Pak. J. Bot., 53(5): DOI: http://dx.doi.org/10.30848/PJB2021-5(43) VEGETATION DYNAMICS ALONG ALTITUDINAL GRADIENTS IN THE SHIGAR VALLEY (CENTRAL KARAKORUM) PAKISTAN: ZONATION, PHYSIOGNOMY, ECOSYSTEM SERVICES AND ENVIRONMENTAL IMPACTS ZAHEER ABBAS 1* , SHUJAUL MULK KHAN 2 , JAN ALAM 3 , THOMAS PEER 4 , ZAINUL ABIDEEN 5 , RAINER W. BUSSMANN 6 AND SAID MUHAMMAD 3 1 Department of Botany, University of Education, Lahore, Pakistan 2 Department of Plant Sciences, Quaid-i-Azam University, Islamabad, Pakistan 3 Department of Botany, Hazara University, Mansehra, Pakistan 4 Department of Organism Biology, University of Salzburg, Salzburg, Austria 5 Dr.Muhammad Ajmal Khan Institute of Sustainable Halophyte Utilization, University of Karachi, Karachi, Pakistan 6 Department of Ethnobotany, Institute of Botany, Ilia State University, Tbilisi, Georgia * Corresponding author’s email: zaheer.abbas@ue.edu.pk, shujaqau@gmail.com Abstract This paper provides the first insight into the altitudinal zonation of vegetation of Shigar valley, Central Karakorum Mountains, Pakistan. The study was conducted in the period of 2013-2016 and focused on floristic and structural differentiation of vegetation; ethnobotany, and environmental impacts in the region. Based on altitude, climate, and indicator species, four vegetation zones were recognized including sub-montane, montane, sub-alpine, and alpine belt. From these belts, a total of 345 plant taxa were collected. The sub-montane belt presented the highest species richness. Perennials prevailed in all vegetation types. Annuals drastically decreased with altitude. Hemicryptophytes occurred in all zones, and chamaephytes only at lower, dry and rocky sites. Phanerophytes (shrubs, trees) decreased with altitude and were almost absent in the alpine belt. Microphylls and nanophylls had an abrupt decline with altitude. Plant functional effects related to ecosystem services were sixteen and the maximum services were found in the sub-alpine (13) belt, followed by the sub-montane (12), the montane (9) and the alpine belt (4). All vegetation types were used by the local people, and twenty use categories with 83 species were found, including medicinal, beverages, edible, fuel, fence sources etc. Edible wild plants (fruits, vegetables), fuel wood, thatching, and fencing materials were provided by all vegetation belts except the alpine belt. The use of plants impaired plant functional effects in the ecosystem. Eight types of natural and human caused degradation processes were recognized, most common in the sub-montane and montane belt. The sustainable use of the resources requires appropriate monitoring activities, and regulation for conservation and management of this vulnerable mountain ecosystem. Key words: Vegetation belts, Plant diversity, Plant adaption, Ecosystem services, Environmental risks. Introduction The scientific interest in altitudinal zonation of vegetation is very old and probably started with the script of Tournefort in 1717 (Clements, 1905). Since that early date, field botanists focused the subject and considerable literature focuses on alpine ecology (Daubenmire, 1943; Beals, 1969; Dickoré, 1991; Dickoré & Nüsser, 2000; Akhani et al., 2013; Abbas et al., 2017b ; Abbas et al., 2021). Mountains cover large parts of the earth and are of remarkable biological diversity (Körner et al., 2011). Mountains are characterized by rapidly changing geophysical features, climate and life zones over a short elevational distances (Körner, 2004). Therefore, altitude is frequently used as potential factor in order to assess vegetation zonation, community types, species diversity, biological spectra, and ecosystem services in the alpine ecosystems (Mani, 1978; Grytnes, 2003; Klimes, 2003; Sharma et al., 2009; Saqib et al., 2011; Zeb et al., 2021; Iqbal et al., 2021). Global climate change, unsustainable land use, deforestation and high grazing pressure were identified as potential challenges in different world mountain ranges (Breckle & Wucherer, 2006; Spehn et al., 2006; Noroozi et al., 2011; Haq et al., 2021). Mountains are hotspots of biological diversity but they are considered especially susceptible to global change due to its steep climatic conditions (Kohler et al., 2010; Körner et al., 2017). This demands to address the potential threats, environmental degradation and human made hazards in order to design conservation plans and sustainable utilization of resources. The Karakorum Mountains are one of the famous ranges in the northern region of Pakistan. Approximately 113000 people live within the zone of Central Karakorum Range and are continuously altering the fragile montane ecosystem for their subsistence. The rapid and severe anthropogenic impacts make vegetational studies very urgent. Such studies are very limited in entire region of Baltistan, particularly in the valleys of Central Karakorum. However, some regional studies on floristic and medicinal plants exist, for instance, Hussain et al., (2011), Bano et al., (2014a), Bano et al., (2014b), Abbas et al., (2016), Abbas et al., (2017a); Abbas et al., (2017b), (Abbas et al., 2017b), and Abbas et al., (2019), but related studies on vegetation ecology and phytosociology are largely absent. The purpose of the present study, however, was to present the vegetation composition, plant adaption and ecosystem services along the altitudinal gradients within the inner alpine Shigar Valley. The research objectives were i) to elucidate how altitude effects vegetation, floristic composition, and plant adaption ii) to evaluate the use of plants by the indigenous population, and iii) how natural and anthropogenic impacts affect local plant biodiversity.