations through interactions with garlic mustard seeds? Field surveys in Ontario, Canada were paired with mesocosm studies of earthworm-seed interactions. Although L. terrestris consumes large numbers of garlic mustard seeds, a considerable proportion survive gut passage. These egested seeds show evidence of seed coat damage but may also suffer from reduced or delayed germination. Additionally, garlic mustard seedling recruitment decreases dramatically with seed depth and L. terrestris appears to be responsible for the burial of a large number of surface-collected seeds. Many forests in eastern North America susceptible to garlic mustard invasion have already been colonized by exotic earthworms. Understanding whether these forests have a unique resistance or an increased susceptibility to garlic mustard invasion will be useful to guide more effective management efforts against future invasions. This case study example also contributes to our growing understanding of the ecological consequences of interactions between invasive species.

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Abstract Demographic matrix models of swallow-wort (dog-strangling vine, Vincetoxicum species) and projected agent impacts L.R. Milbrath*1, A.S. Davis2, and J. Biazzo1

1USDA-ARS, Robert W. Holley Center for Agriculture and Health, Ithaca, NY USA 2USDA-ARS, Global Change and Photosynthesis Research Unit, Urbana, IL USA Demographic matrix modeling of plant populations can be a powerful tool to identify key life stage transitions that contribute the most to population growth of an invasive plant and hence should be targeted for disruption. Therefore, this approach has the potential to guide the pre-release selection of effective biological control agents. We have parameterized a five life-stage matrix model for the swallow-wort (dog-strangling vine) biological control program. Pale swallow-wort, Vincetoxicum rossicum, and black swallow-wort, Vincetoxicum nigrum (Apocynaceae: Asclepiadoideae), are herbaceous, perennial, milkweed vines introduced from Europe. Both species are invading a variety of natural and managed habitats in eastern North America. Demographic transitions were measured in field studies for both swallow-wort species in open field and, for pale swallow-wort, forest habitats in New York State (N = six populations). Vital rates that were estimated included germination, survival, maturation (growth to the next life stage), and fecundity (viable seeds produced per plant). Elasticity analyses have identified several potentially important transitions for one or both species of swallow-wort: survival of vegetative juvenile, small flowering and large flowering plants; growth of seedlings, juveniles and small flowering plants to the next life stage; and reproduction of small and large flowering plants. In general, a combination of moderate to substantial reductions in survival, fecundity, and/or growth is needed for most populations to decrease in size. By incorporating available impact data of candidate biological control agents, it appears that a bivoltine defoliator may be promising for forest infestations of swallow-wort but not for most field infestations.

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Abstract Spatial variation in aboveground herbivory of native and exotic Asteraceae Krystal A. Nunes*1, Colin M. Cassin1, and Peter. M. Kotanen1

1Ecology and Evolutionary Biology, University of Toronto, Toronto, ON, Canada Damage by herbivores to their host plants often declines over a latitudinal gradient; however, most such studies have focussed on native species. Exotic plants often lose many of their enemies invading new regions, suggesting they might follow a different pattern than native relatives. To determine if similar patterns exist between damage rates of native and exotic species of Asteraceae, an 815 km latitudinal transect was sampled from agricultural southern Ontario to boreal James Bay. Herbivory was documented by quantifying leaf damage and attack by seed parasitizing insects. Number of shoots, plant height, number of flowers, and seed production were quantified as estimates of performance. Initial data suggest that (1) plants in southern Ontario are heavily damaged, (2) defoliation is greatly reduced at northern and isolated sites, and (3) seed herbivory shows great spatial variation related to land use type and population isolation. A focal species of this research is Canada thistle (Cirsium arvense), a Eurasian weed invasive across North America, for which biological control has been attempted. The most southerly and northerly sites exhibited high rates of seed herbivory, but the causal organism differed between these regions. Isolated mid-latitude populations showed little evidence of aboveground herbivory, likely because populations were very sparsely distributed. These results suggest that there is a critical host abundance required to support C. arvense's natural enemies, which are often absent from range margins and/or isolated sites.

