SPECIES DIVERSITY AND PHYTO-CLIMATIC GRADIENT OF A MONTANE ECOSYSTEM IN THE KARAKORUM RANGE

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 Km y. 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.