Effect of topographical gradient and edaphic factors on the beta diversity of Western Himalayan forests

In Himalayan forests, altitude, slope angle and aspect are the three main factors that govern the overall structure and function of the ecosystem. Understanding and predicting how vegetation will respond to increasing climate change is of utmost importance for maintaining ecosystem functions and services in the Himalayan region. Variation in micro-climatic conditions and diversity occurs due to change in elevation and other biotic factors. Here, we tried to assess the effect of topography and edaphic factors on beta diversity and vegetation association pattern along an elevational gradient of 400m to 3000m asl having differences in slope aspect (North and south). We established 200 100m2 quadrats at 10 different sites (5 elevation zone × 2 aspects) spanning from sub-tropical to temperate forests for tree and shrub species. We used cluster dendrogram to assess the association of species, Jaccard’s index to estimate the similarity in species composition and regressed the values against the logarithm of the distance between the plots to assess beta diversity. Among all the sites, beta diversity was found to be higher for higher elevational sites. Soil properties were strongly related to beta diversity and it did not differ much between the opposite aspect thus confirming, elevation to play an important role in governing beta diversity in Himalayan forest ecosystems.