Pak. J. Bot., 49(SI): 89-98, 2017. SPECIES DIVERSITY AND PHYTO-CLIMATIC GRADIENT OF A MONTANE ECOSYSTEM IN THE KARAKORUM RANGE ZAHEER ABBAS1, SHUJA UL MULK KHAN2*, JAN ALAM1, ZAHID ULLAH3, SHER WALI KHAN4 AND NAVEED ALAM5 1Department of Botany, Hazara University Mansehra, Pakistan 2Department of Plant Sciences, Quaid-i-Azam University Islamabad, Pakistan 3Centre for Plant Sciences and Biodiversity University of Swat, Pakistan 4Department of Biological Sciences, Karakoram International University Gilgit-Baltistan, Pakistan 5Institute of Agriculture Sciences and Forestry, University of Swat, Pakistan *Corresponding author’s email: [email protected] & [email protected] Abstract Analyzing species diversity and understanding phyto-climatic gradient is crucial for proper management of montane ecosystem. The study site is located in the Karakoram Mountains, Baltistan (Northern Pakistan), covering an area of 2750 Km². It is situated on the right bank of the River Indus in the Central Karakorum Mountains at an elevation range of 2000 to 6000 m at sea level. On the basis of change in topography, elevation and climate study area was classified into four Vegetation Zones viz. dry zone, agro-forestry zone, Sub-alpine zone and Alpine zone. A total of 180 species of vascular plants representing 139 genera and 53 families were collected with generic index of 1.2. Twenty four families were represented by single species. and family Asteraceae was dominant family including 36 species followed by families Papilionaceae, Polygonaceae, Rosaceaeand Chenopodiaceae representative of 11, 10, 10 and 8 species respectively. Artemisia (7 species), Chenopodium (4), Astragalus (4) and Geranium (3) were identified as leading genera. Habit wise perennial herbs prevailed with 113 species followed by annuals (41 species), shrubs (18), biennials (3) and trees (3).In biological spectrum, the area is dominated by 46% of Hemicryptophytes (84 species) followed by 21% therophytes (39), 11% Chamaephytes (21), 10% Nanophanerophytes (18),10% Geophytes (14) and 2% Mega-phanerophytes (3). The altitudinal gradient of species showed that the species richness declines with increase in elevation from sea level. Most of the species found in the middle elevations (2700-3300m) and a sharp decrease were observed at high elevation (above 3900m). Agricultural encroachment, grazing, blasts for gemstones; rock drifting and land sliding were common and severe natural and anthropogenic threats. These and many other threats to the available vegetation urge for more precise botanical explorations and prompt conservatory management in the scenario of national and global interest in these fragile ecosystems. Key words: Vegetation, Diversity, Phytoclimatic gradient, Conservation, Baltistan, Karakorum Mountains Introduction on the earth surface stretching at about 500 Km in the North of greater Himalayas. A part of the Karakorum Vegetation zonation on the basis of elevation is one of mountains is situated in the region of Gilgit-Baltistan of the most remarkable patterns of vegetation and much of the Northern Pakistan and is known as central Karakorum data is available on it at local scales all around the globe range where it follows the right bank of the River Indus and (Grytnes, 2003; Webster, 1961). Vertical zonation into River Shyokin Baltistan, a botanically under explored altitudinal belts with distinct climate is a characteristic region of Pakistan (Ali, 2008). Karakoram possesses dry feature of high mountains (Becker et al., 2007). This topic summer climate. This mountain belt frame inner mountain always remained the focus of interest among the basins, plateau and valley bottoms as desert-like researchers and various studies could be found in different responsible for the typical landscape of the Northern Areas mountain system of the world for instance (Beals, 1969; of Pakistan (Kreutzmann, 2006). It encompasses dozens of Grytnes, 2003; Khan et al., 2011; Mahdavi et al., 2013; deeply incised valleys which exhibit subtropical steppe Ohsawa, 1984). Environmental conditions and vegetation among these high mountain ranges. Dry and semi-dry eco- change rapidly at mountainous ecosystems over short region of the Karakorum is not so rich in floristic distances and consequently these ecosystems attained a composition but give a unique species assemblage with sharply demarcated ecological gradient and vegetation respect to elevation and topography (Dickoré, 1995). zones (Friend et al., 1989; Lomolino, 2001; Odland, 2009). According to (Seong et al., 2007) in the Central The knowledge of the floristic composition of an area is a Karakoram, elevation effects on precipitation results in an prerequisite for any ecological and phyto-geographical altitudinal zonation of vegetation (Khan