Impact of Anthropogenic Disturbances on Alpine Floristic Diversity along the Altitudinal Gradient of Northwestern Himalayas

Abstract

Vegetation patterns in the high-altitude Himalayas are influenced by a complex set of biotic and abiotic factors. Anthropogenic disturbances are one of the primary factors influencing the community patterns and diversity, which are largely determined by the level of accessibility in the Himalayas. However, with advancing urbanization and accessibility, limited efforts have been made to quantify the impact of road constructions on the alpine flora of the Himalayas. To overcome this data gap, this study aimed to quantify the impact of anthropogenic disturbance on the alpine vegetation community pattern along the altitudinal gradient, i.e., 3264–4340 m in Kullu district and 3148–4634 m in Lahaul and Spiti district of Himachal Pradesh, Northwestern Himalayas. The impact of anthropogenic disturbance was assessed by comparing species diversity and richness between selected disturbed and undisturbed sites. The diversity profiles of disturbed sites (2.45), near roads and highways (within 25–50 m), were indicative of a higher level of anthropogenic disturbances than undisturbed sites (2.56), which were located at a farther distance (more than 25–50 m) from roads and highways. The variation in diversity profiles of disturbed and undisturbed sites was further favored by lower values of soil moisture, potassium, phosphorous, and nitrogen content in disturbed sites. In addition, the disturbed sites have lower numbers of threatened and endemic species (15 and 29, respectively) than undisturbed sites (30 and 15, respectively). Linear modelling between soil properties and density indicated a perfect linear relationship for both disturbed and undisturbed sites. Canonical correspondence analysis for disturbed sites indicated sand, silt, clay and bulk density as major controlling factors. The present study indicated a significant impact of anthropogenic disturbances on the alpine floristic diversity and soil properties which needs urgent mitigation actions to conserve the unique and threatened alpine floristic diversity of the Himalayas.