Discussion

This project was designed to identify the attitudes of the nursery industry on invasive plants and develop recommendations for effective programs to reduce the impacts of exotic invasives on the nation's ecosystems. The programs that I directly addressed in the design of my survey as well as the issues that came up in open-ended questions in the survey are discussed throughout this section. I have grouped them into the following subsections:

The Proponents

More respondents felt that invasive plants should be controlled by government than those who did not. And in general, the respondents were willing to take some steps to control invasive plants (Q15, Q20a). About 25 respondents felt that invasive plants are worth controlling, measured by their response to question Q15g (invasive plants should not be plant anywhere) and Q10. These respondents either felt that invasive plants and their regulations did not affect the industry very greatly or felt that the effects were necessary or positive. "It limits our availability of plants," said one in Q10, "But we think it is more important not to continue the spread of these plants to wild places. There are plenty of great plants to grow that don't cause these problems. Some plants are restricted only in some states, and that can be pesky, but we handle it." Another felt that "No one has come to grips with the problem, it needs to be addressed." Yet another acknowledged that "the nursery industry has been the biggest source of invasive plants, mainly exotic species. Sales may decrease for nurseries selling invasives, but many already limit their sales of invasives. [There would be] not much overall change in nursery industry if invasives were eliminated."

The Opposition

13 respondents expressed an anti-control or antigovernment sentiment somewhere in the survey (in Q15 they (8) did not agree or strongly agree with any of the options, others stated it in Q21, Q29, or Q30). 6 more felt that invasives regulations are too extreme (see Results). One felt that "government does not need to tell me any more ways to stop selling product - they want my taxes don't they?" While another said "This discussion needs to be kept away from the media and politicians so that a well thought out plan can be worked out before people who know nothing about the subject put their noses in." Another wanted to "keep government agencies out of my business." Another felt strongly that they did not want to be informed anymore about invasive plants because "this is NOT the most important problem in the industry," which they wrote in a large scrawl across all of the options given in Q28. Yet another was opposed to any attempt to control invasive plants because "Man is part of nature and the natural world wide distribution of plants. Some are invasive. Just as no one stops the birds, no one should stop man." Only one of these 19 respondents agreed that "invasive plants should not be planted anywhere" (Q15g), indicating the other 18 respondents' wariness of the issue.

There was often a conflation of the word invasive with the word exotic by these 19 respondents; they perceived that those who want to control invasive plants "want to do away with all nonindigenous plants." The main strategy to persuade this group will be education and reasoned discourse. They must be won over with facts – that most exotics are not invasive, that creative use of alternative plants can make up for the loss of invasive plants in their palette, and that the invasive plants that should not be used run the risk of causing great ecological damage. At the same time, in order to be persuasive, policies must listen to the nursery industry's complaints and respect them. Involve the industry in creating plant lists; carefully examine each plant for its current and potential ecological damage; and communicate in a clear and understandable way. The Exotic Pest Plant Councils are a current attempt at this, but they have their detractors. Of the Florida EPPC, one respondent said that, "the main problem I see with invasive plant lists I have seen is that at least in Florida no set criteria or guidelines were used to place a plant on the list. At this point it appears that anyone who sees a plant "out of place" can request it appear on the invasive list. This is not the way to support this effort without specific guidelines. Until the invasive councils have solid guidelines or approaches to listing plants and a mandate to create such lists, the industry will have a problem agreeing to invasive plants."

A difficult balance must be struck with reducing the risk of ecological damage and winning the agreement of the nursery industry. Scientific proof of invasiveness is often impossible to obtain proactively. "A plant 'out of place'" may be the only thing a land manager has to go by – if policymakers wait until the plant is causing irreparable damage (as is currently done in adding plants to the Federal Noxious Weed list), they will have missed an earlier opportunity to prevent the damage when it was first noticed as having escaped. Indeed, there is always the possibility that "a plant 'out of place'" will never spread beyond that particular spot and never threaten the native ecosystem. On the other hand, invasive plants often behave much like cancer – they are a small, localized problem at the beginning until the population reaches critical mass and spreads to many other areas, becoming widespread problems (Lowenberg 1998, Campbell 1997). This is where priorities come into play: is our society more interested in maintaining biodiversity or the economic health of nurseries? Some may say that maintaining biodiversity will have little impact on nurseries (37/70 in Q10 felt this way), in which case we need not make the choice. If we feel there is little economic impact or if we feel that biodiversity is of higher importance, then following the precautionary principle is appropriate. When the consequences are large, as it is in this case – we are damaging ecosystems and losing biodiversity, but the scientific certainty is low, the Precautionary Principle directs us to create policies which err on the side of caution (Plater et al 1998). Scientific certainty is low. As Faith Thompson Campbell (1997) puts it, "We should be humble; we may never fully understand the invasion process, particularly for each of the hundreds of potentially invasive species in each of our many ecosystems. One truth is clear: as time passes, many species will spread to new areas or increase in density if controlling actions are delayed." Putting "out of place" plants on plant lists is, in most cases, the only way weed scientists have been able to create effective prevention programs because scientific proof is difficult to come by (Parker and Reichard 1998; see Results for the industry's desire for scientific proof).

