Invasion study: Testing the roles of taxonomic affinity and species origin in intentional plant introductions using nursery data in Kentucky

Background/Question/Methods

Biological invasions frequently bring about negative impact on natural ecosystems including changing their structure and function and causing losses of biodiversity. Studies have shown that a large percentage of invasive species are introduced intentionally as horticulture plants by the green industry. More than 5,000 introduced species have escaped cultivation and become naturalized to natural habitats in the United States. The repeated introductions of nonnative plant species have accelerated the invasion processes considerably. Currently, there is still a lack of specific information on nonnative and invasive plants in the state of Kentucky, especially in the areas of species origin and the pathway of species introduction. This study is designed to gather information of plant species found in nurseries in Kentucky and to test the following hypotheses using contingency table analysis: there is no relationship between species taxonomic affinity and native origin; there is no origin preference by people when they purchase gardening plants from local nurseries.

Results/Conclusions

By identifying and recording 502 species in 101 families and 258 genera from twenty-two nurseries statewide, we discovered a significant relationship between taxonomic affinity and the origin of plant species; nonnative plant species, especially with eastern Asia origin, are preferred by gardeners in general. Our results suggest that taxonomic affinity and native origin of plant species could be used as an effective indicator in identifying the pool of potentially invasive species in the future. Moreover, our findings validate the fact that nurseries have been one of the major sources of introducing nonnative plants into natural communities as suggested by previous studies. Our study could provide a solid basis for further conservation research on the effects of intentional introduction of nonnative plants in Kentucky and other regions in a larger spatial scale.