Songklanakarin Journal of Science and Technology SJST-2016-0103.R1 Jamtsho The species composition of the vegetation along the Sherichhu River, lower montane area of Eastern Bhutan Journal:For Songklanakarin Review Journal of Science Only and Technology Manuscript ID SJST-2016-0103.R1 Manuscript Type: Original Article Date Submitted by the Author: 22-May-2016 Complete List of Authors: Jamtsho, Tenzin; Prince of Songkla University, Biology; Yadi Higher Secondary School, Science Sridith, Kitichate; Prince of Songkla University, Biology; Prince of Songkla University, Biology Sherichhu River, Bhutan, riparian vegetation, species composition, litter Keyword: thickness For Proof Read only Songklanakarin Journal of Science and Technology SJST-2016-0103.R1 Jamtsho Page 4 of 33 1 2 3 The species composition of the vegetation along the Sherichhu River, lower montane area 4 5 6 of Eastern Bhutan 7 8 Tenzin Jamtso 1* and Kitichate Sridith 1 9 10 11 Department of Biology, Faculty of Science 12 13 Prince of Songkla University, Hat Yai, Thailand 14 15 *Corresponding author: [email protected] 16 17 18 For Review Only 19 20 Abstract 21 22 An investigation of the riparian vegetation along the Sherichhu River, lower montane area of 23 24 25 Eastern Bhutan was conducted from April to December, 2015 to explore the plant communities 26 27 in terms of the species composition. A total number of 18 plots were placed within the remnant 28 29 patches of the vegetation on either side of the river. In total, 172 species of vascular plant has 30 31 32 been recorded. The cluster analysis suggested four types of plant communities in the study area 33 34 viz., th e Mallotus-Desmodium-Rhus shrubland and th e Syzygium venosum woodland 35 36 37 communities which are located in V-shaped valley and the Albizia-Flueggea woodland and 38 39 Quercus glauca woodland communities located in U-shaped valley. In broad-spectrum, the 40 41 topographic features and environmental variables i.e. litter accumulation and flooding condition 42 43 44 might have some impact on the species composition of the plant communities in this vegetation. 45 46 Key words : Sherichhu River, Bhutan, riparian vegetation, species composition, litter thickness 47 48 49 50 51 Introduction 52 53 Bhutan is positioned within the fledgling mountain range of the EasterHimalayas with an 54 55 area of 38,394 km 2. The country is gifted with rich natural resources and plant diversity. About 56 57 58 59 60 For Proof Read only Page 5 of 33 Songklanakarin Journal of Science and Technology SJST-2016-0103.R1 Jamtsho 1 2 3 72.5% of physiological area in Bhutan is covered by forest including shrubs with an altitudinal 4 5 6 gradient from 150 to 7500 masl (Roder et al., 2002). The forests in Bhutan are classified into 7 8 three broad and distinct eco-floristic zones; alpine forests (above 4000 masl), temperate forests 9 10 11 (2000-4000 masl) and sub-tropical forests (500-2000 masl) (Oshawa et al., 1987). The broad- 12 13 leaved forest is the most widespread forest type, accounting for 62 percent of forested area which 14 15 are very rich in species of both sub-tropical and temperate genera (Roder and Frei, 2013). In any 16 17 18 case, only few studiesFor are concerned Review about the vegetation Only accounting mainly on the temperate 19 20 and alpine region along the altitudinal gradient of Bhutan (Grieson and Long, 1983; Sargent, 21 22 1985; Ohsawa et al., 1987; Hara, 1991; Wangda and Ohsawa, 2006; Wangchk et al., 2014; 23 24 25 Jamtsho, 2015). 26 27 With the landscape of Bhutan being characterized by rugged mountains separated by 28 29 river valleys, several type of riparian vegetation are present along the valleys of different areas 30 31 32 from the subtropical ones through the temperate ones, then up to an exclusively alpine region. 33 34 This riparian vegetation has accommodated various numbers of plants as well as wildlife. 35 36 37 Moreover, many of the ancient routes of trade and communication in this region of the 38 39 Himalayan areas were taking place here as one could recognized by the archeological relics e.g. 40 41 old pagoda (the “Chorten” in Dzongkha) which often found along the stream of the remote areas 42 43 44 in Bhutan . In any case, the lack of sufficient literature, as many of the researchers had not paid 45 46 consideration on such type of the vegetation. 