Phytodiversity of Dipterocarpus turbinatus Gaertn.f. (Garjan) Undergrowths at Dulahazara Garjan forest, Cox's Bazar, Bangladesh

The Phytodiversity of Garjan (Dipterocarpus turbinatus Gaertn.f.) undergrowth was studied on 4 seasons during September 1994 to .July 1995 by random quadrat method at Dulahazara Garjan forest. 85 undergrowth species belonging to 43 families were recorded and classified into 2 Ferns of 2 families, 15 Monoeot species of 8 families, 65 Dieot species of 33 families and the rest 3 species are still unidentified. Maximum number of undergrowth species were found in Leguminosae and Euphorbiaceae of Dicot, and Gramineae and Commelinaceae of Mono cot. Various life forms of the undergrowth such as Epiphytes (1.18%), Megaphanerophytes (18.82%), Microphanerophytes (29.4%), Nannophanerophytes (20%), Hemicryptophytes (7.06%), Chamaephytes (15.29%), Hydrophytes (4.71%), Therophytes (1.18%) and Geophytes (2.35%) were determined and plant climate was termed as Micro-nanno-megaphanerophytes. The undergrowth species were further classified into tree (18), shrub (23), undershrub (6), herb (14), climber (17), grass (3), sedge (2) and fern (2) species. Maximum undergrowth species were recorded during monsoon. The species diversity and diversity index of undergrowth species were calculated following Shannon-Wiener's diversity function (H) and Simpson's diversity index (D) and the result revealed that protected site led with highest values of species diversity. The present study suggests that Garjan plants and assocrated undergrowths are being degraded mainly by leaf-litter fall and wood collection, grazing, firing, soil erosion, unplanned logging etc. which may bring an alarming change in the whole Garjan forest ecosystem as well as the gene pool of existing phytodiversity.