Biol Invasions (2010) 12:1967–1999 DOI 10.1007/s10530-009-9600-7

ORIGINAL PAPER

Should we care about purple loosestrife? The history of an invasive plant in North America

Claude Lavoie

Received: 7 November 2008 / Accepted: 2 October 2009 / Published online: 20 October 2009 © Springer Science+Business Media B.V. 2009

Abstract Purple loosestrife (Lythrum salicaria L., Introduction Lythraceae) is considered one of the worst invasive plant species in the world. In this paper, I reconstruct With the globalization of trade and the improvement how purple loosestrife quickly became, after a long in modes of transportation, biological invaders are (150 years) period of indifference, the persona non expected to become increasingly numerous and grata of North American wetlands. I then compare harmful to the ecosystems and the economies of a the portrayal of the species in newspapers (907 large number of countries (Perrings et al. 2005; articles) to that supported by the scientific literature McCullough et al. 2006; Westphal et al. 2008). It is (38 peer-review papers). The depiction of purple therefore crucial to conduct studies on invasive loosestrife in scientific studies (lacking definition) is plants and animals to rapidly identify the species far removed from that in newspapers (alarming). with the greatest impact, as the first step toward the Some native species likely suffer from an invasion, development of appropriate control measures. but stating that this plant has large negative impacts Nearly 900 invasive species were studied by ecol­ on wetlands is probably exaggerated. If purple ogists between 1980 and 2006; plants and insects loosestrife is not a primary cause of extinction or a accounted for two-thirds of the taxa studied. How­ major contributor to the decline of other species, but ever, some species have been studied far more than is instead an indicator of anthropogenic disturbances, others, such as the zebra mussel (Dreissena poly­ the resources and efforts devoted to removing this morpha (Pallas), Dreissenidae) or the Argentine ant species might be better focused on more effective (Linepithema humile (Mayr), Formicidae). Purple means to protect wetlands against disturbances. loosestrife (Lythrum salicaria L., Lythraceae) is one of the five most intensively studied invasive species Keywords Biological control . (Pysˇek et al. 2008). This species is reputed to Invasive plant species . Lythrum salicaria . outcompete native plants, form monocultures in Media . Purple loosestrife . Wetland wetlands and degrade habitats for wildlife, espe­ cially amphibians and birds (Blossey et al. 2001; Brown et al. 2006). Purple loosestrife is considered one of the 100 worst invasive alien species in the C. Lavoie (&) world by the International Union for the Conserva­ ´ Ecole supe´rieure d’ame´nagement du territoire et de tion of Nature (Invasive Species Specialist Group de´veloppement re´gional, Universite´ Laval, Quebec City, QC G1V 0A6, Canada 2008); it ranks second on the Prioritized List of e-mail: [email protected] Invasive Alien Plants in Natural Habitats in 123 1968 C. Lavoie

Canada, which measures species with the most Purple loosestrife: from indifference to celebrity serious impact (Catling and Mitrow 2007). South of the Canadian border, purple loosestrife has been Purple loosestrife was probably introduced in North declared a noxious weed in 32 states (United States America both inadvertently and for horticulture. Department of Agriculture 2008). Purple loosestrife seeds were sold in American and Intriguingly, purple loosestrife was long ignored Canadian nurseries as early as 1829 (Mack 1991; prior to its rapid ascension to its current status. Purple Delisle et al. 2003), but the species was also likely loosestrife is not a newcomer to North America. introduced by ships dumping ballast (sand) contain­ Introduced at the beginning of the nineteenth century, ing seeds, or by raw wool or sheep imported from it was already invading hundreds of hectares of Europe and contaminated with seeds (Thompson wetlands in the 1930s. However, it was not until the et al. 1987). The oldest herbarium specimens of end of the 1980s that this plant attracted the attention purple loosestrife were collected in Massachusetts of ecologists and environmental managers. In the (1831), Pennsylvania (1852), British Columbia 1990s, purple loosestrife rapidly became the ‘‘icon of (1857), New York (1864) and Quebec (1865). The invasive exotics’’ (Washington Post, 16 Apr. 2005), species rapidly spread to reach most other states and not only for invasion ecologists, but also in the provinces between 1940 and 1985 (Stuckey 1980). popular press. Nationwide education campaigns were Abundant populations were reported in the Boston undertaken in the United States and Canada to area in 1921 (Knowlton and Deane 1921), in New prevent the sale of the species for horticulture, and York state south of the Adirondacks in 1924 (House millions of European beetles were released in nature 1924), and along the Hudson River valley in 1929 as a result of a major biological control program. (Torrey 1929). By the end of the 1990s and the beginning of the In Quebec, purple loosestrife spread along the St. 2000s, a debate began about whether purple loose- Lawrence River valley from 1923 to 1946 (Delisle strife had really had an impact on wildlife and the et al. 2003); massive infestations of marshes in the ecological functions of wetlands (Anderson 1995; 1930s and the 1940s were reported by Fernald (1938) Hager and McCoy 1998; Blossey 1999; Blossey et al. and Louis-Marie (1944). The Commune de la Baie du 2001). However, relatively few data existed at that Febvre, a floodplain near Lake St. Pierre (a widening time to support the assertions of either party (for or of the St. Lawrence River) used as pasture since the against a major impact). Since then, numerous studies beginning of the eighteenth century, was probably the attempting to detect the consequences of a purple largest and the most severely infested wetland in loosestrife invasion on wetland ecosystems have been Quebec during this period. The purple loosestrife published, shedding new light on the topic. This invasion was impressive (1,375 ha; Fig. 1), but even unique extensive research effort may answer ques­ there, at least 39 other vascular plant species tions on biological invasions that would likely be coexisted with the invader (Doyon 1953). Louis- unobtainable with other, less studied species. A Marie (1944) attempted to eradicate the plant, but review of these studies is therefore important to most trials (crushing, hand-pulling, harrowing, mow­ anyone concerned with invasive plants. In this paper, ing, fire) were unsuccessful. The spraying of herbi­ I reconstruct how purple loosestrife quickly became, cides (2.4-D) associated with the seeding of reed after a long (150 years) period of indifference, the canarygrass (Phalaris arundinacea L., Poaceae) was persona non grata of North American wetlands. I the only effective eradication method. This method then compare the portrayal of the species in news­ was used on 24 ha in 1951, but there is no indication papers to that supported by the scientific literature. In that it was repeated in subsequent years (Doyon particular, I examine whether the press accurately 1953). reported ecologists’ findings on the impact of this After the work of Louis-Marie (1944) and Doyon species on wetlands. I conclude with an analysis of (1953), the species was almost completely forgotten the consequences of focusing particular attention on by ecologists until the publication of a historical this invasive plant, and on the relevance of the reconstruction of the spread of the plant in North intensive efforts to control purple loosestrife in America by Stuckey (1980). This remarkable work Canada and the United States. presents an exhaustive survey of the historical 123 Should we care about purple loosestrife? 1969

North America. Lee (2002) documented the Canadian consequences of the publication of this report. The Canadian Wildlife Service initiated (1990–1991) an informal survey across the country to verify whether purple loosestrife was causing problems. Since most wetland managers suspected major impacts on wild­ life, a campaign was undertaken in collaboration with Ducks Unlimited Canada to alert the public to the perils this plant presented to natural habitats. The task was to ‘‘convince the public that behind the beauty was a beast’’ (Lee 2002, p. 255). In 1991, a brochure entitled Beautiful Killer was published and distrib­ uted coast-to-coast. In 1992, a new brochure was distributed, and a national workshop on the manage­ Fig. 1 A large purple loosestrife population at the Commune ment of the species took place. In 1993, a biological de la Baie du Febvre, a floodplain of the St. Lawrence River (Quebec), in 1951, just before the spraying of herbicides (from control program was initiated, and 1 year later, two Doyon 1953) television networks presented documentaries on pur­ ple loosestrife. According to Lee (2002), this cam­ paign against purple loosestrife was a real success: literature and herbarium specimens of purple loose- ‘‘The newspaper-style headlines dramatizing the strife collected throughout the United States and impact of this plant on wetlands left many uneasy Canada. It nevertheless contains a sentence that is and uncomfortable. But with the wisdom of hindsight, symptomatic of many later scientific reports on it is now possible to say ‘it worked!’ Phones began to purple loosestrife: ‘‘As the history of its spread in ring, interviews were sought and given, school and North America reveals, L. salicaria has the ability to community projects started’’ (p. 254). (…) eliminate other species in both natural and Indeed, purple loosestrife rapidly attracted the artificial wetland habitats’’ (p. 15). Unfortunately, attention of the popular press. According to the herbarium specimens—the main data source of this Factiva electronic database (Dow Jones & Company study—cannot provide the type of information nec­ 2008), at least 907 articles published in American and essary to support this assertion. Canadian newspapers (without counting newswires Ecologists and environmental managers only from press agencies) mentioned ‘purple loosestrife’ at began to consider purple loosestrife as a serious pest least once in their title or main text from 13 June after the publication of a special report on the species 1982 to 8 September 2008. The majority of these by the United States Fish and Wildlife Service articles only mention purple loosestrife as one (Thompson et al. 1987). This huge document written invasive species among others, but numerous papers, by three co-authors (including Ronald Stuckey) most published after 1988, contain substantial infor­ contains an exhaustive review of the biology, the mation on the plant. The portrayal of purple loose- ecology, the spread and the control methods of purple strife in these articles is rarely positive, as suggested loosestrife. A long list of the impacts of the species by the wide array of sobriquets used to describe the on wetland flora and fauna is also presented, but none species (Table 1). Purple loosestrife, ‘‘a plant with a are supported by field or experimental data; the take-no-prisoners approach’’ (Chicago Daily Herald, impacts are only suspected. Thompson et al. (1987) 15 Aug. 2004), is suspected of several ‘‘crimes acknowledged this lack of data, but nevertheless against the environment’’ (Worcester Telegram & added that ‘‘the replacement of a native wetland plant Gazette, 8 Sept. 1998), including ‘‘killing more than community by a monospecific stand of an exotic weed one million acres [400,000 ha] of wetlands across does not need a refined assessment to demonstrate North America each year’’ (Toronto Star, 4 Aug. that a local ecological disaster occurred’’ (p. 25). 1991) and ‘‘changing and hurting wetland environ­ The report by Thompson et al. (1987) has had (and ments more than human development’’ (Kitchener- still has) an enormous impact on wetland managers in Waterloo Record, 2 Sept. 1993). Once an invasion 123 1970 C. Lavoie

