Gori-Ganga valley in Pithoragarh district, Uttaranchal, forms a part of Askot Musk Deer Sanctuary and Nanda Devi Biosphere Reserve. The Birdlife International-BNHS, Important Bird Area programme has listed it as an ‘IMPORTANT BIRD AREA’. Gori-Ganga valley captures the entire gradient of Himalayan habitats ranging from subtropical Sal to Alpine meadows within a distance of about a hundred km of the river from its confluence to source.The patterns of diversity and abundance in birds and woody plants, along the entire gradient is analyzed, the similarity and differences between these two distinct taxonomic groups and the mechanisms related to these patterns and their conservation significance is discussed.Composition of both plants and birds are strongly governed by altitude. The compositional changes along the gradient were congruent and seem to be generated by a common mechanism. Himalayas are known to be a meeting point of three biogeographic realms. The floral and faunal diversity of these very different realms arrange themselves altitudinally along climatic zones most favourable to each group.

Diversity of both the groups showed contrasting patterns yet some similarities. Plant species diversity declines with altitude, whereas bird species diversity seems to have plateau and then declining relationship with altitude. Though in both groups highest diversity did occur at low elevations. The interpolated richness showed multimodal patterns in both cases and the peaks are coincident with ecotonal effects or zonal feedbacks.

The distribution and abundance relationship is remarkably congruent in both woody plants and birds. Strong positive correlations were observed between different measures of frequency of occurrence and abundance. Altitude range, a measure of environmental amplitude of species also relates positively with frequency and abundance. Thus species, which occur less frequently in the landscape, also tend to occur in low abundance and species which occur with greater frequency tend to occur at higher average abundances. This relationship is a general ecological pattern.

Densities of both plant and birds seem to be strongly constrained by individual energetic needs, which are set by their body sizes. There is a  strong negative relationship between density and size in body size classes. This relationship helps to set the upper bound to abundance of species. Species of particular body sizes achieve their highest abundances below or at the limit set by their energetic requirements.

The Gori valley presents an exceptionally diverse assemblage of flora and fauna in a very short geographical span. A central reason for this wonderful display of biological diversity in the Gori basin is its large altitude gradient represented in a short geographical spread. The adequate conservation of its diversity would require protecting representative sites in each of its elevation zones. Therefore it is of vital importance that the integrity of the entire landscape be conserved and managed for biodiversity and not just high altitude habitats for a single species such as musk deer or snow leopard. Indeed, the importance of this landscape is much greater.
 

Diversity and rarity in floral and avifaunal assemblages in the Western Himalaya: A study of patterns and mechanisms to devise viable biodiversity conservation strategies.

02.07.2001 to 11.07.2005