47 48 The present study was conducted in order to describe the vegetation composition, plant 49 50 51 communities of the unexplored riparian vegetation of the Lower Montane areas of eastern 52 53 Bhutan Himalaya as an important basic database to support not only the sustainable use of the 54 55 56 57 58 59 60 For Proof Read only Songklanakarin Journal of Science and Technology SJST-2016-0103.R1 Jamtsho Page 6 of 33 1 2 3 plant resources of the Himalaya in future, but also to provide a fundamental information of this 4 5 6 rare habitat of the Himalayan areas in general. 7 8 9 10 11 Methods 12 13 Study area 14 15 The study was conducted along the “Sherichhu River” (27°15’-27°21’N/ 91°24’- 16 17 18 91°24’E), located in MongarFor district, Review Eastern Bhutan (Figure Only 1). The forest along the Sherichhu 19 20 River was selected as the representative for the present study due to its variability including non- 21 22 disturbed vs. disturbed situation as well as its most easily accessible and least risky among all the 23 24 25 rivers surveyed in eastern Bhutan. The upper half of the study area is positioned in Bomdeling 26 27 wild life sanctuary, which is ranging from the lower broadleaved forests to the alpine ecosystem, 28 29 while the lower half of the river is not included in the protected area, therefore, some 30 31 32 anthropogenic influences from animal grazing and looping occurred occasionally. The study area 33 34 is ca. 15 km in length, ranging from 540 to 1450 masl. The climate of the area is humid 35 36 37 subtropical monsoon with mean temperature of 20°C. The annual rainfall is 1200-1500 mm with 38 39 the heaviest rainfall in July (National statistics Bureau, 2014). 40 41 42 43 44 The landscape and study plots 45 46 The landscape of surrounding vegetation was characterized by sharp ridges, high hills 47 48 and narrow valley where meandering river had created narrow flood plain and levees in the 49 50 51 different location. There was prominent deposition of the slit, pebbles, cobbles and the huge 52 53 rocks of varying size along either side of the river having riparian vegetation. The topography 54 55 has supported different plant habitats, viz., woodland, shrubland, open ground and transitional 56 57 58 59 60 For Proof Read only Page 7 of 33 Songklanakarin Journal of Science and Technology SJST-2016-0103.R1 Jamtsho 1 2 3 vegetation between aquatic and terrestrial habitats. Eighteen study plots (size 15 m x 25 m) were 4 5 6 designated in accordance with the Braun-Branquet approach (Kent and Coker, 1994) within the 7 8 remnant patches of the vegetation on either side of the river which was assumed as representative 9 10 11 of riparian plant community. The patches were distinct in floristic composition and physical 12 13 appearances from the surrounding vegetation. The plots were laid on the accessible locations of 14 15 the vegetation along the river (Figure 1C). However, the study sites were assigned to cover all 16 17 18 the landscape types foundFor along theReview river which would, then,Only characterize the fast flowing river 19 20 of this lower montane areas of the Himalaya i.e. plots 1-8 took place along either site of the 21 22 Sherichhu River where in the sharp valley without any curves or sedimentation plain as it was 23 24 25 called “V-shape” valley in the present study vs. plots 11-18 (Plots 13-18 fall within the BWS) 26 27 took place in the valley with small basin/plain where the river may have twisted and, therefore, 28 29 marked a curve that the sedimentation had occurred as it was called “U-shaped Valley” in the 30 31 32 present study and in such type, and old deposition plain is achieved by the river in the pass could 33 34 be seen above the river basin (Figure 2). In addition, the plots 9-10 were laid on the river bank in 35 36 37 the connective part of the river from such “V-shaped” to “U-shaped” valley (Figure 2). The 38 39 location of the plots was limited right from the edge of the river bank up to 50 m in perpendicular 40 41 line with the edge of the river bank and being laid subjectively (according to Kent and Coker, 42 43 44 1994) in selected places along the length of the selected Sherichhu river, where the relic of 45 46 natural vegetation occurred. 47 48 Data collection 49 50 51 The plant surveys as well as selected environmental parameter i.e. altitude, slope, aspect 52 53 and litter thickness were carried out from April to December 2015 to ensure full coverage of the 54 55 flowering season. Altitude was measured using global positioning system, aspect was measured 56 57 58 59 60 For Proof Read only Songklanakarin Journal of Science and Technology SJST-2016-0103.R1 Jamtsho Page 8 of 33 1 2 3 using Suntos compass, slope was measured using Suntos clinometer and litter thickness by ruler 4 5 6 (Zhang et al., 2006, 2013).