et al., 2017; Khan studies and conservation management activities (Jafari & et al., 2012). Mountain ecosystems are the remarkable Akhani, 2008). Species richness is the simple and easily landforms on the earth surface distinguished with interpretable indicator of biological diversity (Chesson, prominent vegetation zone mainly based on altitudinal and 2000; Peet, 1974). climatic variation (Khan et al., 2013b; Khan et al., 2016). The Karakorum Range of mountains(71° - 79° E, 35°- The concept of life-forms of vascular plants dates back 36° N) is one of the diverse habitats in the world and to Von Humboldt (1806) that was originally developed for floristically situated at the junction of the Western and a non-taxonomical comparison of vegetation types in Central Asiatic sub-regions of Tethyan Floristic Region different regions of the globe. Various literature ca be (Takhtajan, 1986). It is one the majestic mountain systems found in this aspect for instance (Qadir & Shetvy, 1986; 90 ZAHEER ABBAS ET AL., Tareen & Qadir, 1993; Pavón et al., 2000; Klimes, 2003; elevation. Lower terrain has boulders and screes. Middle Mahdavi et al., 2013). Life forms in an ecosystem indicate elevations encompass enormous arable fields and terraces the adaptations of plant species to the surrounding climate covered with dry northern and southern mountain slopes. (Bano et al., 2017; Khan et al., 2013a). Life-form spectrum Sub alpine has considerable plains on river banks where gives basic climatic information (Campbell & Werger, mono-cropic agriculture is in practice (Abbas et al., 2016). 1988; Danin & Orshan, 1990). It has been repeatedly Winter is prolonged, harsh and cold with plenty of shown that life-form spectra (proportion of species snowfall (Abbas et al., 2016) . The lower areas exhibit hot belonging to individual life- forms) can be predicted for and dry desert sort of environment but at higher elevations particular climatic properties, for any continent, frequent precipitation give rise to richer vegetation. Exact biogeographic region and an ecosystem (Sarmiento & metrological data is not available due to absence of weather station in the area. However, data from Skardu town, Monasterio, 1983). The present study was aimed to situated at a distance of 55 km from the study area showed investigate phyto-climatic gradient and develop vegetation h i i - zones in the studied region for better management and C), a i C) from November to conservation of floristic diversity. March (K i š & Dick é ). Floristically, it falls in Eastern Irano-Turanian sub region (Ali & Qaiser, 1986). Materials and Methods Study area: The study area Shighar Valley covers an area Data Collection: Field trips were arranged to the study of approximately 2750 Km2 in the District Skardu in area in the summer of 2011 for a period of seven months. Baltistan region (Northern Areas, Pakistan) (Fig.1) (Abbas Plant specimens were collected at different elevations and et al., 2016). It is situated on the right bank of the River various seasons. Qualitative attributes like species Indus in the central Karakorum Mountains with elevation composition, diversity and phenology were assessed. The limits between 2000-6000m asl. It borders with a small quantitative ecological techniques were found out using valley Homarah in the East, Thowar in the west and the quadrat method. Sizes of the quadrats used for tree, shrub River Indus in the South. Kathio, Matumbur, Chongchan and herb species were 10 × 10 m2, 5 × 5 m2 and 1 × 1 m2 and Niarmo are well-known glaciers. Tributaries from respectively (Ahmad et al., 2016; Khan et al., 2016a; Khan these glaciers shape the valley main water course is an et al., 2016b). All plant species were classified into life Indus tributary having numbers of settlements on its banks. form categories using Raunkiaer classification (Khan et al., Chabrunmo (Chutron) lake a hot spring while Baa-rzing (seasonal), Khla-rzing and Naqpo-rzingbu are permanent 2016c; Raunkiaer, 1934). The plant specimens were high altitude lakes in the valley. collected and identified through nomenclature mainly Physiographically, two parallel sub mountain systems based on Flora of Pakistan and other literature (Nasir & give zigzag shape to the valleys and it arise abruptly by stony Ali, 1968-1988; Ali & Nasir, 1989-1992; Ali & Qaiser belt in lower most area giving a diverse topography along the 1993-Todate). Fig 1 Map of the study area PHYTO-CLIMATIC GRADIENT AND KARAKORUM MOUNTAINS 91 Results potentilla anserine, Rumax spp, Silene vulgaris, Trifolium spp and Taraxacum spp are commonly distributed. Vegetation Zonation: As the study area exhibits varied Hippophe rhamnoides Myricaria germanica ssp. physical geography, climatic conditions and hence diverse pakistanica and Tamaricaria