M. A. M. Chowdhury , M. K. Huda , A. S. M. T. Islam

Abstract

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.

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M. K. Huda , A. S. M. T. Islam , M. A. M. Chowdhury

Abstract

Natural regeneration and stand composition of regenerated Garjan (Dipterocarpus turbinatus Gaertn.) seedlings were studied in three sites on 4 seasons at Dulahazara Garjan forest of Cox's Bazar Forest Division during September 1994 to July 1995. Soil samples were collected from 9 stands in three sites Dulahazara Garjan forest during April 1995. Some physicochemical properties such as soil moisture content, P^H, texture, electrical conductivity, cation exchange capacity, total nitrogen, available nutrients such as phosphorus, potassium, calcium, sodium, magnesium, manganese and iron were determined. Soils were found to be moderately fertile. The average number of regenerated seedlings appeared to be approximately 8713, 7037 and 7483 ha¹ in site S₁, Site-S₂ and Site-S₃ respectively. Whilst the number of regenerated seedlings appeared to be 8981, 7868, 6265 and 7867 ha^-1 on late monsoon, winter, early monsoon and monsoon respectively. The variation in number of seedlings was remarkable with seasons compared to those in sites. None of the physico-chemical properties of soil did have any significant effect on the distribution of regenerated seedlings except that of Fe which showed a negative significant effect on the distribution of seedlings. The present study suggests that the stand composition of Garjan seedlings irrespective to site conditions of Dulahazara Garjan forest still claims to be potential enough to regenerate naturally in particular.

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