Table 1 Sobriquets used to Sobriquet Article(s) using Oldest article using Most recent article specifically depict purple the sobriquet (n) the sobriquet using the sobriquet loosestrife that have been found in Canadian and Invader 34 New York Times Detroit Free Press American newspapers published from 1982 to (17 Aug.1982) (3 Sept. 2008) 2008 and surveyed by the Menace 21 New York Times New York Times Factiva electronic database (30 Jan. 1983) (12 Aug. 2007) (907 articles) Pest 16 Toronto Star Anchorage Daily News (10 Aug. 1991) (28 Aug. 2008) Plague 16 Kitchener-Waterloo Record Boston Globe (13 Sept. 1991) (27 Apr. 2008) Killer 15 Toronto Star Hartford Courant (10 Aug. 1991) (3 July 2008) Scourge 15 New York Times Omaha World Herald (3 Sept. 1989) (30 Apr. 2007) Beauty 6 Globe and Mail Calgary Herald (23 July 1990) (29 June 2007) Peril 5 New York Times Worcester Telegram & Gazette (30 Jan. 1983) (8 Sept. 1998) Monster 4 National Post Chicago Sun—Times (17 Aug. 2000) (31 July 2005) Public enemy 4 Kitchener-Waterloo Record Reading Eagle number one (19 July 1991) (25 Aug. 2008) Death 3 Globe and Mail Hamilton Spectator (23 July 1990) (30 July 1994) Interloper 3 New York Times Colorado Springs Gazette (18 Aug. 1985) (19 July 2007) Thug 3 Chicago Daily Herald Philadelphia Inquirer (25 Apr. 2004) (15 Aug. 2008) Bane 2 Chicago Daily Herald Record (New Jersey) (24 June 2003) (1 Dec. 2007) Disaster 2 St. Louis Post—Dispatch Star Ledger (2 Jan. 1996) (8 Sept. 2004) Nightmare 2 Seattle Times Anchorage Daily News (27 Feb. 1990) (13 Oct. 2005) Offender 2 New York Times Anchorage Daily News (7 June 1992) (28 Aug. 2008) Outlaw 2 New York Times New York Times (26 Sept. 1993) (13 Nov. 1994) Rogue 2 Columbus Dispatch Colorado Springs Gazette (20 Apr. 2003) (19 July 2007) Strangler 2 New York Times New York Times (19 Nov. 1992) (15 May 2005) Terrorist 2 Plain Dealer Detroit News (14 June 2000) (7 Oct. 2004) Barbarian 1 Toronto Star Idem (30 July 1992)

123 Should we care about purple loosestrife? 1971

Table 1 continued Sobriquet Article(s) using Oldest article using Most recent article the sobriquet (n) the sobriquet using the sobriquet

Brute 1 Plain Dealer Idem (14 June 2000) Enemy of wildlife 1 Record (New Jersey) Idem (17 Aug. 2002) Evil incarnate 1 Washington Times Idem (19 Jan. 2000) Freddy Krueger of plants 1 National Post Idem (17 Aug. 2000) Icon of invasive exotics 1 Washington Post Idem (16 Apr. 2005) Natural tragedy 1 Star Ledger Idem (8 Sept. 2004) Pollution 1 Anchorage Daily News Idem (13 Oct. 2005) Rebellious child 1 Portland Press Herald Idem Press agency newswires were excluded from this (23 Apr. 2000) survey. Sobriquets are Time bomb 1 Toronto Star Idem presented by decreasing (9 Feb. 1991) order of mention occurs, purple loosestrife ‘‘is the only plant you can Ontario (Blossey 2002). The main objective of this see for miles’’ (Washington Post, 16 Apr. 2005); biological control program was to reduce the purple ‘‘instead [of having] 10,000 species at a site, you just loosestrife abundance to 10% of its current level over have one or two or three’’ (Chicago Daily Herald, 5 90% of its range (Malecki et al. 1993). The success of Oct. 2002). These are, of course, somewhat extreme this program has been reported regularly in newspa­ quotations, but I only found three papers presenting a pers: ‘‘At these sites, reduction of purple loosestrife different perspective on the species, i.e., questioning biomass and seed production of 60–90% are being whether the plant really had a negative impact on seen this season’’ (Kitchener-Waterloo Record, 14 wildlife (Cambridge Reporter, 30 Aug. 2001; Toronto Aug. 1997); ‘‘In some places where there used to be Star, 2 May 2002; Poughkeepsie Journal, 12 Oct. hundreds and hundreds of the plants, we have 10 or 2003). A detailed examination of the 907 articles 12 plants’’ (Winnipeg Free Press, 27 July 2001); published (Table 2; Appendix 1) revealed that the ‘‘The results were impressive. Within a month, the most frequent impact associated with purple loose- beetles had chewed the flowers off the plants, and the strife is, by far, crowding out the native plants, field had turned from purple to brown’’ (New Jersey followed by degrading waterfowl habitat and clog- Record, 17 Aug. 2002); ‘‘We have prairies where the ging drainage ditches. Twenty-five other impacts are purple loosestrife has been completely wiped out’’ mentioned in these articles, from potentially impor- (Chicago Daily Herald, 5 Oct. 2002); ‘‘Today, the tant (e.g., soaking up wetlands) to less serious (e.g., loosestrife is virtually gone from the original release ruining skating ponds). The majority of these impacts spot [of beetles]’’ (Republican, 12 June 2004); ‘‘the were negative. amount of loosestrife in the wetlands (…) declined From 1992, three European root-mining or leaf- 50% after 2002, the first year the beetles were eating beetle species were released in marshes released. Now, in some places, the plant is no longer invaded by purple loosestrife to control the abun- there’’ (Wausau Daily Herald, 26 July 2005); ‘‘this dance and the spread of the species. The insects were area once was covered with heavy infestations of first introduced in Maryland, Minnesota, New York, purple loosestrife but with the feeding done by the Pennsylvania, Virginia, and in the province of beetles released, it is hard to find a flowering purple 123 1972 C. Lavoie

Table 2 Positive (?), Impact(s) Article(s) mentioning negative (-) or null impacts the impact (n) associated with purple loosestrife mentioned in Crowds out the native plants or forms monocultures (-) 115 Canadian and American newspapers published from Degrades waterfowl habitats (-) 16 1982 to 2008 and that are Clogs drainage ditches, pipes or small ponds (-)1 5 surveyed by the Factiva Eliminates fish passages or spawning grounds (-) 7 electronic database (907 Soaks up wetlands (-) 6 articles) Plays a role in amphibian declines (-) 5 Helps bees to produce good honey (?) 4 Invades recreational areas and backyards (-) 3 Removes wetland’s ability to purify ground water and control 3 erosion and flooding (-) Cuts into revenues for communities that depend on tourism (-) 2 Extirpates rare plants (-) 2 Gobbles up all the nutrients in the soil (-) 2 Provides inspiration for wildlife photographers or artists (?) 2 Accelerates the evolution of marshes to less-productive swamps (-) 1 Acts as an alternate host for the cucumber mosaic virus (-) 1 Attracts butterflies (?) 1 Causes millions of dollars in agricultural damage in Nebraska (-) 1 Changes the chemical composition of water (-) 1 Creates a living Monet landscape (?) 1 Does not bother agriculture at low levels (null) 1 Does not invade people’s lawns (null) 1 Increases feeding by herbivores on other native plant species (-) 1 Prevents wind from mixing the water and oxygenating it (-) 1 Promotes the deposit of silt (-) 1 Press agency newswires Provides cover for predators (-) 1 were excluded from this Provides cover for spring-breeding ducks and shore birds (?) 1 survey. Impacts are Ruins ponds for skating in the winter (-) 1 presented by decreasing order of mention Threatens farmlands, pasturelands and crops (-) 1 loosestrife plant today’’ (Grand Rapids Press, 12 Sometimes it can take up to 7 years to see their effect Aug. 2007). Newspapers quoting biological control on the loosestrife’’ (Hartford Courant, 13 May 2007). specialists presented a somewhat different perspec­ tive on the phenomenon: ‘‘We’re not going to eradicate it. We’ll always have purple loosestrife. Discrepancies between scientists The best we can hope for is to try and keep it contained’’ (Toronto Star, 1 Aug. 1994); ‘‘The bugs The strong and rapid reaction of government agencies are not a panacea. (…) it may be a decade before we and wetland managers following the publication of see any real effect from control measures’’ (Kitch­ the Thompson et al. (1987) report ignited a debate a ener-Waterloo Record, 12 Aug. 1994); ‘‘Biocontrol is few years later about the real impact of purple long-term (…). It takes time’’ (Star Tribune, 24 June loosestrife on wildlife. This debate among ecologists 2001); ‘‘It takes a minimum of 3 years to begin seeing was essentially fuelled by the publication (from 1992 any kind of dieback, and it can take 10–20 years to to 2001) of five reviews and of a critical examination have a significant impact’’ (Boston Globe, 15 July of some papers on the species. Remarkably, the 2001); ‘‘The beetles don’t get the job done in 24 h. reviews—with one exception (Farnsworth and Ellis 123 Should we care about purple loosestrife? 1973

