Plant Species Diversity along an Altitudinal Gradient of Bhabha Valley in Western Himalaya

The present study highlights the rich species diversity of higher plants in the Bhabha Valley of western Himalaya in India. The analysis of species diversity revealed that a total of 313 species of higher plants inhabit the valley with a characteristic of moist alpine shrub vegetation. The herbaceous life forms dominate and increase with increasing altitude. The major representations are from the families Asteraceae, Rosaceae, Lamiaceae and Poaceae, suggesting thereby the alpine meadow nature of the study area. The effect of altitude on species diversity displays a hump-shaped curve which may be attributed to increase in habitat diversity at the median ranges and relatively less habitat diversity at higher altitudes. The anthropogenic pressure at lower altitudes results in low plant diversity towards the bottom of the valley with most of the species being exotic in nature. Though the plant diversity is less at higher altitudinal ranges, the uniqueness is relatively high with high species replacement rates. More than 90 % of variability in the species diversity could be explained using appropriate quantitative and statistical analysis along the altitudinal gradient. The valley harbours 18 threatened and 41 endemic species, most of which occur at higher altitudinal gradients due to habitat specificity.

Distribution of plant species along the elevation gradient in Pangi, a high altitude and remote eco-region in Western Himalaya, India

The Himalayan high-altitude eco-regions exhibit higher plant species diversity, and several environmental factors play a crucial role in shaping species distribution and diversity. The aim of the present study is to investigate the floristic composition, distribution of endemic, threatened and native taxa across the elevation zones and the effect of various environmental factors on species richness pattern along the elevation gradient in Pangi, a remote highaltitude region of Himalaya. We conducted extensive field surveys covering 31 localities and established elevational transects for assessing species distribution and the factors affecting thereof. Additionally, information on nativity, endemism, and IUCN red-list categories of threatened species were compiled from published and online resources. Data were analysed using regression model and Non-Metric MultiDimensional Scaling(NMDS). In the present study, we recorded a total of 771 plant species across the region. In regression model, the elevation and anthropogenic variables and their interaction showed significant negative effects on the species richness. Species richness was found to decrease with the increasing elevation, showing a humped shaped pattern, with maximum richness observed in the mid-elevations(2,400m to 3,300m above sea level). The pattern of distribution of native and non-native species along the elevation gradient showed opposite trends, and proportion of native species increased towards the higher elevations. Further, NMDS ordination suggests that zone-Ⅰ(2,100-2,500m asl) and zone-Ⅴ(4,001-4,500m asl) had highest differences in species composition, while zone-Ⅰ, zone-Ⅱ(2,501-3,000m asl), and zone-Ⅲ(3,001-3,500m asl) showed higher affinity with respect to their species composition. Thus, the present study revealed that remote and hitherto un-explored Pangi eco-region is rich in floristic diversity and provides pertinent information on the species distribution and composition, and various underlying factors influencing the richness patterns, which is necessary for framing suitable conservation strategies, management plans and futuristic population studies.