Ecohydrological, climatic and tree architectural considerations for reforestation program using swamp vegetation of Bangladesh

Abstract

Swamp forests are now at the edge of extinction in the Haor (Haor ecosystem is a type of wetland comprised of swamp forest located in the lowlands of the north-eastern part of Bangladesh which is characterized by a bowl or saucer shaped shallow depression) region of Bangladesh. To reverse such a trend, there is an urgent need to start a reforestation program. However, the silvics of individual species and dynamics of swamp forest stands are only marginally understood. Hence, the purpose of this study was to provide detailed information on swamp vegetation water tolerance range and to identify suitable habitat range for species that are dominant in the reforestation program. It was found that high water-tolerant species can tolerate waterlogging conditions for an average of 13 weeks, followed by 07 weeks by medium water-tolerant species and 02 weeks by low water-tolerant species. In the case of species water depth tolerance, the high water-tolerant group can tolerate an average of 4ft water followed by 2.5 ft water by medium and 1ft by low water tolerant group. Hijol (Barringtonia acutangula), Koroch (Pongamia pinnata), Pitali (Trewia nudiflora) and Borun (Crataeva magna) were the dominant species used for existing small scale reforestation programs. There are no significant differences in resistance against water flow among Hijol, Koroch, Pitali and Borun regardless of vegetation density and water depth. For future large-scale plantations, the machine learning model shows that more than 50% of Haor area is suitable for plantations by these four species. The information generated through this study can be beneficial to planners and managers to aid in developing plantation plans and the design of habitat restoration and enhancement efforts.