Mohamed Latif Khan

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

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 m2 ha−1 to 131.30 m2 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.

Anthropogenic Disturbances Led to Risk of Extinction of Taxus wallichiana Zuccarini, an Endangered Medicinal Tree in Arunachal Himalaya

ABSTRACT: Species extinction is the major biodiversity crisis in the twenty-first century. Today, anthropogenic activities are causing extinction of many species of ecological and economic importance. Arunachal Pradesh, home of high biodiversity and endemism, has many species facing tremendous stress which are on the verge of extinction. Taxus wallichiana, an endangered tree species distributed in temperate forests, has the anti-cancerous chemical Paclitaxel (Taxol®). It has other important uses in Ayurveda, Tibetan, and Unani medicine. Currently, Taxol is recognized as the most effective drug for a variety of cancers. Owing to its high economic demand, unsustainable extraction, and over-harvesting, the species ranked in the endangered category and is at risk of extinction in Arunachal Himalaya. Regeneration from seed is very poor due to a long dormancy period (nearly 18 months) and it is slow to reach maturity in nature. Moreover, consumption of fruits by birds, monkeys, rats, etc., is causing regeneration failure. A very few populations survive in isolated pockets and they will become extinct in the near future if proper conservation measures are not initiated. Conservation measures either by in situ or ex situ, with community participation, can be undertaken. In situ conservation can be exercised by establishing sanctuaries, parks, reserve forests, etc. Ex situ conservation could be practiced by cultivating the species in gardens, parks, and also by tissue culture techniques. Furthermore, mass awareness and motivation of local people for large scale cultivation and preparation of bonsai to a certain height to harvest the leaves without damaging the whole tree may reduce pressure on wild populations. This may meet the market demand as well as conserve the species and will boost the rural economy while also providing employment opportunity for the local inhabitants.