2001)—rely on a relatively high number of sources on North American wetlands. It is disturbing to find that have not been published in peer-reviewed the lack of quantitative data masked by the use of journals (personal communications or observations, biased language’’ (p. 229). The Anderson (1995) articles in popular magazines, reports, unpublished paper was rapidly followed by a critical analysis results, unpublished theses, workshop proceedings). (Hager and McCoy 1998) of two scientific reports Lack of peer review certainly does not mean that commonly used to support the hypothesis of a strong these references are not valuable, but they should impact of purple loosestrife on vegetation (Rawinski nevertheless be considered with great caution. In the and Malecki 1984; Thompson et al. 1987). Like first review (Mal et al. 1992), seven out of the 14 Anderson (1995), the authors concluded that these references used in the section describing the detri­ reports do not ‘‘clearly demonstrate that loosestrife mental impacts of purple loosestrife belong to this has the potential to cause serious ecological or category. Moreover, among the seven references economic damage’’ (p. 1075), essentially because of published in peer-reviewed journals, two were incor­ small sample sizes or lack of rigorous statistical rectly used. For instance, Fernald (1940, but origi­ analyses. nally published in 1938) never really reported the The reply to the Anderson (1995) and Hager and ‘‘loss of endemic flora of the St. Lawrence floodplain McCoy (1998) papers came from Bernd Blossey below Montreal following invasions by (…) L. (Cornell University). This ecologist is one of the salicaria’’ (Mal et al. 1992, p. 1309), because he leaders of the biological control program on purple never collected data to prove this assertion. Mal et al. loosestrife (Blossey 2002). He presented in a first (1992) also mentioned that Balogh and Bookhout paper a list of the ecosystem impacts of the plant (1989) reported in their paper that ‘‘dense stands of L. (Table 4 in Blossey 1999) containing 21 references, salicaria provided poor waterfowl and muskrat hab­ again with a substantial number (6) of unpublished itat and displaced more than 50% of the plant theses, proceedings or personal communications. biomass in some wetland communities in the USA’’ Several of the impacts mentioned are only suspected, (p. 1311), but Balogh and Bookhout (1989) were and seven references are cited not as support for simply referring to other sources, including the impacts, but as proof that purple loosestrife is Thompson et al. (1987) report. They never collected effectively used by animals. Blossey (1999) con­ data to support this hypothesis. Mal et al. (1992) cluded that ‘‘several of the predicted impacts [of concluded their review writing ‘‘In the above reports purple loosestrife on wetlands] have now been there is no proof of cause-and-effect although they confirmed’’ (p. 307). Two years later, he published certainly provide good circumstantial evidence that with two co-authors an additional review with an Lythrum invasion and spread is responsible for updated list of the ecosystem impacts of purple major changes in wetland plant communities’’ loosestrife (Table 1 in Blossey et al. 2001) using 16 (p. 1311). references. Only four of them were unpublished (at The second review was more critical about the that time), but there are some other problems with impact of purple loosestrife on ecosystems. Anderson this review. The Hickey and Malecki (1997) refer­ (1995) reviewed 71 papers involving the species, 34 ence used to support the hypothesis of a detrimental reporting original observations of animal interactions impact of purple loosestrife on black tern (Chlidonias or plant competition. However, 14 of the 34 papers niger (L.), Laridae) deals in fact with a native species were in fact popular magazine article (1), unpub­ of loosestrife (Decodon verticillatus (L.) Ell., Lythr­ lished reports (5), unpublished results or personal aceae). Whitt et al. (1999) effectively found a observations of the author (6) or unpublished theses negative impact of purple loosestrife on marsh wren (2), i.e., all sources very difficult to verify. Anderson (Cistothorus palustris (Wilson), Troglodytidae), but (1995) acknowledged that some evidence suggesting Blossey et al. (2001) neglected to mention the the presence (or the absence) of an impact of purple conclusion of their paper, i.e., ‘‘[the] avian use of loosestrife on wildlife were in fact anecdotes, but he loosestrife warrants further quantitative investigation concluded that ‘‘The results of this literature review because avian use may be higher than is commonly reveal an abundance of contradictory or ignored believed’’ (p. 113). Indeed, Whitt et al. (1999) did not evidence concerning the impact of purple loosestrife find any negative impact of purple loosestrife on the 123 1974 C. Lavoie

five other bird species that were observed in their are essentially correlative observational studies (field study. The studies cited as proof of an impact of surveys). Two studies used both methodologies: one purple loosestrife on plants or on wetland functions showed a reduction of the abundance and richness of are more convincing, but they are mainly presented as vascular plant seedlings in wetlands invaded by ‘field studies’ (suggesting correlative observational purple loosestrife (Yakimowski et al. 2005), while the studies in the field), though several of these works other concluded that the competitive effect of purple were in fact manipulative experiments in the field loosestrife on a rare species was not stronger than that (Table 3). Blossey et al. (2001) concluded that of other native plants (Denoth and Myers 2007). ‘‘although quantitative data on the ecosystem impacts How can we explain differences between manip­ of L. salicaria were scarce, recent evidence is ulative experiments and correlative observational growing and confirming large negative impacts of studies in the field? One could argue that uncon­ the species on native North American species and trolled field studies cannot detect the impact of purple ecosystem processes’’ (p. 1802). loosestrife because of confounding effects, while Farnsworth and Ellis (2001) wrote the only review observational study supporters would argue that on purple loosestrife based essentially on peer- manipulative experiments are over simplistic (Mor­ reviewed journals (11 out of 12 references) with rison 2002). Farnsworth and Ellis (2001) suspected details on the methods used and on the impacts (on that ‘‘part of this uncertainty is [probably] due to the plants) detected. They concluded that ‘‘despite two fact that different studies employ different, and decades of accounts, the actual dynamics of L. possibly incomparable, metrics to quantify the salicaria and its capacity to displace other wetlands impacts of L. salicaria on co-occuring plant species’’ species remain in doubt.’’ (p. 200). In summary, (p. 200). Schooler et al. (2006) suggested that ‘‘These although each review provided valuable information inconsistent results may be the result of (1) differ­ on purple loosestrife, most were somewhat biased, ences among studies in the spatial scale at which and relied on a substantial amount of information that plant diversity was measured, (2) differences in the was anecdotal or not screened by reviewers during a range of loosestrife abundance examined, and/or (3) formal evaluation process. Only one review was environmental differences due to different study really impartial, and this one painted an inconclusive locations’’ (p. 359). This last point is particularly picture of the species. interesting, since, as noted by Schooler et al. (2006), the only correlative observational studies that detected a negative impact of purple loosestrife on Purple loosestrife, science, and the press plant diversity (or on invertebrate diversity) were conducted in Western North America (Table 3). A large number of studies on the ecological impact of Keller (2000) hypothesized that the invasion of purple loosestrife on North American ecosystems purple loosestrife across North America ‘‘consists of were published in the 2000s, shedding new light on a first wave, in which the plant forms very dense the phenomenon. The main conclusions of these stands. Subsequently, these stands may decline, studies (and those published earlier) are presented in allowing reestablishment of the previous [plant] Table 3. My review was restricted to studies pub­ community’’ (p. 399). This could explain western lished in peer-reviewed journals to avoid possible study sites, which have generally been colonized by biases associated with other forms of communication. purple loosestrife within the last 30 years (S. S. The format of this review is similar to that of used by Schooler, personal communication, 22 June 2007), Farnsworth and Ellis (2001). are more strongly impacted than eastern sites (Mas­ A total of 34 studies were published on the impact sachusetts, New York, Ontario, Quebec) that have of purple loosestrife on plants (20), invertebrates (2), been invaded over a much longer period. For amphibians (2), birds (3) and ecological processes instance, despite the fact that massive purple loose- characterizing wetlands (7). Interestingly, most plant strife invasions have been reported along the St. studies showing at least some negative impacts are Lawrence River since the 1930s, and that this species mainly manipulative experiments (10 out of 11), was, at the beginning of the 2000s, by far the most while most papers (7) showing no negative impacts frequent exotic species in wetlands, there are now 123 Should we care about purple loosestrife? 1975 ) ) ) ) ) 2004 2003 ) ) 1999 1997 2004 2000 2004 ) ) ) ) ) ) ) 2006 2001 1999 1999 2007 1999 1997 ( ( Findlay ( Husband ( Vinebrooke ( ( ( ( ( ( Mahaney et al. Farnsworth and Ellis Hager ( Lavoie et al. ( Houlahan and Keller ( Treberg and Hager and Grabas and Laverty Mal et al. ( Grabas and Laverty Denoth and Myers Grabas and Laverty Weihe and Neely Reference(s) spp.) Typha , null, not clearly stated: ?) of purple loosestrife - 50% differed little from that [ , negative: ? loosestrife than in sites with a low density that of loosestrife cover. The competitive effect of loosestrife was not stronger than that of native plant species loosestrife, but the loosestrife density had no effect on seed production loosestrife than in uninvaded patches. Live or dead biomass did not differ between wetland patches with loosestrife and uninvaded patches was no correlation between richness and cover of loosestrife loosestrife any changes in density, richness or diversity of other plants. However, a lower biomass of other species was associated with an increasing biomass of loosestrife did other native species, but loosestrife was not better at early seedling growth in established vegetation than native species was similar of most other wetlands sampled Fewer seeds per ovule were produced in sites with a medium density of The growth of cattail was more affected by interspecific competition than Abundance did not decrease during a 20-year period of increasing loosestrife Over a 4-year period, loosestrife outcompeted cattail Seed production was not affected by loosestrife density Fewer fruits (up to 30%) were produced in sites with a high density of Species richness and diversity were greater in wetland patches with Richness did not differ between sites with or without loosestrife, and there Diversity of marshes dominated either by loosestrife or cattails ( Loosestrife was not more likely to dominate a wetland that native species without and with sites between differ not did biomass non-loosestrife or Total There was little correlation between the density or cover of loosestrife and Loosestrife was better able to suppress the growth of native seedlings than Diversity of wetlands with a loosestrife cover ­ ­ ­ or Null Null Null Null or Null or - - Null - Null Null or ? Null Null Null experiment experiment experiment manipulative experiment experiment experiment experiment ON—field survey NY—field survey CT—field survey MN—manipulative ON—manipulative MI—manipulative BC—field survey and ON—manipulative ON—manipulative ON—manipulative MN—field survey ON—field survey MA—field survey QC—field survey Sidalcea Scientific studies on the environmental impacts (as stated by the original authors themselves: positive: mallow hendersonii Vascular plants Boneset Eupatorium perfoliatum Broad-leaved cattail Typha latifolia Henderson’s checker- Narrow-leaved cattail Typha angustifolia Spotted Joe-Pye weed Eupatorium maculatum Spotted touch-me-not Impatiens capensis Wetland species Table 3 invasions in North American wetlands that have been published in peer-reviewed journals Species or ecologicalprocess(es) studied Study site(s) (state or province) and method(s) Impact Main conclusion(s) 123 1976 C. Lavoie ) ) ) ) ) ) ) ) ) 2001 2001 2001 2001 1996 2006 1994 ) 2005 2005 ) 1995 2002 ) ) ) , ) ), Brown 2005 2009 2005 1988 2006 2001 Wiedenmann ( ( ( ( ( ( et al. ( Gardner et al. ( Maerz et al. ( Brown et al. ( Maerz et al. ( Maddox and Gaudet & Keddy Gardner et al. ( Gardner et al. ( Gardner et al. ( Schooler et al. Yakimowski et al. Keddy et al. ( Weiher et al. ( Schooler et al. Brown and Mitchell Reference(s) Typha Typha ) stands. ) stands treatments spp.) stands compared Scirpus acutus Typha latifolia ) than in loosestrife stands ) than in loosestrife stands Typha Typha latifolia) Typha latifolia Typha latifolia spp.). However, the abundance and richness of Typha treatments ) treatments latifolia mesocosms) was lower than in cattail ( potential of cattail ( seedlings of vascular plant species were higher in wetlands not invaded by loosestrife than in invaded sites of the yield of neighbours (a set of 19 wetland species) species became dominated by loosestrife, and when this occurred, other dicots species were extirpated abundance of loosestrife increased. Plant diversity also decreased with an increasing abundance of loosestrife essentially because of lower pollinator visitation rates latifolia to loosestrife (1 nest) stands there was no relationship between loosestrife abundance and diversity of Lepidoptera Tadpole survival in loosestrife treatments was lower than in cattail ( Abundance was higher in cattail ( Tadpole survival in loosestrife treatments (laboratory experiments and There was no difference for tadpole survival between loosestrife and Nested almost exclusively (63 nests) in cattail ( There was no evidence for a negative effect of loosestrife on the recruitment Loosestrife was the most competitive plant amongst 44 species In a competition experiment, loosestrife caused an average reduction of 60% After 5 years, most microcosms inoculated with seeds from a pool of 24 Total species richness and the cover of native species decreased as the Seed production decreased (22–34%) in the presence of purple loosestrife, Abundance was higher in loosestrife than in bulrush ( Abundance was higher in loosestrife than in cattail ( Abundance was higher in cattail ( Species richness decreased with increasing abundance of loosestrife, but ­ ­ Null or - - Null ------? ? - Null or - experiment experiment experiment manipulative experiment experiment experiment experiment experiment NY—manipulative NY—manipulative NY—manipulative IL—field survey MN, ON—field survey, QC—manipulative ON—manipulative ON—manipulative ID, OR, WA—field survey OH—manipulative WA—field survey WA—field survey WA—field survey ID, OR—field survey WA—field survey Lythrum Quiscalus Bufo Hyla continued americanus quiscula versicolor alatum Amphibians American toad Gray treefrog Birds Common grackle Invertebrates Amphipod species Copepod species Diptera species Lepidoptera species Ostracod species Winged loosestrife process(es) studied province) and method(s) Species or ecological Study site(s) (state or Impact Main conclusion(s) Table 3 123 Should we care about purple loosestrife? 1977 ) ) ) ) ) ) ) ) 1997 1999 1999 1999 1999 1999 1999 1984 ) ) ) ) ) ) ) rlocher and 1996 1996 2007 2006 2003 2005 2005 ¨ Biddiscombe ( ( ( ( ( Wiedenmann ( Wiedenmann ( Malecki ( Ba Emery and Perry Grout et al. ( Welsch and Yavitt Fickbohm and Zhu Welsch and Yavitt Whitt et al. ( Whitt et al. ( Maddox and Whitt et al. ( Maddox and Whitt et al. ( Whitt et al. ( Whitt et al. ( Rawinski and Reference(s) ) spp.; 37 Phalaris spp.) shoots, ) than for Typha glauca Typha Typha Typha latifolia spp.) stands ) shoots decomposed in a similar a in decomposed shoots ) Typha spp.) or reed canarygrass ( Typha Typha latifolia Typha ) ) Typha latifolia ) stands Carex lyngbyei types stands. None was found in loosestrife stands types nests) stands. Females nested later in loosestrife stands, but nesting success was not significantly altered types types fashion covered by loosestrife, cattail ( ( loosestrife. From the end of September to mid-December, leaf detachment in loosestrife followed an exponential decay curve, while cattail did not lose any leaves in the same period arundinacea but cattail shoots decomposed more rapidly than loosestrife stems ( Abundance did not differ between loosestrife stands and the other vegetation All nests found during the survey (35) were located in cattail ( Abundance was lower in loosestrife stands than in other vegetation types Nested exclusively (11 nests) in cattail ( Abundance did not differ between loosestrife stands and the other vegetation Nested extensively in both loosestrife (30 nests) and cattail ( Abundance did not differ between loosestrife stands and the other vegetation Abundance was higher in loosestrife stands than in other vegetation types Abundance did not differ between loosestrife stands and the other vegetation ( cattail and stems Loosestrife Senescence of leaves started earlier for cattail ( There was no difference in mean rates of net nitrification amongst soils Nitrogen mineralization rates were higher in loosestrife stands than in cattail Loosestrife leaves decomposed more rapidly than cattail ( Loosestrife decay rate was four times higher than that of Lyngbyei’s sedge ? ? Null - Null - - - Null Null Null ? Null Null ? experiment experiment manipulative experiment experiment experiment MN—manipulative BC—manipulative NY—field survey and NY—field survey MI—field survey NY—field survey MI—field survey IL—field survey MI—field survey IL—field survey MI—field survey MI—field survey MI—field survey NY—manipulative NB—manipulative Melospiza Dendroica Cistothorus Cistothorus continued Geothlypis trichas palustris Agelaius pheoniceus platensis georgiana petechia tissues tissues (continued) Nitrogen cycling Common Yellowthroat Marsh wren Red-winged blackbird Sedge wren Swamp sparrow Yellow warbler Processes Decomposition of plant Decomposition of plant process(es) studied province) and method(s) Table 3 Species or ecological Study site(s) (state or Impact Main conclusion(s) 123 1978 C. Lavoie Ontario, ON ) ) ) ) 1996 1998 2006 2007 Ohio, ( ( ( ( Emery and Perry Templer et al. Fickbohm and Zhu Welsch and Yavitt Reference(s) OH )or )or spp.) New York, NY Typha Fig. 2 A floodplain of the St. Lawrence River (near Montreal) invaded by purple loosestrife in 2000. Although such invasions are spectacular, the phenomenon is infrequent today in wetlands bordering the river (photograph: M. Jean, Environ­ Typha angustifolia ment Canada) New Brunswick, relatively few sites (only 9% of all sampling stations NB ). Loosestrife had a greater phosphorus

