Regional climate and vegetation interactions in the high-altitude forests of North Sikkim, eastern Himalaya: A palynological approach

The coupled interfaces of vegetation and climate in forested regions of monsoon-dominated eastern Himalaya are controlled by spatial-temporal changes in various environmental factors. To detect the variation in vegetation through the changing altitudes of this eastern Himalaya region, modern pollen rain records of surface deposits from various localities at North Sikkim were analysed. This study attempts to contribute towards the understanding of empirical changes across this complex vegetation persisting at an altitudinal range of 2500–4400 m a.s.l. in the North Sikkim region of the eastern Himalaya, India. The samples were predominantly gathered from diverse localities spanning a range of altitudes and varying vegetation distributions, leading to distinct variations in the pollen yield across the different sites. The quantitative multivariate statistical analysis, such as Redundancy Analysis and Cluster Analysis, are applied to this palynological data set, effectively elucidate the variations in modern pollen spectra. The mean annual precipitation (MAP) and mean temperature of the warmest month (MTWA) are the climatic variables strongly influencing the modern pollen rain recorded in these high-altitude regions of the eastern Himalaya.