Biology Reference
In-Depth Information
suspected of such origins (Fox et al. 2003). This phenomenon is not unique to the
USA. Mack and Enberg (2002) found that 65% of invasive plants introduced into
Australia between 1971 and 1995 were introduced as ornamentals. Thus, the
ornamental horticulture industry unwittingly introduced invasive NIS to market.
This is not a recent phenomenon. While some plant species were imported into
North America for ornamental purposes prior to the seventeenth century, aesthetic
plant importation was most evident in and after the eighteenth century (Mack
2003): By 1860, imported ornamental plant species significantly outnumbered
imported utilitarian species (Mack and Enberg 2002).
One of the most lucrative areas of ornamental plant sales is new plant introductions.
This is evidenced by the emergence of many nursery businesses whose major market-
ing focus is novel plant introductions. Additionally, the American Nurseryman (1999),
a leading trade journal for nursery and landscape professionals, devotes an entire
bimonthly journal issue each year to new plant introductions. While no quantification
of the nativity or residence time in the USA of these introductions has been made, the
new-to-the-trade plant phenomenon stimulates efforts to seek out new introductions,
many from outside the USA, and yield substantial profits. A quick glance at most gar-
den plant catalogs and mail order web sites verifies this trend. Internet-based sales of
ornamental plants are now a sizeable provider of garden plants, which facilitates the
importation of NIS. Dave's Garden - Garden Watchdog (Dave's Garden - Garden
Watchdog, http://davesgarden.com/products/gwd/. Accessed 23 May 2008), an inter-
net site directory of gardening (plants and plant-related items) mail order vendors lists
6,257 businesses, most of which have a web site. Internet sales of NIS are sources of
invasive, potentially invasive, and even some illegal plant taxa (Clayton 2004). To halt
the sale of prohibited invasive NIS on the internet, researchers from North Carolina
State University and the USDA have developed Web application software that searches
the Internet for vendors who sell illegal invasive NIS (NC State University News
Release 2003). One would assume that imposing strict limitations on new plant intro-
ductions, especially those that are likely to become invasive (determined via screening
procedures) or carry nonnative pests and pathogens, would increase our success rate in
preventing the release of invasive NIS. However, Simberloff et al. (2005) point out two
limitations to this assumption. First, there is a great divergence in opinion on the
impact of invasive NIS between stakeholders. Embedded in these differences of opin-
ion are the conflicts of interest of the regulatory agency tasked to govern the flow of
NIS (USDA), which ironically is funded, in part, by the tax money generated by the
sale of NIS. Second, the central aspects of risk assessment, predicting specific negative
consequences and estimating their probability, are greatly affected by the unpredicta-
bility of impacts of introduced species.
Members of the ornamental horticulture industry recognize the need for action
regarding invasive NIS. Hall (2000) surveyed ANLA members and found the fol-
lowing results: (1) Sixty-eight percent of respondents were in favor of the govern-
ment screening new NIS introductions. However, respondents wanted policies to be
more regionally directed than political boundary directed, to have a more effective
enforcement and implementation of policies, and have more scientific proof justify-
ing decisions and species placed on invasive lists. (2) Over half of the respondents
