Abstract
Jagot Chand Malaker The phytosociological and ethnobotanical studies were carried out in the selected areas of Madhupur sal forest (MSF) of Tangail district from February 2006 to March 2007 and Lawachara forest (LF) of Maulvi Bazar district from April 2007 to May 2008 to investigate the community structure, species composition and species diversity. Hundred circular plots each of 300m2 area in MSF and 50 plots in LF were studied. In MSF, 174 plant species was recorded under 131 genera and 54 families. About 102, 17, 34 and 21 species were classified as under tree, shrub, herb and climber respectively. As regards to diversity of species by genera, Ficus was the largest genus having 10 species followed by Dioscorea and Syzygium with 4 species each. The genera Terminalia, Acacia, Albizia, Bauhinia, Artocarpus and Calamus contained 3 species each. Some 106 genera were found containing only one species each. Among 54 families, Leguminosae was the largest having 15 genera with 24 species followed by Euphorbiaceae containing 8 genera with 9 species and Apocynaceae with 6 genera and 6 species. The family Combretaceae, Cyperaceae, Ebnaceae, Lauraceae, Lythraceae, Palmae and Rhamnaceae were represented by single genus with multiple species each and some 14 families had only single species each. In LF, 159 plant species were recorded under 123 genera and 60 families. Among the species, 78, 14, 42 and 25 species were under tree, shrub, herb and climber respectively. As regards to Ficus and Syzygium were the largest genera having 7 each species followed by Terminalia and Dioscorea with 4 species each while Artocarpus, Calamus, Piper, Alpinia and Curcuma having 3 species each. Some 106 genera were recorded with only single species each. Among 60 families, Leguminosae was the largest family having 12 genera with 13 species followed by Compositae containing 7 genera with 7 species. The family Euphorbiaceae and Gramineae had 6 genera and 6 species each followed by Anacardiacea, Apocynaceae and Rubiaceae with 5 genera and 5 species while, Verbenaceae containing 5 genera with 6 species. Combretaceae, Cyperaceae, Dioscoreaceae, Guttiferae, Musaceae, Myrtaceae and Piperaceae were represented by single genus with multiple species and some 30 families with only single species each. In case of tree species in MSF, Shorea robusta showed the highest IVI (54.51), Species diversity-H (0.1568), TBC (93.78 m2/ha), EC (173.76) and Cd (0.195). In LF, the highest IVI (30.17), H (0.1352), TBC (109.75 m2/ha), species EC (36.28) and Cd (0.0338) were observed in Artocarpus chama. In case of tree sapling in MSF, Shorea robusta showed the highest IVI (71.47), H (0.149), TBC (4.93 m2/ha), EC (117.60) and Cd (0.000058). In LF, the highest IVI (32.10), H (0.1251), TBC (1.40) m2/ha), EC (28.55) and Cd (0.0237) were observed in sapling of Artocarpus chama. The highest seedling density in MSF and LF was found with Shorea robusta (2580.14 plants/ha) and Artocarpus chama (1007.58 plants/ha) respectively. In case of herb, Axonopus compressus showed the highest density (310000 and 205000 plants/ha), frequency (60 and 100%), abundance (516666.67 and 205000 plants/ha) and A/F ratio (8611.11 and 2050) in MSF and LF respectively. In case of shrub, Clerodendrum infortunatum showed the highest density (3250 and 1250 plants/ha), and frequency (100 and 80%), abundance (3250 and 1562 plants/ha) in MSF and LF respectively. The maximum A/F ratio was 50.00 and 34.00 with Mimosa pudica and Ageratum conyzoiode in MSF and LF respectively. Among climbers Mikania cordata showed the maximum density (416.67 plans/ha), abundance (694.44 plants/ha) and A/F ratio (11.57) with in MSF while, Calamus guruba showed the highest density (600.00 plants/ha), abundance (857.15 plants/ha) and A/F ratio (12.25) in LF. The species Ichnocarpus frutescens had the highest frequency rate (100%) in both the forests. The Sorensen index / beta diversity of both the forests was 0.593 indicating 59.3% similarity. Ethnobotanical studies revealed indigenous people use the forest resources mostly in eleven different categories of practices. About 110 medicinal plants were used by the Garo and 53 medicinal plants were used by the Khasia and Tripura communities for human health care system in both the forests. A number of threats to plant species and their habitats in both the forests have also been identified, which are on the verge of extinction, demanding proper conservation measures to be taken.