Biology Reference
In-Depth Information
were willing to participate in programs to educate themselves, and almost one-third
of the respondents were willing to actively educate (e.g., hold workshops) their
customers. (3) Sixty-four and 29% of the respondents said they would definitely or
maybe, respectively, remove invasive NIS from their stock. (4) Over half of the
respondents were willing to have new, noninvasive cultivars to replace invasive
NIS. (5) About a third of the respondents said that they would stop selling invasive
plants only if they knew that other businesses had stopped selling invasive NIS.
This last finding is suggestive of limited nursery participation in the event of a vol-
untary system for banning the sale of invasive NIS.
The public is generally unaware of the negative ecological and economic
impacts of invasive NIS (Colton and Alpert 1998). However, surveys have found
mixed evidence for awareness of the gardening public about invasive garden NIS
(Wolfe and Dozier 2000; Kelly et al. 2006). In an Internet survey of gardeners,
Reichard and White (2001) came to the conclusion that, “Because the preference to
buy noninvasive species is correlated with familiarity, as the general plant-buying
public becomes more aware of invasions, nurseries and the seed trade industry will
have to alter their practices to ensure that invasive species are not sold.”
9.4
Why Should the Horticultural Industry Care
about Nonnative Species?
The very nature of the ornamental horticulture industry (selling, transporting, and
cultivating NIS) has the potential to foster the invasion process. One of the most
important factors that contribute to an area being invaded is invasion pressure, i.e., the
large numbers or frequency of introduction of NIS (Lockwood et al. 2005; Von Holle
and Simberloff 2005). Supporting the invasion pressure contention and emphasizing
the role of the ornamental horticulture industry in invasion pressure, Pemberton
(2000) investigated the naturalization rate of NIS related to the number of years a NIS
was sold in the nursery trade; he found that the rate of naturalization increased as the
period of sale increased. For example, only 1.9% of plants naturalized that were sold
for 1 year, whereas 30.9% of plants naturalized that were sold for 10 years or more.
Once sold, garden plants are cultivated. This cultivation is an important process in
overcoming the environmental resistance to invasion and favors the invasion process
(Kowarik 2003; Mack 2000, 2005). Additionally, desirable garden plant characteris-
tics, such as a fast growth rate, abundance of fruit, and tolerance of poor growing
conditions (e.g., drought, poor soil), are also characteristics of successful invaders.
Mack (2005) contends that the horticulture industry is in a favorable position to
devise a flexible, rapid, science-based system to screen NIS for invasiveness, which
could help mitigate its role in supporting the process of invasion.
Another reason why the NIS issue requires attention by the ornamental horticul-
ture industry is the previously mentioned phenomenon of “lag time,” the initial
period of a slow spread rate prior to exponential rate of spread. Thus, without
a predictive analysis performed for invasive potential of each species prior to
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