AN ADAPTIVE MANAGEMENT APPROCAH TO CONTROL SPREAD OF INVASIVE ALIEN SPECIES IN BUNDALA RAMSAR WETLAND IN SRI LANKA

Abstract

Habitat degradation due to invasive plant species is identified as one of themajor threats in several protected areas managed by Department of WildlifeConservation in Sri Lanka. Bundala National Park, covering an area of 6216ha is located about 250 km Southeast of Colombo (06°08' - 06°14' N, 81°08'- 81°18'). The Bundala National Park is Sri Lanka's first Wetland ofInternational importance declared under the Ramsar Convention. The parkconsists of mainly dry thorny scrubland and lagoons, which are shallowbrackish water lagoons. They harbours a rich bird life including severalspecies of migratory waterfowls. It also contains key nesting sites for fivespecies of marine turtles. Arid and semiarid terrestrial habitats shelter a widerange of species, including elephants and other mammals, reptiles,amphibians and fish species. The introduced Prosopis julifolia, a tree speciesnative to Central and South America as a fuel wood in home gardens by theForest Department has expanded its distribution and has invaded the BundalaNational Park. There are large stands of Prosopis julifolia that prevents thegrowth of other indigenous species. Furthermore it invades the lagoon and asa result the area covered by the lagoon is also being reduced. Opuntia strictavar. dillenii, which is also a plant native to Central America, is used mainlyas a hedge species around human dwellings and from there it may haveinvaded wetland habitats in Bundala National Park.

The spread of these invasive alien plant species has resulted in theprogressive deterioration of wildlife habitats and native biodiversity in thepark, and hence warranting immediate management to curtail their spread.The general methodology adopted for the invasive plant managementprogramme in Sri Lanka is based on adaptive management techniques.Adaptive management is a process that involves planning, management andmonitoring to provide a framework for testing assumptions, adaptation andlearning. Invasive species were eradicated manually and mechanically. Lackof a planned systematic research programme to compile field observations inareas subjected to invasive plant management is a major constraint. Inaddition, views of non-scientific public and lack of funds for adaptivemanagement techniques are the major constraints