) stands than in cattail ( with purple loosestrife) where the species dominates the plant cover (Lavoie et al. 2003). Massive infestations are still found (Fig. 2), but the large-

Minnesota, scale invasions similar to that of observed at the spp.) shoots. Loosestrife stems had more rapid aerial

MN Commune de la Baie du Febvre in the 1940s and 1950s (Fig. 1) are no longer present. For the moment, ) Phragmites australis Typha

Phalaris arundinacea there is no known mechanism that could be proposed

Michigan, to support this hypothesis (changing nutrient dynam­

MI ics? long-term effect of a pathogen?), but it is certainly worth examining, considering that similar Typha latifolia stands that of cattail ( leaching of phosphorus overwinter than did cattail shoots loosestrife than in those associated with cattail ( common reed ( stock than cattail, and a higher rate of phosphorus turnover than cattail and common reed ( canarygrass ( phenomena have also been observed for other Initial phosphorus concentration of senescent loosestrife leaves was twice Porewater phosphate was significantly lower in sediments associated with Loosestrife plants transpired about twice the amount of water as cattail There was a greater soil organic accumulation in loosestrife and reed invasive species (Simberloff and Gibbons 2004). Four other papers could have been added to Table 3, Massachusetts, but they are somewhat different than the others since MA ­ ­ ­ they report conclusions on purple loosestrife control experiments. In an herbicide experiment, Gabor et al.

Illinois, (1995, 1996) concluded that grass and sedge stems

IL were more numerous in treatment plots than in control plots. Morrison (2002) compared the vegetation of