The closest thing to scientific certainty may be expert opinion, and this may help persuade some industry members that the plant lists are credible. According to Sarah Reichard, a horticultural ecologist who works on this issue in Washington state, the state invasive plant list is made according to expert opinion and it is generally well received (Reichard, personal communication). While the one respondent from Washington did not tell me what they thought of the state's policies, they did tend to be skeptical of invasive plant policies, saying that "maybe some so-called ecosystems need to be invaded," and "I have a problem with some peoples' ideas of harm (especially environmental harm)."

Those who felt that invasive plant policies are too extreme tended to conflate the meanings of invasive and exotic, as I have said above. These respondents seemed to have a fear that Michael Pollan expresses in the New York Times in 1994 in an article called "Against Nativism." He argues against gardening with natives, promoting "horticultural multiculturalism." Saying that "it's hard to believe that there is nothing more than scientific concern about invasive species behind the current fashion for natural gardening and native plants – not when our national politics are rife with anxieties about immigration and isolationist sentiment." Citing the nature gardens of Nazi Germany (Wolschke-Bulmahn and Groening, 1989 and 1992), Pollan calls the natural gardening trend "xenophobic" and argues that a few bad-actor alien species (kudzu, Japanese honeysuckle, multiflora rose and purple loosestrife) are used to brand all exotics with a bad image. Many nurseries tend to agree, believing that those who wish to control invasives are promoting their own "agenda" or natural gardening.

The key to overcoming this argument, however, is stated right in Pollan's article: "In fact, the great majority of introduced species can't survive beyond the garden wall, much less thrive." Most exotic plants are not invasive. Policies to ban all exotics would be unreasonable and unfeasible – most food, fiber, and horticultural crops are exotics. They are permanent fixtures of our way of life. We rely on exotic plants for erosion control, ecological restoration, and as urban street trees, where exotics are often disease and pest resistant. Many nursery industry members are understandably cautious about plant restrictions; plant-restriction proponents have varied objectives, some with more inclusive lists than others. Yet again, involving the industry in policy creation will calm some of these fears. Education and media coverage can help this. Others may be persuaded by consumer pressure (9/19 who seemed to be anti-control, said that consumer or natural history group pressure would persuade them to stop selling invasive plants while 10/19 said that government prohibition would persuade them, 4/19 said both requests and prohibition would).

The view that invasive plants are controllable is illustrative of a common sentiment in the industry – plants that can be controlled should not be regulated, while those that cause significant environmental harm should be. Unfortunately, there is often overlap in these two categories – one of perception. As the Office of Technology Assessment (1993) report on nonindigenous species points out, which species to regulate "are ultimately cultural and political choices – choices about the kind of world in which we want to live." In a gardener's or nursery's own experience, a particular plant may not be invasive – indeed, the plant may seem to be a "good plant" (a term used often by respondents) for any number of reasons. But never seeing a plant spread within one's own garden may not reflect the plant's behavior elsewhere. In addition, the natural areas close to a nursery may have entirely different ecology than the growing area of the nursery. In short, just because a gardener never sees a vine spread into the forest does not mean it did not happen. Controllable plants can become pests, especially when these controllable plants are sold by many nurseries.

Some gardeners may be fully conscious of the plants' effects and yet still feel that they can prevent its spread outside of the garden. Gardeners who feel that they can control invasive plants are demonstrating a certain arrogance which stems from a common ignorance and doubt – it is not clear to anyone what the consequences are of planting an invasive plant in a single garden. We know that most escapees were originally garden plants, but how many tries it took until those plants escaped is impossible to know. The important thing is that plants escape from gardens – there is always a risk that a plant will invade a natural ecosystem and threaten the native system. If we are to follow the Precautionary Principle, just knowing that there is any risk of a very serious effect (the loss of biodiversity) is enough to justify discontinuing that planting any nonindigenous plant with invasive potential. This potential could be determine using Reichard's decision tree or another form of risk-analysis.

