AN ANNOTATED CHECKLIST OF THE ANGIOSPERMIC FLORA OF RAJKANDI RESERVE FOREST OF MOULVIBAZAR, BANGLADESH

This study was carried out to provide the baseline data on the composition and distribution of the angiosperms and to assess their current status in Rajkandi Reserve Forest of Moulvibazar, Bangladesh. The study reports a total of 549 angiosperm species belonging to 123 families, 98 (79.67%) of which consisting of 418 species under 316 genera belong to Magnoliopsida (dicotyledons), and the remaining 25 (20.33%) comprising 132 species of 96 genera to Liliopsida (monocotyledons). Rubiaceae with 30 species is recognized as the largest family in Magnoliopsida followed by Euphorbiaceae with 24 and Fabaceae with 22 species; whereas, in Lilliopsida Poaceae with 32 species is found to be the largest family followed by Cyperaceae and Araceae with 17 and 15 species, respectively. Ficus is found to be the largest genus with 12 species followed by Ipomoea, Cyperus and Dioscorea with five species each. Rajkandi Reserve Forest is dominated by the herbs (284 species) followed by trees (130 species), shrubs (125 species), and lianas (10 species). Woodlands are found to be the most common habitat of angiosperms. A total of 387 species growing in this area are found to be economically useful. 25 species listed in Red Data Book of Bangladesh under different threatened categories are found under Lower Risk (LR) category in this study area.


Introduction
Rajkandi Reserve Forest (RRF) is located in Kamalganj upazilla under Moulvibazar district of Bangladesh. This forest area consists of ca. 2,450 hectares' land of Rajkandi forest range that lies between the 24º12´-24º17´N and 91º51´-91º55´E, and comprises diverse habitats and ecosystems. This tropical semi-evergreen forest falls within the Indo-Burma hot-spot of biodiversity (Myers et al., 2000).
The extensive floristic exploration throughout British India conducted by J.D. Hooker (1872Hooker ( -1897 included the Sylhet region of the present political boundary of Bangladesh. Later, David Prain (1903) covered different regions of Bangladesh including Sylhet under his floristic exploration. Kanjilal et al. (1934Kanjilal et al. ( , 1938Kanjilal et al. ( -1940 included some areas of Sylhet region too. In those studies, any specific or detail information on local distribution and voucher specimens of the taxa described are missing. Later on, various sporadic inventories have been completed in different areas of greater Sylhet region, such as Das (1968), Alam (1988), Arefin et al. (2011), Uddin and Hassan (2004) and Sobuj and Rahman (2011). However, the flora and plant diversity of Moulvibazar district, have not yet been explored, except the plant diversity (Uddin and Hassan, 2010) or a plant group (Haque et al., 2016) of a particular area. Taxonomic data on the current floristic composition of RRF collected through field inventories and examination of representative plant specimens are still lacking, though such data are important for the sustainable use and 1 conservation of plant resources and resource-based development of the area. Therefore, an inventory on the floristic composition of RRF was conducted with the objectives to produce an annotated checklist of the angiospermic species of the area; to determine the current status of threatened species of angiosperms from Bangladesh in this forest; and to collect and preserve representative plant specimens for future reference. followed by Ipomoea, Cyperus and Dioscorea with five species each and Maesa, Piper, Senna, Terminalia, Phyllanthus, Mussaenda, Ixora and Bambusa with four species each. The composition and distribution of species in all of the three forest beats of RRF, namely Adampur, Kurma and Kamarchara, were found to be variable remarkebly. A total of 231, 26 and five species were found to occur exclusively in Adampur-, Kamarchara-and Kurma beats, respectively. The occurance of total 538 species in Adampur beat, with 231 species exclusive and additional 307 species overlapping in other two beats (240 in Kurma and Kamarchara, 46 in Kurma and 21 in Kamarchara), indicates that this forest beat could be considered as a hotspot of biodiversity.
In this forest, woodlands were found to be the most common habitats harbouring the highest number of species (157 species), and this might be due to accumulation of nutrient components and humus-rich soil. In contrast, the finding of hill top to harbour relatively lower number of species (16 species) might be due to their poor humus and nutrient components.
The total number of angiosperm species (549) found in Rajkanndi Reserve Forest during this study is 15.20% of the total 3,611 species, and that of angiosperm families (123) is 59.42% of the total 207 families reported for Bangladesh (Ahmed et al., 2008(Ahmed et al., -2009 The study recognizes a total of 387 angiosperm species of RRF as economically useful and among these species 82 are useful in two and 17 in three categories. The major categories of these economically useful species are medicinal (231 species), timber (50 species), fruit (49 species), ornamental (47 species), vegetable (34 species), fodder (23 species), domestic uses (19 species), fuel wood (11 species), and soil binder (9 species).
The RRF area houses 25 species included as threatened in the Red Data Book of Vascular Plants of Bangladesh (Table 1; Ara et al., 2013). This emumeration of threatened species is higher in respect to that reported for few forest areas, e.g., Lawachara National Park (Uddin and Hassan, 2010) and Sundarban Mangrove Forest (Rahman et al., 2016), and on the other hand, lower in respect to that recorded from other forest areas of Bangladesh (e.g., Rema-Kalenga forest; Uddin and Hassan, 2004). All of these 25 species were found in many localities of RRF with normal natural regeneration and any threat or stress exclusive for these species could not be recognized there, and therefore, they were categorized under the Lower Risk (LR) category for Rajkandi Reserve Forest.
This checklist provides basic information on all angiosperm species currently occurring in the Rajkandi Reserve Forest, which can be considered as an important database as well as baseline to track the trend of changes in the floristic composition of this reserve forest in course of time and different biogeographical processes. This study also informs the current status of 25 threatened species in RRF. These data might be useful in planning, management, conservation and sustainable development of this valuable forest resource of Bangladesh.