Idaho, sites without treatments with others where purple

ID loosestrife was removed by hand. Species richness, diversity and total percent cover were similar across all experiment experiment outdoor experiment treatments. In a biological control experiment, Landis MN—manipulative NY—field survey NY—manipulative NY—field survey and ? Washington et al. (2003) found that the richness of vascular plants Connecticut, WA generally increased as purple loosestrife cover and CT height declined because of the defoliating action of beetles. Quebec, Studies on animals were essentially observational QC studies (five out of seven), but were just as divided in continued terms of results. Fourteen species or groups of species Oregon, British Columbia, were studied: six were negatively affected by purple concentration accumulation BC OR Table 3 Species or ecologicalprocess(es) studied Phosphate or phosphorus Study site(s) (state or province) and method(s) Impact Main conclusion(s) Plant transpiration Soil organic matter loosestrife, while the others were either undisturbed 123 Should we care about purple loosestrife? 1979 or positively affected by invasions. The stronger In summary, the image of purple loosestrife negative impacts detected were on tadpoles and on depicted by scientific studies (lacking definition) is marsh wren (Cistothorus palustris), a species ironi­ far removed from that portrayed by newspapers cally benefiting for nesting from the presence of (alarming). Purple loosestrife is certainly an invader common reed (Phragmites australis (Cav.) Trin. ex (sensu Vale´ry et al. 2008), and some native species Steud., Poaceae), another highly invasive marsh plant likely suffer from an invasion, but stating that this in Eastern North America (Benoit and Askins 1999). plant has ‘large negative impacts’ on wetlands is No studies have been published on fish, mammals or probably exaggerated. The most commonly men­ waterfowl. tioned impact (purple loosestrife crowds out native There are few doubts that American toad (Bufo plants and forms a monoculture) is controversial and americanus Holbrook, Bufonidae) tadpoles are has not been observed in nature (with maybe one affected by compounds leached from purple loose- exception). There is certainly no evidence that purple strife leaves, but it should be noted that phenolic loosestrife ‘kills wetlands’ or ‘creates biological concentrations used in experimental studies deserts’, as it is repeatedly reported. For instance, (15 mg l -1) were much higher than those measured 63 insect genera, representing 38 families and seven in the field (1–11 mg l- 1; Maerz et al. 2005). For orders, have been collected from purple loosestrife birds, Maddox and Wiedenmann (2005) criticized invaded sites in Manitoba (Diehl et al. 1997). There avian studies based on the occurrence of birds rather are no published studies (at least in peer-reviewed than their nesting success, since occurrence data journals) demonstrating that purple loosestrife has an alone can be a very poor predictor of habitat quality. impact on waterfowl or fishes. All the other negative Unfortunately, only three bird species have been impacts associated with purple loosestrife in the press studied for nesting, i.e., common grackle (Quiscalus have not been the object of a study (and many have quiscula (L.), Icteridae; negative impact), marsh wren never even been considered by scientists), except for (negative impact) and red-winged blackbird (Agela­ a possible impact on amphibians that has been tested ius phoeniceus (L.), Icteridae; no impact). (to date) only on two species, one reacting negatively. Considering all the suspected impacts of purple Some impacts (e.g., clogging drainage ditches) are of loosestrife on wetlands, there are relatively few little interest to ecologists, but others (e.g., altering studies on the relationships existing between this wetland hydrology) should have been studied more plant and the ecological processes characterizing extensively considering the apparent public consen­ marshes. There are some differences between purple sus on the detrimental effects of purple loosestrife on loosestrife and cattails (Typha spp.) in the decompo­ wildlife. sition of plant tissues, nitrogen cycling and soil How can we explain such differences between organic matter accumulation, but the real impact of scientific reports and press articles? It is of course such differences on wetlands is difficult to assess or much harder to publish a newspaper article stating only conjecture. For instance, Emery and Perry there is no problem with an invasive species than one (1996) suggest that a wetland invaded by purple highlighting the possible negative consequences of loosestrife may function less effectively as a nutrient this species. A wetland invaded by purple loosestrife biofilter, because the plant would provide more is much more spectacular (and potentially of interest phosphorus to the ecosystem, and Fickbohm and for readers) than a marsh invaded by a less showy Zhu (2006) suggest that higher soil nitrogen miner­ species like reed canarygrass. Biological control alization rates found in purple loosestrife stands could specialists have also done an excellent job with the represent a mechanism by an exotic plant to mediate press to sensitize the public to the problems associ­ favourable environmental conditions for its own ated with purple loosestrife and to the potential of advantage; in both cases, these hypotheses have control experiments; this work is relevant and never really been tested. Purple loosestrife plants important in a context of growing concern about apparently transpire about twice the amount of water invasive species. Of the 185 interviews given to as cattails (Fickbohm and Zhu 2006), but there is no newspapers by purple loosestrife specialists from field study demonstrating an impact on the hydrology 1982 to 2008 (Appendix 2), 44 (24%) were given by of a marsh. scientists that had published at least one peer-review 123 1980 C. Lavoie paper on purple loosestrife, as revealed by the Web of associated with purple loosestrife, but at the same Science© database (Thomson Reuters 2008). Thirty- time, it also agreed to construct a waste water eight of the 44 interviews (86%) were given by treatment system near the marsh using the highly ecologists or entomologists that had conducted at invasive haplotype M of common reed as a biological least one study on the biological control of the plant. agent (C. Lavoie, personal observation). This is The opinion of biological control specialists is paradoxical, since contrary to purple loosestrife, extremely important, but ecologists who have con­ there are several scientific papers suggesting that ducted studies finding no impact of purple loosestrife common reed has a strong impact on the hydrology on wildlife should be encouraged to communicate and plant diversity of marshes (Windham and their results with the public. In other words, a more Lathrop 1999; Keller 2000; Hanson et al. 2002; balanced view on the purple loosestrife phenomenon Osgood et al. 2003; Lavoie et al. 2003; Silliman and would certainly be welcome. Bertness 2004). Another aspect that could explain differences Secondly, using beetles to control purple loose- between science and the press is the misuse of the strife is certainly far better (and probably more Thompson et al. (1987) report. This document— effective in the long term) than using herbicides, but excellent in many respects—should not be used to this solution remains quite expensive, especially for support strong negative impacts of purple loosestrife local non-profit organizations usually operating with on wetlands, but instead as a pioneer work highlight­ small budgets. Each beetle individual may cost up to ing the possible consequences of a plant invasion. 50 cents (Blossey, interviewed by the Wall Street One example of this misuse: at least 16 newspaper Journal, 9 Sept. 2006), and thousands have to be articles mentioned that a single purple loosestrife released at a particular site to have an impact on the individual may produce up to 2,7 million seeds per plant. There is no precise evaluation of the total year, not including the articles simply mentioning number of beetles that have been released for control, ‘millions’. This data is frequently used by wetland but available numbers (Minnesota: 7 million from managers (and consequently reported by the press) as 1992 to 2003; New Jersey: 1.6 million from 1997 to an argument in favour of a rapid intervention against 2006; Ontario: 320,000 before 1998; Dech and Nosko the species. How many people know, however, that 2002; Lindgren 2003; Scudder et al. 2006) suggest this number was estimated from only three individual that a considerable amount of money has been plants? (Thompson et al. 1987, p. 7). allocated to this program. Several biological control trials obtained spectacular results (e.g., total eradica­ tion of purple loosestrife only three to 6 years after Should we care about purple loosestrife? the introduction of beetles; Landis et al. 2003, Lindgren 2003), but some others failed (e.g., Dech Even if the impacts of purple loosestrife on wildlife and Nosko 2002; Denoth and Myers 2005 in intertidal are smaller than suspected, one could argue that areas). Carson et al. (2008) estimated that ‘‘The controlling the spread of the plant is worthwhile, amount of damage caused [by introduced leaf- considering that wetlands are threatened in North feeding beetles] would rarely have been sufficient to America and do not need additional pressures to allow the formerly dominant native cattails (…) to re­ potentially disturb their functions. This position is establish in [purple loosestrife] invaded wetlands [of reasonable; nevertheless it is not without conse­ New York and Pennsylvania]’’ (p. 80). The only quences. Firstly, focusing on purple loosestrife long-term (10 years) assessment of biological control instead of on other invasive species or on wetland efforts (Grevstad 2006) concluded, for central New losses to agriculture or urban sprawl could divert the York State, that biological control had ‘‘significant attention of environmental managers from more impacts at the level of individual plants [and on urgent protection needs. For instance, the Board of flowering] but not at the population level. Plants Directors of the Marais-du-Nord Natural Reserve, were found to be shorter on average (…) [but] no which protects a marsh and a lake providing water to change was found in overall plant density or in the 250,000 residents of Quebec City (Canada), agreed to size of the purple loosestrife stands’’ (p. 6). ‘‘Surveys distribute brochures to visitors on the dangers [of the beetles] away from release sites revealed 123 Should we care about purple loosestrife? 1981 limited spread of beetles to new areas. Site occupa­ the ‘disaster’ of hawkweed and purple loosestrife, I tion rates were surprisingly low given the amount of choose the flowers every time’’ (6 Mar. 2006). The time passed and the proximity of sampled sites to bill was not passed, but a representative of the Alaska successful releases’’ (p. 7). Moreover, at several sites, Legislature recently introduced (2008) a similar other invasive species like common reed or reed legislation (HB 330). It should be noted, however, canarygrass increased due to the control of purple that the penalties (fine, jail) associated with the HB loosestrife (Blossey et al. 2001), hardly a gain from 324 bill and mentioned in the Anchorage Daily News the biodiversity point of view. In summary, the purple (3 Feb. 2006) were probably, in fact, highly exag­ loosestrife biological control experiment was cer­ gerated (S. Hancock and J. Ostnes, personal commu­ tainly worth testing, especially because it was nications, 9 and 10 September 2008). extremely well conducted, but a detailed cost/benefit analysis would be welcome to support further devel­ opments. The costs and the benefits of other control Conclusion measures (chemical) should also be evaluated and compared to those of biological control, to put things The ‘Precautionary Principle’ has been invoked at in perspective. To my knowledge, the only recent least twice (Blossey et al. 2001; Lee 2002) to support economical analysis on purple loosestrife is that of rapid action against purple loosestrife. For instance, Barbier and Knowler (2006), who estimated damages Blossey et al. (2001)‘‘consider particularly danger­ associated to individuals escaping from nurseries to ous to assume that there are no impacts [associated US$ 28 million per year. However, their analysis was with purple loosestrife] based on absence of inves­ apparently based on a previous estimation of the tigations or published data. (…) Lack of scientific damages calculated by Thompson et al. (1987), certainty should not be a reason to postpone damages that were only conjecture. measures to prevent degradation’’ (p. 1795–1796). Finally, the fear of purple loosestrife largely Once again, this is a reasonable position that I amplified by the press may lead to disproportionate personally support, but it is much more valuable for actions considering the real impact this plant has on newcomers than for invaders coexisting with native ecosystems. In this respect, the recent discovery of species for more than a century. I underline again that purple loosestrife in Alaska is particularly enlighten­ purple loosestrife has been naturalized in southern ing. The plant was found growing in a wetland near Quebec since at least 1865, and massive infestations Anchorage in fall 2005. The classic speech on the were reported along the St. Lawrence River more species rapidly appeared in the local newspaper than 70 years ago, a situation well known and (Anchorage Daily News): ‘‘This is a really horrific described in the Thompson et al. (1987) report (see invader (…). This plant (…) [will] cover the marsh p. 32–33). If purple loosestrife really affects wildlife (…). There would be no more geese, no ducks, no so strongly, the consequences of the presence of the terns, no swans (…). It drives out native plants such species should have been dramatic after a so long as cattails, overgrows wetlands, ruins fish passage, period in the 34,800 ha of wetlands still remaining even blocks access from the bank for recreation. (…) along the river. Such consequences should have been the ecosystem as we know it will not function any very easy to demonstrate. Unfortunately, nobody took more’’ (13 Oct. 2005). Officials rapidly launched an time to investigate those wetlands before initiating a awareness campaign about purple loosestrife, and coast-to-coast campaign against purple loosestrife. herbicide spraying was proposed as an eradication Studies on St. Lawrence River wetlands may have measure. In 2006, in response to activists opposed to delayed control programs by some years, but where the spraying of herbicides on purple loosestrife or was the emergency considering that the plant had other weeds, the Alaska Legislature proposed a bill already been present in North America for 150 years? (HB 324) to charge anyone possessing purple loose- Such studies would have probably indicated that the strife seeds or potted plants with as much as a $ 10 situation was much less problematic than suspected 000 fine and a year in jail (3 Feb. 2006). An artist (see Lavoie et al. 2003), and perhaps wetland replied in the newspaper: ‘‘When I compare the managers would have been more cautious before undeniable disaster of herbicide contamination with taking large-scale control actions. 123 1982 C. Lavoie

