Trade routes for commerce in plants or pathways for invasive species? The dualism of international commerce

摘要

The transport of commerce, at any geographic scale, is an on-going trial between costs and benefits. Trade is beneficial to the immediate trading partners, but the benefits for others may be elusive to identify. Furthermore, the fate of many immigrantspecies illustrates that far from benefits, there may be substantial costs to the public from the inadvertent escape of alien plant species through unregulated trade. All nations now have a legacy of alien species that have become invasive. The speed and volume of international trade combined with the highly idiosyncratic views among people as to what constitutes a desirable plant for import means that many more species will enter international trade in the future. Some of these will become invasive. As a result, national plant quarantine services and the recently established World Trade Organization will repeatedly face an old dilemma: what is the appropriate level of restriction to prevent the entry of potentially invasive plants but not unfairly restrict free trade? Although the poles in this debate (complete embargo on trade and no trade restrictions at all) are clear and will be avoided, the appropriate centric position is still poorly perceived. Some international guidelines appear prudent; there is the need to understand the expression of any species' attributes within a specific environmental context along with ample attention to the circumstances upon and soon after immigration. Each nation's application of these guidelines will require much experimentation and a willingness to erect a flexible quarantine framework that can implement improvements as we learn more about how plant entry actually leads to invasion compared with local extinction.