ENVIRONMENTAL FEEDBACKS OF THE SUBALPINE ECOTONE SPECIES IN THE LANGTANG NATIONAL PARK, CENTRAL NEPAL HIMALAYA
Abstrakt
An acute sensitivity of ecotone vegetation to environmental changes makes ecotone vegetation dynamics as one of the prime aspects in vegetation ecology. Understory vegetation of ecotone can indicate the changing environmental conditions of the region by showing its own growth pattern, abundance, and assemblages.
Our study aims at investigating the compositional pattern of herbaceous species of a subalpine ecotone in Langtang National Park, central Nepal and analyzing their responses to the different environmental factors. We performed multivariate analyses to study species composition, and for analyzing individual plant species responses logistic regression was used.
It was observed that profound variation in the canopy cover and soil organic carbon along the ecotone significantly influenced the species composition of the herbaceous vegetation. Response curve analysis showed the most significant response of eleven least tolerance species to the environmental variables.
Gentiana argentea, Geranium donianum, Kobresia sp., Potentilla griffithii, Rubia wallichiana, Rubus nepalensis, Thalictrum chelidonii and Thalictrum cultratum were particularly important because these species had narrow amplitude to both the studied environmental variables - canopy cover and soil organic carbon. As these species could be critically sensitive to even minor fluctuation in the environmental factor(s), can be regarded as potential indicator species of the respective environmental variable.
These indicator species could be vital in understanding community dynamics of the vulnerable ecotone vegetation within the National Park via their use in long-term assessment of the habitat conditions. Replicated studies at broader scales would further be important for understanding the dynamics of the other ecotone plant communities of Nepal Himalaya.