Biologists should be extremely cautious before indicator of anthropogenic disturbances, the resources extending these conclusions on the purple loosestrife and efforts devoted to removing this species might be invasion phenomenon to other invasive plant species. better focused on more effective means to protect Detailed meta-analyses on other invaders are first wetlands against disturbances. Raising this issue can required to decipher whether the purple loosestrife only help biological invasion specialists do better invasion is a particular case or a much more science. widespread phenomenon than expected. Above all, this critical examination of the purple loosestrife Acknowledgments This work was financially supported by history in North America should absolutely not be the Natural Science and Engineering Research Council of Canada. I thank Jacques Brisson and Jacques Brodeur considered as a case against biological control. (Universite´ de Montre´al), Conrad Cloutier (Universite´ Laval) Biological control is probably the only long-term and Sylvie de Blois (McGill University), all invasive plant or viable solution to reduce the impact of invasive plants biological control specialists, Jean Hamann (Universite´ Laval), already well established. On the other hand, there are science journalist, and two anonymous reviewers for heated debates and numerous comments on earlier drafts of this paper. at least three studies (Rachich and Reader 1999; Farnsworth and Ellis 2001; Hager 2004) suggesting that purple loosestrife invasions are disturbance- Appendix 1 dependent. Therefore, as suggested by Gurevitch and Padilla (2004), if purple loosestrife is not a See Table 4 primary cause of extinction or a major contributor to the decline of other species, but is instead an

Table 4 Positive (?), negative (-) or null impacts associated with purple loosestrife mentioned in Canadian and American newspapers published from 1982 to 2008 and that are surveyed by the Factiva electronic database (with references) Impact(s) Article(s) mentioning Reference(s) the impact (n)

Crowds out the native plants or 115 Anchorage Daily News forms monocultures (-) (13 Oct. 2005, 28 Aug. 2008) Atlanta Journal—Constitution (14 Sept. 2000) Baltimore Sun (10 Aug. 2006) Blade (4 Jan. 2006) Boston Globe (28 July 2002, 12 July 2007, 22 July 2007, 27 Apr. 2008, 4 Aug. 2008) Buffalo News (15 July 2000, 8 June 2003) Burlington Free Press (4 Dec. 2006) Calgary Herald (19 Sept. 2006) Centre Daily Times (2 July 2008) Chicago Daily Herald (22 Sept. 2002, 5 Oct. 2002, 24 June 2003, 15 Aug. 2004)

123 Should we care about purple loosestrife? 1983

Table 4 continued Impact(s) Article(s) mentioning Reference(s) the impact (n)

Chicago Sun—Times (1 Aug. 2000, 12 Aug. 2001, 31 July 2005) Chicago Tribune (17 May 2004, 5 Nov. 2004) Connecticut Post (29 May 2007, 2 June 2007) Detroit Free Press (3 Sept. 2008) Detroit News (7 Oct. 2004, 11 Aug. 2007) Evansville Courier (19 Mar. 2000, 11 Jan. 2004) Globe and Mail (23 July 1990, 22 Aug. 1991, 23 July 1992, 12 Mar. 1993, 17 Aug. 2002) Grand Rapids Press (28 July 2000, 7 Feb. 2002, 18 Aug. 2002, 3 May 2005) Hamilton Spectator (24 July 1992, 28 Jan. 1993, 13 Aug. 1994) Hartford Courant (13 May 2007) Kitchener-Waterloo Record (13 Aug. 1993, 2 Sept. 1993, 1 Aug. 1995, 26 July 1996, 14 Aug. 1997) Lancaster New Era (9 Aug. 2007) Milwaukee Journal Sentinel (5 Aug. 2002) National Post (17 Aug. 2000) New Haven Register (22 Feb. 2007) New York Daily News (21 Aug. 2002) New York Times (13 June 1982, 18 Aug. 1985, 9 June 1996, 8 July 1997, 23 June 2002) Omaha World Herald (15 July 2001, 21 June 2002) Oregonian (9 Oct. 2000) Pantagraph Bloomington (11 Apr. 2003) Patriot Ledger (22 Apr. 2000, 6 Aug. 2004) 123 1984 C. Lavoie

Table 4 continued Impact(s) Article(s) mentioning Reference(s) the impact (n)

Patriot News (19 June 2000, 11 July 2002) Peoria Journal Star (8 July 2007) Pittsburgh Post—Gazette (28 Feb. 2000, 19 June 2000) Plain Dealer (14 Apr. 2005) Portland Press Herald (27 Sept. 2001, 21 June 2002, 24 July 2008) Poughkeepsie Journal (12 Oct. 2003) Providence Journal (20 July 2006, 2 Aug. 2006) Record (New Jersey) (26 Aug. 2001) Republican (12 June 2004) Rocky Mountain News (30 July 2000, 3 Sept. 2000) Seattle Times (6 Aug. 2004, 17 Aug. 2006) South Bend Tribune (14 June 2004, 2 July 2006, 18 July 2007) St. Louis Post—Dispatch (6 July 1989, 24 Dec. 1991, 5 Feb. 1992, 24 July 1996, 15 Oct. 2001, 15 June 2002) Star Ledger (4 Aug. 2001, 8 Sept. 2004) Star Tribune (28 Mar. 1994, 24 June 2001) Times Union (31 Aug. 2006) Toronto Star (9 Feb. 1991, 24 Feb. 1991, 4 Aug. 1991, 25 Apr. 1992, 26 July 1992, 5 Aug. 1995, 14 Sept. 1995, 16 Aug. 1997) Wall Street Journal (9 Sept. 2006) Washington Post (2 Sept. 2000, 26 Oct. 2002, 16 Dec. 2006) Wichita Eagle (25 Jan. 2002) Winnipeg Free Press (23 July 2003, 15 Aug. 2005)

123 Should we care about purple loosestrife? 1985

Table 4 continued Impact(s) Article(s) mentioning Reference(s) the impact (n)

Worcester Telegram & Gazette (8 Sept. 1998, 13 Aug. 2004) York Daily Record (26 Oct. 2005) Degrades waterfowl habitats (-) 16 Anchorage Daily News (13 Oct. 2005, 28 Aug. 2008) Calgary Herald (19 Sept. 2006) Daily Camera (20 Nov. 2007) Detroit News (7 Oct. 2004) Hamilton Spectator (24 July 1992) Kitchener-Waterloo Record (26 July 1996, 14 Aug. 1997) Patriot News (19 June 2000) Pittsburgh Post Gazette (19 June 2000) Seattle Times (11 Oct. 1998) Star Ledger (8 Sept. 2004) Toronto Star (9 Feb. 1991, 14 Sept. 1995) Washington Post (2 Sept. 2000) Worcester Telegram & Gazette (8 Sept. 1998) Clogs drainage ditches, pipes or 15 Anchorage Daily News small ponds (-) (13 Oct. 2005) Boston Globe (27 Apr. 2008) Burlington Free Press (4 Dec. 2006) Chicago Daily Herald (15 Aug. 2004) Columbian (28 Aug. 2008) Hartford Courant (3 July 2008)

123 1986 C. Lavoie

Table 4 continued Impact(s) Article(s) mentioning Reference(s) the impact (n)

Kitchener-Waterloo Record (2 Sept.1993) New York Daily News (21 Aug. 2002) Omaha World Herald (15 July 2001) Patriot News (19 June 2000) Rocky Mountain News (3 Sept. 2000) Seattle Times (27 Feb. 1990, 11 Oct. 1998) Star Tribune (28 Mar. 1994) Wausau Daily Herald (26 July 2005) Eliminates fish passages or 7 Anchorage Daily News spawning grounds (-) (13 Oct. 2005) Detroit News (7 Oct. 2004) Globe and Mail (23 July 1990) Milwaukee Journal Sentinel (5 Aug. 2002) New York Daily News (21 Aug. 2002) Republican (12 June 2004) Worcester Telegram & Gazette (8 Sept. 1998) Soaks up wetlands (-) 6 Globe and Mail (12 Mar. 1993) Kitchener-Waterloo Record (2 Sept. 1993) Record (New Jersey) (17 Aug. 2002, 13 Dec. 2005) Toronto Star (1 Aug. 1994, 16 Aug. 1997) Plays a role in amphibian declines 5 Daily Camera (-) (20 Nov. 2007) Detroit News (7 Oct. 2004)

123 Should we care about purple loosestrife? 1987

Table 4 continued Impact(s) Article(s) mentioning Reference(s) the impact (n)

Republican (12 June 2004) Seattle Post Intelligencer (10 Mar. 2004) South Bend Tribune (14 June 2004) Helps bees to produce good honey 4 Boston Globe (?) (27 Apr. 2008) Hamilton Spectator (13 Aug. 1994) Toronto Star (30 July 1992) Worcester Telegram & Gazette (13 Aug. 2004) Invades recreational areas and 3 Anchorage Daily News backyards (-) (13 Oct. 2005) Boston Globe (27 Apr. 2008) Worcester Telegram & Gazette (8 Sept. 1998) Removes wetland’s ability to 3 Green Bay Press Gazette purify ground water and control (31 July 2004) erosion and flooding (-) Toronto Star (4 Aug. 1991) Wall Street Journal (14 Jan. 1998) Cuts into revenues for 2 Rocky Mountain News communities that depend on (30 July 2000, 3 Sept. 2000) tourism (-) Extirpates rare plants (-) 2 Star Ledger (4 Aug. 2001) Wausau Daily Herald (26 July 2005) Gobbles up all the nutrients in the 2 Toronto Star soil (-) (23 July 1992, 30 July 1992) Provides inspiration for wildlife 2 Chicago Daily Herald photographers or artists (?) (5 Oct. 2002) Star Ledger (8 Sept. 2004) Accelerates the evolution of 1 Globe and Mail marshes to less-productive (23 July 1992) swamps (-) Acts as an alternate host for the 1 Omaha World Herald cucumber mosaic virus (-) (21 June 2002)

123 1988 C. Lavoie

Table 4 continued Impact(s) Article(s) mentioning Reference(s) the impact (n)

