PARENT SESSION
Poster Session: Ecological Impacts of Invasive Plants
Tuesday, November 4, 2003, 5:00 PM to 7:00 PM
Global Ballroom

Ecological impacts of invasive plants in Sunderbans mangroves.

Biswas, Shekhar^*,1, ¹ IUCN - The World Conservation Union, Dhaka, Bangladesh

ABSTRACT- Sunderbans is the worlds largest continuous single block of mangrove forest. Its rich blend of flora, fauna and vivid ecosystem function make it a unique ecosystem in the world. Over the few years the forest is under severe human disturbance. These are basically changed in the salinity regime, introduction of terrestrial species in the mangroves, construction of dams and illicit felling. All these leads introduction of few alien species at the same time several native species to become invasive. Among the exotic species Echhornia crassipes, Eupatorium odoratum, Micania scandens, Syzygium fruticosum are causing enormous damage to the Sunderbans ecosystem. On the other hand, Derris trifoliata, Acrosticum aureum, though known widely as mangrove associates, now affecting the ecosystem badly. Initially these species does not seems problematic but as human disturbance increase, so as their rate of invasion also increase. A study was conducted through a combination of systematic and purposive sampling to identify their impact on the Sunderbans. It was appeared that these species affect the Sunderbans ecosystem from very initial stage of ecosystem dynamics. Echhornia crassipes, Acrosticum aureum impedes the mangrove propagule movement. Eupatorium odoratum, Micania scandens by its bush besides restricting propagule movement also impedes mangroves normal expansion. Derris trifoliata twist the host tree. Syzygium fruticosum initially was limited only within open raised area of Sunderbans but the species has coped to stay with the saline environment and densely colonizes inside the forest floor. In newly formed land these species with their profuse regeneration colonizes and restricts mangrove settlements. The ecological associations of these species were also identified. Monitoring of rate of invasion with abundance was suggested for determination of ecosystem health hazards caused by invasive plants.

Key words: invasive plants, Sunderbans, ecological impact, Derris trifoliata