Invasive species have been characterized as a “catastrophic wildfire in slow motion” (USDA, 2004). Global trade and transportation have significantly increased the opportunities for insects, plants, diseases, and other invasive species to cross geographic boundaries. Invasive species are not new but the problems they cause are expanding rapidly because of an increased variety of nonnative species and many new types of infestation pathways.
Natural controlling processes and limiting factors that kept species in check in their native ecosystems are not present in their new homes enabling them to thrive. Invasive species can out-compete native species, especially when ecosystem health is stressed by factors such as drought, fire, pollution, resource overutilization, or other disturbances.
A species is considered invasive if it meets these two criteria:
- It is nonnative to the ecosystem under consideration, and
- Its introduction causes or is likely to cause economic or environmental harm or harm to human health.
This definition is derived from Executive Order 13112 issued on February 3, 1999 (USDA, 2004).
Take China as a case study, a wide range of habitats and environmental conditions makes China especially vulnerable to the establishment of invasive species of foreign origin. Potential invasive alien species from most areas of the world may find suitable habitats somewhere in China.
China has a long history of introduction of non-native species, especially species proven to be productive elsewhere and offering potential economic benefits to China. Early introductions were associated with immigration and trade among different regions, such as, during the Han Dynasty, a “Silk Road” connected the Weihe River in northwestern China, via countries in central Asia, with eastern Turkey– brought back seeds of economic plants to China from central Asia, including grapevine (Vitis vinifera), alfalfa (Medicago sativa), common pomegranate (Punica granatum), and safflower (Carthamus tinctorius). All except grapevine have escaped to the wild in western China.
Currently, its rapid economic development, including an explosive growth in international trade and transportation, has increased the potential for introduction of non-native species. Thus, alien species are widespread in the country, occur in many ecosystems, represent most major taxonomic groups, and are introduced unintentionally as well as intentionally for cultivation. In view of the ecogeographic similarities between the United States and China, the US situation may be a bellwether of future trends in China as China’s world trade and domestic development continue to expand.
View the following video lectures:
3.2.1 Basic introduction on international important forest pests
3.2.2 General situation of forestry invasive species in the world
3.2.3 Serious invasion of alien species
3.2.4 How to manage invasive species?
- Invasive Species. (2015). Retrieved January 22, 2015, from http://en.wikipedia.org/wiki/Invasive_species
This article explains causes, ecology, and effects of invasive species.
- Xie, Y.,Li, Z.Y.,William, P. G., & Li. D. M. (2001). Invasive species in China – an overview. Biodiversity and Conservation, 10, 1317–1341. Retrieved from http://www.planta.cn/forum/files_planta/1_invasive_species_in_china_an_overview_2001_716.pdf
The paper lists various cases of invasive species which have caused significant threats or damages to local natural or artiﬁcial ecosystems, and indicates that two example industries (fresh water ﬁsheries and lawn grasses) have brought or tend to bring in many invasive species and hence have caused or will cause changes and loss of biodiversity in local ecosystems. Based on these studies, it is suggested that China combat the problem through enhancing awareness, development of a database on invasive species, strengthening international co-operation, preparing case studies and introducing the necessary legislation, regulations and monitoring.
- S. Department of Agriculture Forest Service. (2004, October). National strategy and implementation plan for invasive species management. Retrieved from http://www.fs.fed.us/invasivespecies/documents/Final_National_Strategy_100804.pdf
This plan was designed by the Chief of the U.S. Department of Agriculture Forest Service, which identified a strategic direction for Forest Service programs spanning Research and Development, International Programs, State and Private Forestry, and the National Forest System. To that end, a multidisciplinary team of specialists, managers, and researchers developed this National Strategy and Implementation Plan for Invasive Species Management (national strategy).
- Global Invasive Species Programme (GISP). (2009). List of invasive alien species (IAS) online information systems [Database]. Retrieved from http://www.issg.org/database/reference/index.asp
This document contains a list of Internet-accessible databases and information systems providing species, bibliographic, taxonomic, expertise, distributions, images and many other information types as they pertain to invasive, exotic, alien, introduced, non-native species and all other species of world flora and fauna.
- Simberloff, D. (2013). Invasive species: What everyone needs to know? New York, NY: Oxford University Press USA. ISBN: 9780199922031
This book offers a wide-ranging and informative survey that sheds light on virtually every aspect of some famous biological invaders. Filled with case studies of an astonishing array of invasive species, the book covers such topics as: how humans introduce these species-sometimes inadvertently, but often deliberately; the areas that have suffered the most biological invasions; the methods we use to keep our borders safe; the policies we currently have in place to manage these species; and future prospects for controlling their spread. The author analyzes the direct and indirect impacts of invasive species on various ecosystems, such as when non-native species out-compete native species for food or light, describes how invasive species (such as the Asian mosquito that is a vector for West Nile virus, itself an invasive species) transmit pathogens, and explains his acclaimed theory of “invasional meltdown” in which two or more introduced species combine to produce a far more devastating impact than any one of them would have caused alone. The book also discusses the more controversial issues surrounding invasive species. It concludes with suggested readings and a list of related web sites.
Self-test for Topic 2
- What is the difference between invasive species and native species?
- List some important invasive species for your homeland.
- Which invasive species has an impact on your life?
- Pick one invasive species and discuss how you would control it.
- How would you prevent species invasion in customs?
- How can species invasion affect international trade?
After formulating your answers, you may post them online at the Knowledge Café for this course as a way to share your ideas and glean knowledge from other students’ responses.