Criteria and indicator for assessing threat on Himalayan birch (B. utilis) at timberline ecotone of Nanda Devi Biosphere Reserve: A world heritage site, Western Himalaya, India

Abstract

Abstract Western Himalayan timberline are mainly dominated by Betula utilis (Himalayan birch) and closely associated with Abies spectabilis, Quercus semicarpifolia and Taxus baccata and formed the ecotone between the coniferous forest and alpine areas. Himalayan birch is socio-culturally and ecologically valued and considered a keystone species which plays significant role in the functioning of timberline ecosystem. A total of 13 timberline ecotone of pure Himalayan birch forests were selected to assess the magnitude of threat on dominant plant species using rapid threat assessment and rapid vulnerability assessment. It form the basis to design appropriate criteria, indicators and scores (ranging from 1 to 4) to rank the plant species under various threat categories. Besides, phytosociological studies were undertaken for assessment of species diversity, density and regeneration potential. The paper highlighted individual of Himalayan birch is declining in adult stages, however growth and vigor observed in seedling and sapling stages. Despite, Himalayan birch was found the most vulnerable species with a threat score of 29 followed by Taxus baccata and Juniperus communis. The annual exploitation of Himalayan birch estimated about 927.10 ​kg capita−1 yr−1 fuelwood and 551.15 ​gm capita−1 yr−1 bark by the people involved in collection of Ophiocordyceps sinensis. The current trends of unsustainable exploitation would facilitate the decline in population of the some ecological important species particularly Himalayan birch. Therefore, this study suggests the appropriate policies and strategies for conservation and management of Himalayan birch on one hand and socio-economic development of local communities on the other.