Attracts butterflies (?) 1 Record (New Jersey) (26 Aug. 2001) Causes millions of dollars in 1 Wichita Eagle agricultural damage in Nebraska (21 Jan. 2002) (-) Changes the chemical composition 1 Boston Globe of water (-) (27 Apr. 2008) Creates a living Monet landscape 1 Republican (?) (12 June 2004) Does not bother agriculture at low 1 Wall Street Journal levels (null) (14 Jan. 1998) Does not invade people’s lawns 1 Wall Street Journal (null) (14 Jan. 1998) Increases feeding by herbivores on 1 Globe and Mail other native plant species (-) (22 Aug. 1991) Prevents wind from mixing the 1 Toronto Star water and oxygenating it (-) (9 Feb. 1991) Promotes the deposit of silt (-) 1 Pittsburgh Post—Gazette (19 June 2000) Provides cover for predators (-) 1 Toronto Star (9 Feb. 1991) Provides cover for spring-breeding 1 New York Times ducks and shore birds (?) (13 June 1982) Ruins ponds for skating in the 1 Boston Globe winter (-) (27 Apr. 2008) Threats farmlands, pasturelands 1 Hartford Courant and crops (-) (3 July 2008) Press agency newswires were excluded from this survey. Impacts are presented by decreasing order of mention

Appendix 2

See Table 5

Table 5 Specialists interviewed in articles on purple loosestrife published from 1982 to 2008 in Canadian and American newspapers that are surveyed by the Factiva electronic database (907 articles) Specialist interviewed Reference(s)

Adams, Mark (biologist) Globe and Mail (affiliation not specified) (23 July 1992) Amom, Jim (biologist) Dayton Daily News Wright State University (Ohio) (18 Sept. 2000) Anderson, Joe (project manager) Portland Press Herald York County Soil and Water Conservation District (Maine) (24 July 2008)

123 Should we care about purple loosestrife? 1989

Table 5 continued Specialist interviewed Reference(s)

Armson, Erling (biologist) Cambridge Reporter (affiliation not specified) (30 Aug. 2001) Ball, Garth (wetland specialist) Winnipeg Free Press Manitoba Conservation (23 July 2003) Barker, Simon (horticulturist) St. Louis Post—Dispatch Bowood Farms (Missouri) (15 June 2002) Block, Steven (biologist) Boston Globe Massachusetts Wetlands Restoration Program (15 July 2001) Blossey, Bernd (biologist and professor) New York Times Department of Natural Resources, Cornell University (New York) (8 July 1997) Seattle Post Intelligencer (10 Mar. 2004) Toronto Star (16 Aug. 1997) Wall Street Journal (14 Jan. 1998, 9 Sept. 2006) Boettner, Cynthia (extension educator) Patriot Ledger Department of Plant and Soil Sciences, University of Massachusetts (12 June 2004) Republican (12 June 2004) Bowen, Brian (administrator) Wall Street Journal Tennessee Division of Natural Heritage (14 Jan. 1998) Bowles, Greville (entomologist and research technician) Hamilton Spectator Biocontrol Laboratory, University of Guelph (Ontario) (30 July 1994) Toronto Star (14 Sept. 1995) Brickman, Gerald (owner) Kitchener-Waterloo Record Brickman’s Country Flowers and Botanical Gardens (Ontario) (13 Sept. 1991) Bright, Chris (researcher) Seattle Times (affiliation not specified) (11 Oct. 1998) Brunk, Joe (weed director) Wichita Eagle Sedgwick County (Kansas) (21 Jan. 2002) Burke, Steven (weed control program manager) Seattle Times King County (Washington) (6 Aug. 2004) Campbell, Hugh (beekeeper) Hamilton Spectator (affiliation not specified) (13 Aug. 1994) Carroll, Dan (biologist) Buffalo News New York Department of Environmental Conservation (15 July 2000) Toronto Star (30 Nov. 1994) Casagrande, Richard (entomologist) Providence Journal College of the Environment and Life Sciences, University of Rhode Island (10 Sept. 1995) Chianese, Bob (director) Star Ledger Phillip Alampi Beneficial Insect Rearing Laboratory (New Jersey) (4 Aug. 2001)

123 1990 C. Lavoie

Table 5 continued Specialist interviewed Reference(s)

Ciciersci, Lauralou (national media co-ordinator) Cambridge Reporter Ducks Unlimited Canada (30 Aug. 2001) Clay, Bob (biologist) Globe and Mail Ducks Unlimited Canada (12 Mar. 1993) Connors, Kevin (title not specified) Patriot News United States Department of Agriculture (19 June 2000) Cook, Carol (administrator) South Bend Tribune Save the Dunes Council (Indiana) (14 June 2004) Corrigan, Jim (director and research associate) Globe and Mail Ontario Biological Control Program and University of Guelph (Ontario) (3 Aug. 1994) Hamilton Spectator (4 Aug. 1995) Kitchener-Waterloo Record (12 Aug. 1994, 1 Aug. 1995, 14 Aug. 1997) Toronto Star (5 Aug. 1995, 16 Aug. 1997) Cortilet, Tony (biocontrol specialist) Star Tribune Minnesota Department of Agriculture (24 June 2001) Coulson, Daryl (biologist) Kitchener-Waterloo Record Ministry of Natural Resources of Ontario (2 Aug. 1991) Cunningham, Sally (master gardener) Buffalo News Cornell Cooperative Extension of Erie County (New York) (8 June 2003) Davies, Barry (title not specified) Toronto Star Ontario Bee Keepers Association (30 July 1992) De Clerck-Floate, Rosemarie (scientist) Globe and Mail Agriculture Canada (3 Aug. 1994) Dibble, Alison (ecologist) Portland Press Herald Maine Department of Agriculture (23 Apr. 2000) Duncan, Bruce (ecologist) Hamilton Spectator Hamilton Region Conservation Authority (Ontario) (27 Aug. 1992) Durkis, Thomas (entomologist) Patriot Ledger (affiliation not specified) (22 Apr. 2000) Ellis, Bob (superintendent) Omaha World Herald Douglas County Weed Control Office (Nebraska) (15 July 2001, 21 June 2002) Ellis, Donna (extension educator and co-chairwoman) Hartford Courant Department of Plant Science, University of Connecticut and Connecticut (13 May 2007, 3 July 2008) Invasive Plant Working Group New Haven Register (22 Feb. 2007) New York Times (13 Oct. 2002) Wall Street Journal (9 Sept. 2006) Faust, Jim (educational adviser) Wall Street Journal Tennessee Flower Growers Association (14 Jan. 1998)

123 Should we care about purple loosestrife? 1991

Table 5 continued Specialist interviewed Reference(s)

Fernley, Dan (manager) Record (New Jersey) Ploch’s Garden Center (New Jersey) (17 Aug. 2002) Firestone, Chris (title not specified) Patriot News Department of Conservation and Natural Resources (state not specified) (19 June 2000) Frein, Maury (manager) St. Louis Post—Dispatch Ahner’s Garden and Gifts (Missouri) (15 June 2002) Gaden, Mike (natural resources agent) Detroit News Michigan State University Extension Office in Howell (7 Oct. 2004) Gibbs, Ann (horticulturist) Portland Press Herald Maine Department of Agriculture (21 June 2002) Gillette, Larry (wildlife manager) Star Tribune Hennepin Parks (Minnesota) (24 June 2001) Gleason, Rocky (botanist) Patriot News Pennsylvania Department of Agriculture (19 June 2000) Glooschenko, Valanne (biologist and wetland habitat co-ordinator) Globe and Mail Ministry of Natural Resources of Ontario (23 July 1990) Toronto Star (10 Aug. 1991) Goulding, Donna (chairwoman) Portland Press Herald Saco’s Conservation Commission (Maine) (27 Sept. 2001) Guilford, Marjorie (biological technician) South Bend Tribune Michigan Department of Agriculture (27 July 2000) Harper, Bonnie (co-ordinator) Star Tribune Minnesota Department of Transportation (12 Sept. 1989) Harper-Lore, Bonnie (ecologist) Record (New Jersey) United States Highway Administration (17 Aug. 2002) Heffernan, Bob (executive director) Hartford Courant Connecticut Nursery and Landscape Association (3 July 2008) Heidel, Kathy (naturalist) Star Tribune Hennepin Parks (Minnesota) (24 June 2001) Hennan, Edward (biologist) Globe and Mail Ducks Unlimited Canada (23 July 1990) Hight, Stephen (entomologist) Toronto Star United States Department of Agriculture (25 Apr. 1992) Hocutt, Grady (retired manager) New York Times Montezuma National Wildlife Refuge (New York) (8 July 1997) Hughes, Ken (landscaper) Connecticut Post (affiliation not specified) (29 May 2007) Hunt, Brandon (weed supervisor) Deseret Morning News Davis County (Utah) (11 Mar. 2007) Husband, Brian (botanist and professor) Cambridge Reporter Department of Botany, University of Guelph (Ontario) (30 Aug. 2001) Jeffery, Erica (manager) Toronto Star Ontario Federation of Anglers and Hunters (23 July 1992)

123 1992 C. Lavoie

Table 5 continued Specialist interviewed Reference(s)

Jenkins, Stephen (professor) Pittsburgh Post—Gazette Biology Faculty, Grove City College (Pennsylvania) (19 June 2000) Johnson, Rick (noxious weed control co-ordinator) Seattle Times Thurston County (Washington) (27 Feb. 1990) Johnston, Mark (deputy director) Colorado Springs Gazette El Paso County’s Environmental Services Department (Texas) (19 July 2007) Kafcas, Ernie (wildlife biologist) Detroit Free Press Michigan Department of Natural Resources (3 Sept. 2008) Kamins, Nicole (title not specified) Chicago Sun—Times Chicago Department of Environment (Illinois) (12 Aug. 2001) Keddy, Cathy (ecologist) Globe and Mail (affiliation not specified) (23 July 1990) Toronto Star (9 Feb. 1991) Kirk, Donald (natural heritage specialist) Kitchener-Waterloo Record Ministry of Natural Resources of Ontario (2 Aug. 1991) Kissinger, Don (urban forestry coordinator) Wausau Daily Herald Wisconsin Department of Natural Resources (26 July 2005) Kiviat, Eric (biologist and executive director) Poughkeepsie Journal Hudsonia Research Institute (New York) (12 Oct. 2003) Klick, Ken (ecologist) Chicago Daily Herald Lake County Forest Preserve (Illinois) (5 Oct. 2002, 24 June 2003) Klironomos, John (botanist and professor) Toronto Star College of Biological Sciences, University of Guelph (Ontario) (2 May. 2002) Kyde, Kerry (invasive plant specialist) Baltimore Sun Maryland Department of Natural Resources (10 Aug. 2006) Laing, John (entomologist and professor) Globe and Mail Department of Environmental Biology and Botany, University of Guelph (Ontario) (12 Mar. 1993) Hamilton Spectator (28 Jan. 1993) Kitchener-Waterloo Record (2 Sept. 1993) Toronto Star (1 Aug. 1994) Lander, Everett (area manager) Toronto Star Ducks Unlimited Canada (10 Aug. 1991) Landis, Douglas (entomologist and professor) Detroit News Department of Entomology, Michigan State University (7 Oct. 2004) Grand Rapids Press (12 Aug. 2007) Lane, Eric (co-ordinator) Rocky Mountain News Colorado Department of Agriculture (30 July 2000) Lane, Pete (agent for agriculture and natural resource development) Dayton Daily News Ohio State University Extension in Montgomery County (18 Sept. 2000)