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Abstract Invasive phragmites (Phragmites australis) monitoring and management Prabir Roy*1 1Ecosystem Scientist, Parks Canada, Midland, ON L4R 4K6 The invasive phragmites, Phragmites australis, is not only an ecological threat but also reduces the aesthetic value of properties. We are intensively monitoring to both prevent and minimize the impacts of invasive phragmites. We conducted a series of experiments to: (1) develop a monitoring tool based on remote sensing data (2) understand the environmental factors responsible for the invasion and expansion of phragmites in southern Georgian Bay, (3) assess the impact of phragmites on native plants and (4) evaluate the impact of cutting phragmites stems on patch growth. Preliminary remote sensing monitoring results indicated that the very small size of phragmites patches requires sub-meter resolution TerraSAR-X starring mode data. Wet organic disturbed soil is the most favorable habitat for phragmities invasion. Near-shore, large wetland areas where water can enter seasonally because of small changes in Great Lakes water depth, but the landscape has the ability to retain the water instead of completely draining, are more susceptible to rapid colonization. Invasive phragmites negatively impacts native species by replacing wetland macrophytes: sedges, bulrushes, and Canada bluejoint grass on the shoreline. Stem cutting inhibits the further increase of phragmites patch size and significantly reduces phragmites growth and density. These findings have important implications for monitoring, understanding the impact of phragmites, control measures, and ultimately the development of a management plan based at a landscape or ecosystem level.

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Abstract Adaptation to biocontrol? Testing for phenotypic divergence among populations of an invasive plant Michael Stastny1 and Risa Sargent*1 1Department of Biology, University of Ottawa, Ontario, Canada The introduction of a biological control agent has the potential to induce novel selection on populations of invasive plants. If such selection results in increased resistance or tolerance to herbivory, it has the potential to reduce the effectiveness of a biological control program. In order estimate whether purple loosestrife (Lythrum salicaria) growing in populations that have been exposed to different densities of the introduced herbivore Galerucella pusilla differ in their responses to herbivores, we gathered seed from 18 Ontario populations with a range of histories of exposure to this biological control agent. Replicates from 16 maternal lines were first grown in a greenhouse, where traits related to herbivore tolerance were measured on seedlings. Subsequently, 8 maternal lines were transplanted as seedlings into an existing Lythrum population west of Ottawa, ON, and exposed to ambient (moderate to high) levels of herbivory by Galerucella adults and larvae. In our greenhouse study, plants grown from populations with no Galerucella history tended to remain smaller and flower earlier than those from populations that had been exposed to the biocontrol agent. In the initial field season, Galerucella history did not predict feeding damage or plant size. Results from the second field season are forthcoming.

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Abstract Japanese knotweed biocontrol – a shaky start R. H. Shaw*1 R. Eschen2 and A. Brook1

1 CABI, Bakeham Lane, Egham, Surrey, TW20 9TY, UK 2 CABI, Rue des Grillons , CH-2800 Delémont, Switzerland Japanese knotweed is a serious weed in almost every region to which it has been introduced and the associated costs in time and money and to the receiving environments are very high indeed. A collaborative biocontrol programme between UK and North American researchers began in 2000 and culminated in the release of the specialist psyllid Aphalara itadori in England and Wales in 2010, and in 2013 the scientific review panels in Canada and the US recommended its release. Four years into the release process in the UK we are not yet celebrating success. The constraints to successful establishment are many and include the restrictions that have been placed upon this first ever release of a weed biocontrol agent in the EU as well as the long period of culturing of the psyllid under Japanese summer conditions. The progress of this pioneering project is reviewed and the next steps towards a successful conclusion are discussed. Europe is waking up to classical weed biocontrol partly because of the imminent EU Invasive Species Regulation and there is a need for a success to tip the balance. The current limited activity in this field in Europe is discussed in the light of likely successes.

