Assessment of Soil Physicochemical Properties along an Altitude Gradient in High Altitude Region of Gangotri National Park, Uttarakhand, India Priyanka Kashyap 1* , Anjum Nasreen Rizvi 2 and V. P. Uniyal 1 1 Wildlife Institute of India, Chandrabani, Dehradun – 248001, Uttarakhand, India; 11priyankakashyap@gmail.com 2 Zoological Survey of India, New Alipore, Kolkata – 700053, West Bengal, India Abstract The present study was undertaken in the sub-alpine and alpine region of Gangotri valley of Gangotri National Park (GNP) in the Uttarkashi district of Uttarakhand, India. Results showed that selected soils were sandy loam (83%) throughout the region. Soil reactions (pH) vary from 5.00 – 6.28 and showed acidic to the slightly neutral condition. The mean soil Nitrogen (N), and Phosphorus (P) content were calculated 0.37 ± 0.02% and 0.35 ± 0.02%. The value of NP first increased and then decreased along the elevation. Nitrogen and Phosphorus values ranged from 0.01-0.73 and 0.13-0.87. The correlation analysis among the different soil parameters showed that Soil Organic Carbon (SOC) was positively correlated with soil moisture(r = 0.661, p = 0.038); Phosphorus (r = 0.794, p = 0.006) and Nitrogen (r = 0.964, p = 0). SOC and soil moisture increases at the middle elevation (3400-3500 m and 3700-3800 m) and further decreases along the elevation. This may be explained as the impact of long term human influence and altering the natural habitat in the form of a camping spot for trekkers at this elevation and presence of mixed forest (subalpine deodar, pine, and birch) at 3400-3500 m elevational range. This baseline information on soil parameters in Gangotri valley may further help in climate change study in the current scenario of global warming in relation with above ground vegetation and underground soil biota to understand the soil food web dynamics. 1. Introduction Te composition of the forest stand and ground cover is infuenced by the forest soil as it is highly afected by the soil Nitrogen content (N), Phosphorus (P), and soil pH 1 . Variation in physiochemical properties of forest soil occurs due to variation in climate, soil fora and fauna activities, weathering processes, topography, vegetation cover and other biotic and abiotic variables. In soil formation, vegetation plays a key role as plants litter from aboveground and root detritus below ground are the major source of Soil Organic Matter (SOM) which infuences the soil properties such as pH, Soil Organic Carbon (SOC), soil texture 2 . Changes in soil properties can be seen with disturbances. Among all nutrient elements availability of soil, Phosphorus is known to afect plant production as more than 80% of the soil Phosphorus gets fxed and become unavailable for plants 4 . In most ecosystems, Nitrogen is considered as a primary limiting micronutrient but in higher altitude alpine and temperate regions availability of Phosphorus may act as a primary limiting element 10 . It has been found that the availability/concentration of Phosphorus in the Indian Himalayan Region (IHR) vegetation is less than the other high altitude forests in the world 17 . Work has been done on soil characteristics and classifcation in various regions of IHR by many workers 3,5,7,8,11,12 . Te literature on soil characterization reveals that data has been documented mainly for the lesser Himalayan region in Himachal Pradesh and *Author for correspondence ©2020 Te Academy of Environmental Biology, India Journal of Ecophysiology and Occupational Health, Vol 20(3&4), DOI: 10.18311/jeoh/2020/26028, 134–139, July–December 2020 ISSN (Print): 0972-4397 ISSN (Online): 0974-0805 Keywords: Elevation Gradient, Gangotri National Park (GNP), High Altitude Soil, Indian Himalayan Region, Physicochemical Properties