Population structure and regeneration status of rhododendrons in temperate mixed broad-leaved forests of western Arunachal Pradesh, India

摘要

ABSTRACT This study was conducted to investigate the population structure and regeneration status of Rhododendron tree species in temperate mixed broad-leaved forests in Tawang and West Kameng districts of western Arunachal Pradesh, India. Population structure was determined through densities of seedlings, saplings and adults from the sampling quadrats. Based on density of individuals at the seedling, sapling and adult, the regeneration status of the species was determined. Density and basal area of the selected rhododendrons ranged from 16 individuals ha~(?1)to 1422 individuals ha~(?1)and 0.24?m~(2)?ha~(?1)to 131.30?m~(2)?ha~(?1), respectively. Rhododendron species (viz. R. arboreum, R. arboreum ssp. delavayi var. delavayi, R. barbatum and R. kesangiae ) exhibited reverse J-shaped distribution with the density of sapling less than seedling and adult population. Density of selected Rhododendron species is found to be higher between the girth classes 10-30 cm to 130-150 cm and decreased with the increase of girth in all the study stands. About, 90% degrees of disturbances recorded due to cooking and space heating purposes. Among the regenerating species, 77% of the species exhibited fair regeneration, 8% species showed good regeneration while 15% of the species exhibited no regeneration. However, 90% of the tree species showed fair regeneration in disturbed stands than the undisturbed stands. Selected Rhododendron species exhibited fair regeneration in their respective stands. Inadequate regeneration status and population structure of tree species, including rhododendrons, are observed as the density of sapling less than seedling and adult population. Anthropogenic disturbances resulted to be declined in populations of Rhododendron and may lead many species to endangered, rare and threatened categories. Therefore, proper conservation and management initiatives with active involvement of local people are urgent need to protect this keystone plant species in their habitat particularly in western Arunachal Himalaya.