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Abstract Demographic consequences of soil moisture variation for an invasive, hybridizing weed Z. Teitel*1 and L.G. Campbell1

1 Depatment of Chemistry and Biology, Ryerson University, Toronto, ON, Canada Cultivated plants are known to readily hybridize with their wild relatives, forming invasive populations that can become weedier than their parental phenotypes. With global climate change, increasingly variable precipitation may create new advantages for weeds in agricultural habitats. To assess the relative ability of new populations to grow and invade a new location, we compared the demography of wild radish (Raphanus raphanistrum) and crop-wild hybrid radish (Raphanus raphanistrum x Raphanus sativus) populations across a soil moisture gradient. Field populations of wild radish and F1 hybrid radish were established in 2012 and received one of four watering treatments over the 2012-13 field seasons. Weekly population censuses assessed the number of seedlings emerging, their rate of survival and eventual fecundity. Hybrid populations had higher λ than wild populations but λ did not differ across precipitation treatments. Fecundity represented the greatest contributions to λ and was the most elastic demographic parameter relative to other life history stages. Predicting the likelihood that a weedy genotype will successfully invade requires an understanding of its λ and compositional demographic transition rates relative to its competitors. This study better informs selective weed control by isolating the most effective life-history stage ‘choke point’ to suppress population growth.

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Participants

Last Name Given Name Affiliation

Addante Frank Ontario Ministry of Natural Resources

Antunes Pedro Algoma University

Apostoli Melissa University of Toronto

Barrett Spencer University of Toronto

Blossey Bernd Cornell University

Bourchier Rob Agriculture & AgriFood Canada

Cadotte Marc University of Toronto

Casagrande Richard University of Rhode Island

Cassin Colin University of Toronto Mississauga

Cox William County of Simcoe

Crowe Colleen University of Toronto

Dacosta Jennifer Ontario Ministry of Natural Resources

Day Nicola Algoma University

DiLeo Michelle University of Toronto Mississauga

Doll Kendrick Ontario Heritage Trust

Fernando Dilhari Invasive Species Centre

Fitzpatrick Connor University of Toronto Mississauga

Flory Luke University of Florida Gainesville

Fulthorpe Roberta University of Toronto Scarborough

Gaskin John USDA-ARS

Germain Rachel University of Toronto

Gibb Jennifer City of Toronto

Gilbert Ben University of Toronto

Govers Gwyneth University of Waterloo

Hager Heather University of Guelph

Hannna Ed DSS Management Consutants Inc.

Hinz Hariet CABI

Irvine Michael Ontario Ministry of Natural Resources

Johnston Emily Ontario Federation of Anglers and Hunters

Kirkpatrick Alison Ontario Federation of Anglers

Kotanen Peter University of Toronto Mississauga

Kucher Kile Michigan Department of Natural Resources

Livingstone Stuart University of Toronto

Loughnan Deirdre University of Toronto

MacDonald Francine Ontario Ministry of Natural Resources

MacIvor Scott York University

Martin Jessica Invasive Species Centre

McGoey Brechann University of Toronto

McTavish Michael University of Waterloo

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Milbrath Lindsay USDA-ARS

Newman Jonathan University of Guelph

Nunes Krystal University of Toronto Mississauga

Pope Carleigh rare Charitable Research Reserve

Prior Kirsten University of Florida

Puttock David Silv-Econ Ltd.

Raimbault Bev University of Waterloo

Roy Prabir K. Parks Canada

Ryan Kathleen Silv-Econ Ltd.

Sargent Risa University of Ottawa

Shaw Richard CABI

Smith Martin Niagara College Canada

Smith Sandy University of Toronto

Sobek-Swant Stephanie rare Charitable Research Reserve

Tangora Sue Michigan Department of Natural Resources

Teitel Zachary Ryerson University

Thomas Cynthia Environmental Health & Safety

Thomsen Christina University of Ottawa

Wagner Helene University of Toronto

Watkins Dianne University of Waterloo

Xing Tim Carleton University

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