Identifying plant species and communities across environmental gradients in the Western Himalayas: Method development and conservation use

Phytosociological attributes of plant species and associated environmental factors were measured in order to identify the environmental gradients of major plant communities in the Naran Valley, Himalayas. The valley occupies a distinctive geographical setting on the edge of the Western Himalaya near the Hindukush range and supports a high biodiversity; pastoralism is the main land use. There have been no previous quantitative ecological studies in this region. This study was undertaken to (i) analyze and describe vegetation using classification and ordination techniques, (ii) identify environmental gradients responsible for plant community distributions and (iii) assess the anthropogenic pressures on the vegetation and identify priorities for conservation. Phytosociological characteristics of species were measured alongside environmental variables. A total of 198 species from 68 families were quantified at 144 stations along 24 transects across an elevation range of 2450–4100 m. Correspondence Analysis techniques i.e., Detrended Correspondence Analysis (DCA) and Canonical Correspondence Analysis (CCA) were used to determine vegetation–environment relationships. Results show vegetation changes with altitude from moist-cool temperate communities characterized by woody species, to more dry-cold subalpine and alpine herbaceous communities. Plant species diversity is optimal at middle altitudes (2800–3400 m); at lower altitudes (2400–2800 m) it is reduced by anthropogenic impacts and at higher altitudes (3400–4100 m) by shallow soils and high summer grazing pressure. A large number of plant species of conservation concern were identified in the study and an assessment made of the main threats to their survival.