Study area

The current study was conducted at the Khunjerab National Park (KNP) which is situated in the HKKH (Hindukush-Karakoram-Himalaya) mountain ranges near the border with China (36.37° N, 74.41°E). The KNP is spread over an area of 4455 km² with altitudes ranging from 2439 m to 4878 m above sea level. [41, 42]. The study was established in the alpine zone where the climate is defined by warm summers starting from May till August. The maximum temperature in May recorded in the warm year goes up to 25°C [43] while in winter it drops down below 0°C (up to –10°C) from October at 3346 m [17, 44, 45]. Valleys of KNP are characterized by stony beds, water channels (Nullah), vegetation with grasses, and large plants like bushes along slopes. Khunjerab is covered with grasses and has green pastures. Genus Artemisia and Poa exist here predominantly. The current state of knowledge is based on the analyzed climatic trends in HKKH region from data available from 1980 to 2009 [46], which indicates the rapid declines in the glaciers of the Great Himalaya which attributes to global warming [47]. The reports of the weather station at Gilgit, illustrate the significant increase in mean annual temperature (average 0.65°C) which is higher than the global average (0.17°C) during the last 35 years [48].

The alpine KNP region includes the following vegetation altitudinal zones: 1) The sub nival zone (> 4500 m) is made of snow and bare desert, covering about 30% of the national park area. Characteristic plant species are Saussurea simpsoniana, Primula macrophylla, Oxytropis macrophylla, Potentilla multifida, and Hedinia tibetica [49]. 2) Alpine meadows (3500–4500 m) are rich in herb biomass and therefore serve as an important habitat for livestock (sheep, goats, cattle, and yaks) and wild herbivores such as ibex (Capra ibex sibrica), golden marmot (Marmota caudata aurea) and Marco Polo sheep (Ovis ammon polii). Dominant plant taxa are Primulla macrophylla, Plantago lanceolata, Saxifraga spp., Potentilla hololeuca, Poa alpina, and Carex spp. 3) The sub alpine Steppe (< 3500 m) is vegetated mainly with Artemisia and Primula plant genera. Some grasses such as Poa and Carex spp. are also found in relatively moist places [50].

The summer pastures of KNP are subjected to grazing management systems by indigenous communities because they are rich in herbaceous biomass [5]. In 2013, an analysis conducted to document the changing aspects of above ground biomass (AGB) in high altitude rangelands of Pakistan, proclaimed the number and types of livestock in KNP pastures featuring more than 5000 individuals including sheep, goat cattle yak, and others (horses & donkeys) [51].