Temporal changes in species richness, composition and diversity of the forest stands over 36-year period, Western Himalaya, India

Abstract

This study investigates the temporal changes in species richness, composition, and diversity in forest stands spanning a 36-year period in the Western Himalaya. Four forest stands (subtropical Sal-forest, subtropical Chir-pine forest, temperate Banj-oak forest, and temperate Mixed-oak Forest) studied in 1980-1981 were resurveyed using similar methods. Over the past 36 years, 19 new species have been recorded in the four stands; eight species planted and eleven species naturally introduced. Dominant species continue to dominate in the forest stands. However, their contribution to the total tree density has decreased over the year. Species diversity, richness, and evenness increased in all forests except the Sal stand. Three species were newly introduced in the Sal stand, seven in the Chir-pine stand, eight in the Banj-oak stand, and seven in the Mixed-oak stand. The highest similarity in species composition was observed in the Sal stand (59%), followed by the mixed-oak stand (57%), Chir-pine stand (50%), and Banj-oak stand (47%). The results indicate an increase in tree density across all sites, with the Mixed-oak forest exhibiting the highest increase in tree density due to least biotic pressure. The findings of this study, based on two-time composition datasets, provide valuable insights into forest dynamics, supporting biodiversity conservation and management planning.