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CHRYSALIS: The Murray State University Journal of Undergraduate Research ABSTRACT Back, l-r: Jacqueline Hawes, Sara Struve, Erica Ludtke; front, l-r: Sanda Thomason, Nicole Zelesnikar; not pictured: Laura Gossett and Jami Kara Hitch Laura Gossett Jacqueline Hawes Jami Kara Hitch Erica Ludtke Sara Struve Sanda Thomason Nicole Zelesnikar As biology majors taking Bio116 in the Fall of 2006, we carried out a study on species taxonomic affinity and their native origins using nursery plants. Studies have determined that invasive species can have negative effects on our natural ecosystems, and most invasive species are introduced intentionally through nurseries. We hope that our research project could help increase society’s awareness of biological invasion and the significance of native ecosystem conservation. Horticulture, a Key Source of Introducing Exotic Species into Native Communities Studies have shown that invasive species can have negative effects on natural ecosystems. Currently, there is a lack of specific information on exotic and invasive plants in the state of Kentucky. This project was designed to gather information on plant species found in local nurseries in western Kentucky and to test the following hypotheses: there is no relationship between species taxonomic affinity and native origin; and there is no origin preference by people when purchasing gardening plants. By identifying all species found in the local nurseries, we discovered a significant relationship between taxonomic affinity and the origin of plant species; and exotic plant species, especially of eastern Asia origins are preferred by gardeners in general. We concluded that species taxonomic affinity and native origin could be used as an effective indicator in identifying the pool of potentially invasive species in the future. This project could help increase society’s awareness of biological invasion and the significance of native ecosystem conservation. FACULTY MENTOR Kate S. He is an assistant professor in the Department of Biological Sciences. She received her Ph.D. from University of Western Ontario. Her research interests are in the broad areas of plant ecology with emphasis on statistical analysis of patterns and processes of plant communities in time and space. Her current research is centered on the study of the impact of invasive species on native ecosystems. She teaches courses in Botany, Quantitative Ecology, and Introductory Biology. She also mentors undergraduate students in her research laboratory. 16 CHRYSALIS: The Murray State University Journal of Undergraduate Research Horticulture, a Key Source of Introducing Exotic Species to Native Communities and Ecosystems E xotic plant species are also called alien plants, non-indigenous plants, and introduced plants in the literature. According to Pysek et al. (2004), exotic plants are defined as plant species in a given area whose presence is due to intentional or unintentional human involvement. Without direct human intervention, some of the non-native species are capable of independent growth and sustain self-replacing populations for at least ten years. Such plants We decided to study plants in our local nurseries. As the literature suggests, a substantial number of plant species, especially woody plants, have been intentionally introduced into new locations through nurseries and botanical gardens (Reichard and White 2001). Furthermore, by collecting data at local nurseries, we can evaluate customers’ preference for native versus exotic species. Our null hypotheses were that there is no relationship between are categorized as naturalized plants. Among the naturalized plant species, about 10% or less could become invasive in the introduced habitats (Williamson, 1996). Here ‘invasive’ means that plants produce reproductive offspring, often in very large numbers, and thus have the potential to spread over a large area (Pysek et al., 2004). species taxonomic affinity and origin and that there is no origin preference by people when they purchase gardening plants from local nurseries. The impact of invasive plants has been observed in major natural ecosystems (Baskin 2002). Typically, plant invasion can change the niches of native species in the communities, alter the structure and function of ecosystems, and disrupt the evolutionary processes (D’Antonio and Vitousek, 1992; Williamson, 1996; Mack et al., 2000). According to Pimentel et al. (2000), it is estimated that in the United States alone more than 137 billion dollars is spent annually on combating biological invasions. Thus, the study of invasive species and their impact on the native ecosystems has emerged as one of the crucial areas of biological research. In the state of Kentucky, plant invasion has become one of the critical tasks for conservation management. About 90 invasive plant species have been listed by the Kentucky - EPPC (Southeast Exotic Pest Plant Council, 2000). However, there is lack of a systematic research on exotic and invasive plants in the state, especially in the areas of the species origin and the mechanisms of species introduction. This project was designed to gather information on plant species found in local nurseries in western Kentucky to: (1) identify species origin; (2) study species taxonomic affinity, i.e., to determine plant family, and (3) determine if relationship exists between species taxonomic affinities and their native origin. Methods To test our hypotheses, we collected plant data from four local nurseries in the vicinity of Murray, Kentucky. The nurseries included Wal-Mart, Lowes, Rolling Hills, and the Wyatt Farms. Each plant species found in the nurseries was recorded and identified to species level. Taxonomic affinity was also examined at the family level for each plant. The independent variable, native origin was identified for all 124 