It is rare to see the direct result of one's own irresponsible environmental behaviors. Planting invasives is yet another example of the obscured effects of a behavior, in a world often devoid of consequences (consumers, for instance, rarely see the social and environmental consequences of their purchasing choices). It is also an example of Garret Hardin's (1968) tragedy of the commons – the effect of an individual's choice to plant in invasive in their garden is insignificant, while the effect of many is quite large (25/77, 32% of participants admitted they had planted an invasive plant), especially when a few of those many are not conscientious about preventing their plants from spreading.

Government Programs

The nursery industry has some common complaints on and suggestion for invasive plant policies. They would like policies to be more regional and site conscious than political-boundary conscious; policies to be enforced and implemented more effectively; more scientific proof justifying the decisions; see justification behind invasive plant lists; and to give more input to the policies (see Results).

None of the regulatory/programmatic options provided to participants in my survey (except, perhaps, Q15f, "invasive plants should not be planted near natural areas") takes "into consideration the vast differences in ecosystems across the USA," as one respondent pointed out. However, these questions are meant to gauge the willingness of the industry to be regulated under a conventional framework, by political boundaries. Unfortunately, the regulation of ecological problems must take ecologically-arbitrary political boundaries of states and nations into account. Exotic Pest Plant Councils in the Southeast and Northwest are attempts to work at a regional level, but even then ecosystems do not obey anthropocentric borders. Creative work in other environmental fields has been done at a watershed-level, which can divide the landscape up on many different useful, ecosystem-conscious scales. Regulation and its implementation, however, must obey political boundaries. While this is not ideal, it can work well. In addition, when dealing with an issue of interstate and international commerce (for this is what the movement of exotic horticultural species is), the Federal government is in the best position to regulate the issue - constitutionally and practically (Interstate Commerce Clause, US Constitution: Article 1, Section 8, Clause 3).

Screening

Screening new plant species as they enter the country is a practical compromise between the industry's desire to introduce new species and conservationists' desires to prevent new invasions. Most of my respondents agreed that screening was an important activity, and many preferred it to outright prohibition and removal from ecosystems (Q15d). Through screening, a federal agency or the importer would analyze every new plant species entering the country for traits of invasibility and then decide whether the plant was "clean" (permissible), "dirty" (prohibited), or "grey" (needing further testing). The agency currently monitoring imports of plants is the Animal Plant Health Inspection Service (APHIS), a division of the US Department of Agriculture. At least one importer already screens his plants – Daniel Hinkley of Heronswood Nursery in Washington state (not a survey respondent) does its own screening through consultation with ecologist Sarah Reichard and a model that she has developed to determine invasiveness (Klinkenborg 1999). Most imports these days are through public botanic gardens or arboretum, which are perfect candidates for screening plants – some botanical gardens have already decided to take on this role (Reichard and White 2000). Sarah Reichard (1997) has developed a model that uses the traits of the new species and compares them to the traits of other known invaders. Her criteria are structured into a decision tree which ultimately groups plants into clean, dirty, and grey lists. These criteria include invasion in other parts of the world, membership in a family or genera already invasive in North America, fertility, ability to spread vegetatively, short juvenile period, and/or seeds not requiring pretreatment. She recommends that those plants falling on the "grey" list should be monitored for at least five years before they are released publicly.

Currently, APHIS does not screen new plant imports, and only includes 96 plants on its "dirty" list – the Federal Noxious Weed list – while at least 750 qualify (Reichard 1997). Current pending legislation, Senate Bill 910 and House of Representatives bill 1504, strengthens importation laws such that the Secretary of Agriculture may implement screening rules. Section 102 of S910 states that "The Secretary may prohibit or restrict the importation, entry, exportation, or movement in interstate commerce of a plant, … noxious weed, … if the Secretary determines that the prohibition or restriction is necessary to prevent the introduction into the United States or the dissemination of a plant pest or noxious weed within the United States." This bill has been pending in some form for about ten years; it is the result of years of compromise between the agriculture industry, nursery industry, government agencies, and conservationists. As it is not a highly controversial bill, it is likely to pass if it comes to a vote (see Policies).

Prohibition

The most effective way to prevent invasive plants from spreading is by banning their sale and importation altogether. While most respondents felt strongly that new plants should be screened (I did not ask whether they should be prohibited), nearly the same proportion felt that current invasives should not be imported - but they were more likely to agree less strongly about this (Q15g, Q15a). Respondents also tended to feel that the Federal government should be responsible for preventing invasive plants from entering the country (Q16). By contrast, respondents were less likely to agree that these plants should not be sold anywhere in the country if they had already gotten here (Q15b). However, these plants should be regulated, most felt, by state government (Q17). The responses were evenly distributed from agree to disagree when they were asked whether plants that are already invasive should not be sold in the United States. They tended to agree, however, that plants invasive in their state should not be sold in their state (Q15c), indicating that the respondents tended to feel that regulations and prohibitions were more appropriate on a local level rather than a national level, unless the national regulations dealt with importation (see Policy).

