Controversy
Controlling invasive
plants is a politically and emotionally charged topic in the horticultural
and ecological worlds. As the Office
of Technology Assessment (1993) states, the decision
of "which species to import and release are ultimately cultural
and political choices - choices about the kind of world in which we
want to live." Society, and specifically the society of plant-interested
people, is not homogenous, which means that the idea about the kind
of world we should live in - and why - is quite varied. Conservationists
want to preserve biodiversity while nursery professionals want to
preserve their freedom to choose and sell a diverse array of plants. Preservationists want to maintain pristine natural areas
while others feel that invasion is natural and not an important environmental
battle to pick. Interestingly, most people who care about this issue
agree that the environment is worth protecting; they just disagree
on whether plant invasions are a detrimental or significant impact
on the environment (see the Results of
my survey). One large conflict
results from the fact that the “movement” to prevent plant invasions is so
closely tied to the native plants movement. Prominent ecologists in the field
are quite concerned about native plant preservation and are often important
members of native plant organizations. "Natural gardening" is a
current popular trend tying gardening practices to environmental ethic, and
by extension, promoting the use of native plants (Pollan 1994). Detractors
from the natural gardening movement and the anti-invasives movement have
accused them both of being xenophobic. A common misconception of the term
“invasive” is that it applies to all non-native plants. People who value the
aesthetic and practical benefits of non-native plants have been known to cite
Hitler’s request of Germans to plant only native German plants in order to
support their ideas that native plant lovers are extremists (see Groening and
Wolschke-Bulmahn 1989 & 1992). The nursery industry has voiced many objections to invasive plants law that have been elaborated by Reichard and White (2000). Detractors of invasive plant controls often mistakingly believe that regulation to limit plant invasions would prohibit the importation of all new non-natives (Pollan 1994). This is a common misconception, which is a misconception because only about 0.2%-15% of all exotic invaders become established in natural systems (Lowe 1998, OTA 1993, Thompson and Brown 1986 in Reichard and Parker 1998), so plenty of exotic ornamentals will still be available for sale. Nurseries also often object
to discontinuing the sale of invasives because they don’t believe
invasive plants are actually a problem, on a number of counts. One
argument is that invasive plants only invade disturbed areas, so they
are actually a benefit to ecosystems that are damaged by human activity.
This argument is false on two counts. First is that even though invasive
plants invade disturbed areas in many cases, they are still displacing
native vegetation and disturbing natural ecosystem processes. In this
way, they are still a threat to biodiversity – they can often
alter the ecosystem such that native secondary successional species
are not able to move into an area. Secondly, invasive plants do not
only invade distrubed areas. As with Hedera
helix (English Ivy), some
plants are able to invade intact ecosystems, thereby displacing natives.
Some nurseries also do not believe that invasives are really a problem because they believe that invasion is a natural process, and therefore should not be disturbed (see Lowry 1999). These people might ask, as the world's peoples become more easily linked through faster transportation and a ever-growing global economy, isn't biological migration inevitable? Aren't attempts to stop bioinvasions futile, in the long run? Isn't the world becoming more homogenous, socially, culturally, and biologically, anyhow? Unfortunately, the world is becoming more biologically homogeneous, as biodiversity is threatened by habitat destruction, invasive species, pollution, overexploitation, and disease (Wilcove et al 1998). Invasive species are the second biggest threat to biodiversity according to Wilcove et al (1998), and they are spreading at an increasingly fast rate - a rate which can be slowed down by sensible regulations and industry programs. The objection that invasion is natural was raised by one vociferous respondent to my survey, who said that "just as no one stops the birds, no one should stop man." Invasion is a natural process, but it is no longer occurring on a natural scale. Another protest against invasions is that invasive plants are not only exotic; native plants can be invasive too. This too is true, but it is not a valid argument against invasive policies. When native plants invade a new (disturbed) part of their ecosystem, they are not a threat to biodiversity, because they are adapted to the system and are therefore a natural part of the successional process. Nurseries have also been opposed to policies that restrict their plant sales because they feel that they are bad for the industry - this is not the case, as long as the nurseries are willing to capitalize on the new opportunities created by plant restriction for new, alternative plants. In fact, one of my survey respondents stated that one of the effects of invasives on the industry would be "a tremendous opportunity for marketing replacement plants." The last argument against invasive plants policies is that some gardeners and nurseries feel that invasive plants can be planted responsibly. This is true up to a point. As soon as the "responsible" gardener who knows about the plants invasive characteristics is out of the picture (moving away, giving away cuttings or transplants, going on vacation), the plant has the chance of becoming a problem. There have even been email-joke-forwards describing how to exact revenge on your neighbors by intentionally planting Pueraria lobata (kudzu) on your property line so that it may escape into their yard and wreak havoc. Some plants simply cannot be planted responsibly. Celastrus orbiculatus (Oriental bittersweet) is an invasive vine on the East coast that bears attractive fruit in the fall that is eaten by birds and then may be planted in new loacations. Gardeners, no matter how diligent, cannot control for natural processes, most of which rule the world of plant invasions. At least 5 of my respondents voiced this view when they were asked why they had planted invasive plants in their own garden (Q13). |
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