Alien plants and wetland biotic dysfunction

The impact of alien plants on wetlands has been recognized for some time, with the displacement of native species and subsequent changes in the nutrient and energy dynamics of the wetlands. In many instances the importance of alien species was not widely recognized until it was too late and the plants had spread and invaded large areas, with Elodea canadensis being an example from the nineteenth century and Spartina alterniflora more recently. The reasons for this included: (i) a generally low level of public and institutional awareness of the problems; (ii) insufficient information about alien species and ways of controlling them; or (iii) insufficient capacity to collect information or implement control measures. The extent of wetland dysfunction caused by alien plants is now more recognized, but prevention and control can still prove difficult.