123 Should we care about purple loosestrife? 1993

Table 5 continued Specialist interviewed Reference(s)

LaRue, Troy (biologist) St. Louis Post—Dispatch Missouri Department of Conservation (24 July 1996) Leahy, Kathy (director) Boston Globe Massachusetts Audubon Society (12 July 2007) Lee, Gerry (chief of habitat conservation) Globe and Mail Canadian Wildlife Service (22 Aug. 1991, 12 Mar. 1993) Hamilton Spectator (24 July 1992) Toronto Star (26 Aug. 1992) Liebman, Matthew (biologist) Boston Globe United States Environmental Protection Agency (15 July 2001) Lindgren, Cory (co-ordinator) Winnipeg Free Press Manitoba Purple Loosestrife Project (27 July 2001, 15 Aug. 2005) MacKay, Beth (biologist) Kitchener-Waterloo Record Ontario Federation of Anglers and Hunters (12 Aug. 1994, 1 Aug. 1995) Toronto Star (1 Aug. 1994) MacKenzie, Donna (biologist) Cambridge Reporter Ontario Beetles and University of Guelph (30 Aug. 2001) Toronto Star (16 Aug. 1997) Malecki, Richard (biologist and professor) New York Times College of Agriculture and Life Sciences, Cornell University (New York) (13 June 1982) Mattson, Jim (biologist) New York Times United States Fish and Wildlife Service (8 July 1997) Mayer, Mark (entomologist) Philadelphia Inquirer New Jersey Department of Agriculture and Phillip Alampi Beneficial Insect Rearing Laboratory (26 Aug. 2007) (New Jersey) Reading Eagle (25 Aug. 2008) Star Ledger (4 Aug. 2001) McAlney, Keith (biologist) Globe and Mail Ducks Unlimited Canada (3 Aug. 1994) McEvoy, Peter (entomologist) Oregonian Department of Botany and Plant Pathology, Oregon State University (9 Oct. 2000) Meeker, Mike (gardener) Oshkosh Northwestern Winnebago County Parks Department (Wisconsin) (14 July 2005) Melvin, Deborah (biologist) Worcester Telegram & Gazette Parker River National Wildlife Refuge (Massachusetts) (13 Aug. 2004) Miller, Ryan (graduate student) Chattanooga Times Free Press Department of Biological and Environmental Sciences, University of Tennessee (23 July 2007) at Chattanooga Motta, Jamie (co-ordinator) Edmonton Journal Alberta Agriculture (17 Aug. 2000)

123 1994 C. Lavoie

Table 5 continued Specialist interviewed Reference(s)

Mountain, Will (botanist) Pittsburgh Post—Gazette Pennsylvania Department of Agriculture (19 June 2000) Nave, Shannon (naturalist) Dayton Daily News Green County Park District (Ohio) (11 Apr. 2002) Neraasen, Terry (biologist) Globe and Mail Ducks Unlimited Canada (23 July 1992) Nicosia, Janet (co-chairwoman) Boston Globe Martins Pond Association (Massachusetts) (28 July 2002) Palmer, Dan (production chief) Star Ledger New Jersey Department of Agriculture and Phillip Alampi Beneficial Insect (4 Aug. 2001) Rearing Laboratory (New Jersey) Wall Street Journal (9 Sept. 2006) Paseuth, Kham Vong (biology student) Record (New Jersey) (affiliation not specified) (26 Aug. 2001) Peterman, Kate (naturalist) Milwaukee Journal Sentinel City of West Bend (Wisconsin) (23 June 2004) Phillips, Floyd (terrestrial quality manager) Globe and Mail Manitoba Environment Department (3 Aug. 1994) Pogacnik, John (natural areas specialist) Plain Dealer Lake Metroparks (Ohio) (14 June 2000) Presley, Jerry (director) St. Louis Post—Dispatch Missouri Department of Conservation (6 July 1989) Prokrym, Dave (biologist) South Bend Tribune Michigan Department of Agriculture (27 July 2000) Quinney, Terry (biologist) Globe and Mail Ontario Federation of Anglers and Hunters (3 Aug. 1994) Toronto Star (23 July 1992, 30 July 1992) Ralph, Dave (weed technologist) Globe and Mail (affiliation not specified) (3 Aug. 1994) Rasy, Michael (pest control specialist) Anchorage Daily News Cooperative Extension Service, University of Alaska at Fairbanks (13 Oct. 2005) Reed, John (co-ordinator) Oregonian Oregon Bureau of Parks and Recreation (22 Sept. 2005) Reiner, Robin (biologist and executive director) Boston Globe Association of Massachusetts Wetlands Scientists (15 July 2001) Riley, Julie (horticultural agent) Anchorage Daily News Cooperative Extension Service, University of Alaska at Fairbanks (13 Oct. 2005) Rubec, Clayton (national co-ordinator for wetlands conservation) Kitchener-Waterloo Record Canadian Wildlife Service (2 Sept. 1993) SaintOurs, Fred (entomologist) Patriot Ledger (affiliation not specified) (6 Aug. 2004) Schmidt, Al (title not specified) Toronto Star Agriculture Canada (26 Aug. 1992)

123 Should we care about purple loosestrife? 1995

Table 5 continued Specialist interviewed Reference(s)

Schneider, Greg (manager) Fort Wayne Journal Gazette Ohio Department of Natural Resources (4 Sept. 2005) Schooler, Shon (entomologist) Oregonian Department of Botany and Plant Pathology, Oregon State University (9 Oct. 2000) Schrum, Gregory (planning chief) Patriot News (affiliation not specified) (19 June 2000) Schulze, Carl (director of plant industry) Record (New Jersey) New Jersey Department of Agriculture (17 Aug. 2002) Scott, Bill (weed director) Wichita Eagle Kansas Department of Agriculture (25 Jan. 2002) Scudder, Tom (entomologist) Star Ledger New Jersey Department of Agriculture (4 Aug. 2001) Sferra, Nancy (director of science and stewardship) Portland Press Herald Nature Conservancy (21 June 2002) Shephard, Michael (ecologist) Anchorage Daily News United States Forest Service (13 Oct. 2005) Sherman, Dave (biologist) Columbus Dispatch Crane Creek Research Station (Ohio) and Ohio Division of Wildlife (3 May 2000) Plain Dealer (14 June 2000) Shinkle, Bob (title not specified) Star Ledger Aquatic Gardens (Alabama) (4 Aug. 2001) Skinner, Luke (co-ordinator) Star Tribune Minnesota Department of Natural Resources (24 June 2001) Smith, Tim (scientist) Worcester Telegram & Gazette Massachusetts Office of Coastal Zone Management (13 Aug. 2004) Snyder, David (botanist) Star Ledger New Jersey Department of Environmental Protection (8 Sept. 2004) Snyder, Jamie (invasive plant specialist) Anchorage Daily News Cooperative Extension Service, University of Alaska at Fairbanks (13 Oct. 2005) Somers, Paul (botanist) Worcester Telegram & Gazette (affiliation not specified) (8 Sept. 1998) Spendiff, Kyle (biologist) Record (New Jersey) New Jersey Meadowlands Commission (17 Aug. 2002) St. John, Joe (co-chairman) Detroit Free Press St. Clair Shores Waterfront Advisory Committee (3 Sept. 2008) Stabler, Rebecca (assistant director) Patriot News Olewine Nature Centre, Wildwood Lake Sanctuary (Pennsylvania) (19 June 2000) Stephenson, Gerry (biologist and professor) Kitchener-Waterloo Record Department of Environmental Biology, University of Guelph (Ontario) (2 Sept. 1993) Suedmeyer, Beth (co-ordinator) Boston Globe Massachusetts Office of Coastal Zone Management (12 July 2007, 27 Apr. 2008, 4 Aug. 2008) Tesauro, Jason (biologist) Record (New Jersey) New Jersey Department of Environmental Protection (17 Aug. 2002)

123 1996 C. Lavoie

Table 5 continued Specialist interviewed Reference(s)

Tewksbury, Lisa (manager) Providence Journal Biological Control Laboratory, University of Rhode Island (20 July 2006) Tomczyk, Richard (watershed specialist) Boston Globe Massachusetts Executive Office of Environmental Affairs (28 July 2002) Trushinski, Brian (environmental co-ordinator) Kitchener-Waterloo Record City of Waterloo (Ontario) (12 Aug. 2001) Varbel, Becky (title not specified) Wichita Eagle DeRee Nursery (Kansas) (25 Jan. 2002) Wagner, Lou (scientist) Boston Globe Massachusetts Audubon Society (12 July 2007) Wallace, Ginny (botanist) St. Louis Post—Dispatch Missouri Department of Conservation (6 July 1989) Wiedenmann, Robert (director) Chicago Daily Herald Center for Ecological Entomology, Illinois Natural History Survey (17 May 2004, 15 Aug. 2004) Woods, Brock (ecologist) Milwaukee Journal Sentinel Wisconsin Department of Agriculture (6 July 2000, 5 Aug. 2002) Wright, Wendy (planning commissioner) Cambridge Reporter Waterloo Region (Ontario) (30 Aug. 2001) Yatskievych, George (botanist) St. Louis Post—Dispatch Missouri Department of Conservation (15 June 2002) Zeller, Michael (biocontrol expert) Pittsburgh Post—Gazette Pennsylvania Department of Agriculture (19 June 2000) Zemke, Rex (forester) Wausau Daily Herald Village of Rothschild (Wisconsin) (26 July 2005) Zimmerman, Tara (educator) Seattle Times Washington State University’s King County Extension (6 Aug. 2004) Press agency newswires were excluded from this survey

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