Tham khảo tài liệu 'wetland plants: biology and ecology - chapter 8', khoa học tự nhiên, công nghệ môi trường phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 8 Invasive Plants in Wetlands I. Characterization of Invasive Plants Wetlands and other water bodies around the world have been drastically altered by invasive species. Wetlands with strictly native vegetation are increasingly rare Bazzaz 1986 Meffe and Carroll 1994 Cronk and Fuller 1995 Zedler and Rea 1998 . Wetland invasives directly affect humans by obstructing water flow reducing the recreational value of waters lower accessibility decreased fish production clogged boat motors increased habitat for hosts of parasitic diseases and blocking hydroelectric and other installations Van Zon 1977 . Before we can begin our discussion of invasive plants in wetlands it is necessary to define some of the common terms used in this field. Terms used to describe plants that were historically absent from an area include exotic non-indigenous alien adventive immigrant and non-native Luken 1994 all of which are roughly synonymous. We have chosen to use the term exotic throughout this chapter. The opposite category of plants . those that originated in an area are called native or indigenous. We use the term native in this chapter. Since species are naturally in flux and their distributions shift with time or disturbance their status as native or exotic can be difficult to establish. Evidence from fossil and historical records and results from genetic studies are used to determine the origins of plants. Choosing a date or period after which newly arrived plants are considered exotic is problematic. Should we choose the last glaciation as a cutoff date The introduction of agriculture Post-colonial settlement Schwartz 1997 . In this chapter the plants we describe as exotic have been established as such by many others before us. The focus of our chapter is invasive plants which may be either native or exotic. Invasive plants grow in profusion and produce a significant change in terms of community composition or ecosystem processes. They grow in agricultural or natural areas we are