Eradication

Nurseries also tended to agree that invasive plants should be removed from natural areas. 20 strongly agree and 20 agree that invasive plants should be removed from the ecosystems where they are invading (Q15e). While nurseries and landscapers are not directly affected by plant removal programs – they are not responsible for removing the plants and it does not require them to change their sales practices – their relatively more indifferent view of removal (few disagreed, but those who agreed with it agreed with it less strongly than with screening) appears to show that they believe that prevention is at least as effective as removal.

Voluntary programs for the industry

Industry conformity is an important part of effective invasive plant programs – if not all nurseries restrict their plant sales, then there is still a chance that invasive plants can escape and invade. Only about a third of respondents said that knowing that other nurseries were "doing the same thing" and also restricting their sales would persuade them to stop selling invasive plants (Q21g). When programs are voluntary, however, there is always a risk that a few – or many – nurseries will not follow along, and the program will not reach full efficacy. Strategies more persuasive than mere peer pressure are necessary to achieve high compliance rates. According to the Office of Technology Assessment (1993), "Generally, voluntary approaches for environmental compliance are receiving increased attention for a number of problems. Industry groups often support such initiatives, claiming that voluntary programs are more effective and cut costs. Few environmental groups have endorsed voluntary programs, however."

Effective voluntary policies must take their monetary impacts on nurseries into account. Expensive policies (especially donating money to research) will not be popular and will be difficult to implement. Incentives (or cost coverage by government agencies or industry associations) for nurseries and landscapers who take part in invasive plant programs may increase participation rates and the efficacy of such programs. One respondent had a suggestion along the same lines (Q30), "Nurseries are business that can be slow to change because of the natural for producing crops and the money available for new product introduction. If there was an effective efficient governmental program to distribute Euonymous 'Rudy Haag' (a variety of burning bush that is minimally invasive). The nurseries could afford to and in a timely manner replace the production of the straight species of burning bush." (See New Cultivars section in this page.)

Creative policies elsewhere in the world have helped control invasive plants without putting the financial burden on nurseries. In Manitoba, there has been a program to dig up purple loosestrife in gardens and bring it to the Manitoba Weed Supervisors in exchange for native flowers (Lowenberg 1998; Cory Lindgren, personal communication October 7, 1999).

Certification

One possible program promoted by the nursery industry could be a form of certification. Independent parties would inspect nurseries and determine whether or not they qualified for an invasives-free certification. Reichard and White (2000) asked gardeners and nursery customers whether they would prefer to shop at "forest friendly" certified nurseries; 68% said that they would "quite a bit o very much", while 31% said that they would not. 19/71 (27%) said that they would be persuaded to stop selling invasive plants by participating in a certification program (Q21d). These respondents tended not to feel that customer requests would persuade them to stop selling invasive plants (only two felt they would, Q21e).

Labeling

Rather than outright bans on invasive plants, which is considered extreme by some members of the nursery industry, labeling plants as invasive or as alternatives to invasives might be a more well-received activity by the industry, especially because it is less likely to have a large impact on their sales. WHile it is unclear that either activity will be very expensive, labeling is perceived as having less impact because it does not force nurseries to change their sales and potentially lose customers for a particular plant. Instead, labeling allows customers to make informed decisions about their purchases and affect the market through consumer pressure. Labeling, however, does not prevent those customers who "do not care" about invasive plants (Q22) from buying them when they are set on them. 30/76 respondents were willing to use warning labels on invasive plants (Q20i), while 33/76 were willing to label plants as alternatives to invasives (Q20j). Only 2 respondents who were not willing to use warning labels but were willing to label alternative plants. Generally, the willingness to use warning labels was correlated with the willingness to use labels on alternatives as 25 respondents were willing to do both (Spearman's rank of 0.6470, p<.00005). Chances are, however, that if a nursery is willing to use a warning or alternative plant labels, it is also willing to remove plants from its stock (Q20a), in which case labels are unnecessary (25/30 who were willing to using warning labels were willing to remove plants from their stock, while 25/33 who were willing to use alternative labels were also willing to remove plants from stock). Of the 5 respondents who said that "no" they were not willing to remove invasive plants from their stock/plant palette (Q20a), 2 were willing to use labels, so it is possible that labels may appeal to less accommodating nurseries and landscapers. Labels are unnecessary except, perhaps, for those cases in which plants that are considered invasive by some but have not been banned (as would be the case if the Australian model were followed where plants were ranked for their invasiveness with only the most invasive plants banned). Including botanical names on plants is an easy way to aid customers in making informed choices. Labels are also likely to influencing customer buying patterns. Only 2% of Reichard and White's (2000) customer respondents said that they were very likely to buy a plant that was labeled invasive.