exotic species. The dependent variable, total number of plants per family, was determined and recorded. StatView software was used to perform chi-square analysis to determine whether or not the null hypotheses were supported. Results There was a total of 183 plant species found in the four local nurseries. The total number of native species proved to be much lower than the number of exotic species. There were fifty-nine (32%) native plants while there were one hundred and twenty-four (68%) exotic species (Figure 1). Information on species native origin is shown in Figure 2. The native origins of the plants are identified as seven main geographical areas around the world, which included Europe, eastern Asia, Africa, United States, India, Central and South America, and the Australia/Pacific area. By percentage, the largest groups of plants came from eastern Asia and the smallest percentage came from the Australia/Pacific area. 17 CHRYSALIS: The Murray State University Journal of Undergraduate Research Number of species 160 7% Central and South America 4% India 120 2% Australia/Pacific area 16% Europe 5% Africa 80 40 0 Native Exotic 32% United States 34% East Asia Species Origin Figure 1. Total number of exotic and native plant species found at four Murray nurseries. Table 1 Top eight families with most native species. Family Name Number of species Violaceae 9 Cupressaceae 8 Hydrangeaceae 7 Pinaceae 6 Rosaceae 4 Ericaceae 4 Juncaceae 3 Cactaceae 2 Table 2 Top eight families with most exotic species. 18 Family Name Number of species Cupressaceae 11 Araceae 9 Aquifoliaceae 8 Lythraceae 7 Laminaceae 7 Asteraceae 7 Brassicaceae 7 Rosaceae 6 Figure 2. Information of native origin of plant species found at four Murray nurseries. As shown in Table 1, our results indicated that the Violet family (Violaceae) had the most number of native plants with a total of nine species; and the Cypress family (Cupressaceae) obtained the highest number of exotic plant species with eleven (see Table 2). The results of chi-square analyses revealed: (1) there is a significant relationship between taxonomic affinity and the origin of plant species (p< 0.0001) and (2) exotic plant species are preferred by gardeners in general (x2 = 23.08 > x2 a = 0.05, df =1 = 3.841). Discussion The results of our research show there were more than twice as many exotic than native plants found in the local nurseries primarily due to human preferences on gardening species. This finding is consistent with other research studies. Nurseries have been one of the major sources by which exotic plants are introduced into natural communities (Reichard and White, 2001). Among the exotic species found in Kentucky, a few have made negative impacts on native ecosystems by endangering and replacing native species, resulting in a loss of biodiversity. Typical invasive plants found in the local area are Japanese honeysuckle (Lonicera japonica), Chinese privet (Liqustrum sinense), oriental bittersweet (Celastrus orbiculata), multiflora rose (Rosa multiflora), and tree of heaven (Ailanthus altissima). Unfortunately, some of these species are still sold in the local nurseries. Therefore, it is important to increase society’s awareness of biological invasion due to its negative impact on our native ecosystems. It is even more critical to have informed and educated nursery staff and gardeners, so that invasive exotic species will not be introduced and purchased at the nurseries in the first place. CHRYSALIS: The Murray State University Journal of Undergraduate Research Our study also pointed out that a significant relationship between taxonomic affinity and the origin of plant species does exist. Certain families contain more exotic species than others, thus, taxonomic affinity could be used as an effective indicator in identifying and predicting potentially invasive species in the future. Information on the native origin of species can also serve this purpose. Although this research was very narrow in its scope, it could provide a solid basis for further study on agricultural, ecological, aquacultural, conservational, and commercial effects of exotic plants in this area. Identifying potentially harmful species presents a major challenge for scientists and is an essential step in preventing invasion from exotic plants. Further research is needed to determine if any of these species could present any danger to local ecosystems. Additional statistical analyses should also be performed to determine the probability that any of these exotic plants are harmful. At the same time, increasing society’s awareness of biological invasion should be treated as one of the most important elements in the management and conservation of our native ecosystems. Mack, R.N., Simberloff, D., Lonsdale, W.M., Evans, H., Clout, M. and Bazzaz, F.A. 2000. Biotic invasions: causes, epidemiology, global consequences, and control. Ecological Applications 10: 689-710. Pimentel, D., Lach, L., Zuniga, R., and Morrison, D. 2000. Environmental and economic costs of nonindigenous species in the United States. BioScience 50: 53-65. Pysek, P., Richardson, D.M., Rejmanek, M., Grady, L., Webster, L. and Williamson, M. 2004. Alien plants in checklists and floras: toward better communication between taxonomists and ecologists. Taxon 53(1):131-143. Reichard S H. and White P. 2001. Horticulture as a pathway of invasive plant introductions in the United States. Bioscience 51(2): 103-113. Williamson, M.H.1996. Biological Invasions. Chapman and Hall, London. References Baskin, Y. 2002. A Plague of Rate and Rubbervines: The Growing Threat of Species Invasion. Island Press. Washington, DC. D’Antonio, C.M. and Vitousek, P.M.1992. Biological invasions by exotic grasses, the grass/fire cycle and global change. Annual Review of Ecology and Systematics 23:63-87. KY – EPPC, 2000. Invasive exotic plant list. http://www.se-eppc. org/ky/list.htm 19