Nearly all of my respondents already use or are willing to use botanical names on their plant labels (Q20k). This is one key step toward making sure that the informed customer can avoid invasive plants. Because common names are often interchangeable and misleading, including botanical names lets customers confidently identify their plants. Government or industry mandate to use botanical names may be fairly uncontested and simple to implement. In order to enforce the use of botanical names among the small number of nurseries that do not already use them, a spot inspection program with fines for noncompliance. The Australian plan points out that "space on labels is at a premium and the inclusion of botanical names is not a high priority no matter how small the font." It then encourages the cooperation of label manufacturers, catalog editors and nurseries importers. However, many customers are not informed, so proper plant labeling alone cannot be a panacea – nor is it enough to consider a nursery responsible. Customers must become aware of the problem in order to start avoiding particular plants.

Education

In their study of customer preferences, Reichard and White (2000) found that 83% of customers would like to avoid buying invasive plants. The key to making sure that these customers can exercise their preferences is education. The respondents to my survey indicated that they were willing to take an active role in educating their customers about invasive plants. Most were also interested in further education for themselves. Increased education will make a difference because most customers are interested in avoiding invasive plants; but education alone will not solve the problem of horticultural invasive plants - it must be paired with programs preventing introductions and plant restrictions because the 17% of customers who will not avoid invasives can still spread the plants.

Voluntary Restrictions

A common argument against removing an invasive plant from nursery stock is that the nursery will lose customers who would seek this plant out. Reichard and White (2000) found that 92% of customers would definitely not seek out invasive species at another nursery if their nursery did not carry it. Only 8% said that they would sometimes or very often go elsewhere. Their findings indicate that nurseries that chose not to carry invasive plants will experience a very minimal – if any – impact on their revenues.

Of those who responded to Q20a and felt it was applicable to them, 93% said that they were maybe or definitely willing to remove invasive plants from their stock (29% said maybe), while only 7% said that they were not. This question is an encouraging indication that the great majority of nurseries are interested in selling non-invasive plants, but may need to be further educated in order to be persuaded to do so. Reichard and White's (2000) finding may persuade the "no" and "maybe" respondents to remove plants.

Donations

The least popular programmatic option presented to my respondents was donating proceeds to research on invasive plants (Q20e). While research programs are considered necessary – indicated by the high priority they place on scientific proof of invasiveness, and while a few respondents considered the lack of funding a hindrance to government efforts to control invasive plants, few industry members seem willing to contribute their own money. Willingness to donate money does not correlate with the income of the nursery; those who said that they were willing fell into all three of my sales cohorts (Q8).

If nurseries are not willing to donate their proceeds to run invasive plant programs, they must be willing to tolerate some governmental involvement in the issue, yet of the 8 who were willing to donate money, none seemed to express an anti-government sentiment in the survey. Of the 8 respondents who expressed an anti-government sentiment in Q30 or who did not agree to any of the programs in Q15, only one said that they were maybe willing to donate money to research; 1 did not answer Q20e and the remaining 6 said that they would not donate money.

New Cultivars

One role of education on this issue is to inform nurseries and landscapers of the alternatives to invasive plants, thereby encouraging them to avoid using invasives. Many of my respondents expressed an interest in learning about or developing new plants to be used as alternatives to invasives (see Results). This is another encouraging result, as others working on policy recommendations have included developing alternative plants and the industry seems receptive to this option (Reichard 1997, Australian plan 1998). However, research into native and noninvasive alternatives should be a priority over developing sterile cultivars because it has been shown that some, specifically Lythrum salicaria (purple loosestrife), can often revert to fertility through breeding with naturalized plants (Meier 1999).

Because most of my respondents reported that they put a high priority on the environment (Q14), most of them may be persuaded to change their behavior – if they make the connection between the plants that they sell and ecological harm, that is. Making this connection is the difficult part. Of the 19 respondents that I classified as "anti-government" or "anti-control", their average environmental priority was 1.58, meaning they tended to have a higher self-reported environmental priority than the 25 pro-control respondents, who had an average environmental priority of 1.78. The 19 anti-control respondents will probably be the most difficult group to persuade to change their behavior, so appealing to environmental conscious may be a pointless effort for them, while it would be important for the rest of the industry that is willing to change, but uninformed about invasive plants.