Growth responses of Abies spectabilis to climate variations along an elevational gradient in Langtang National Park in the central Himalaya, Nepal

Studies on tree-growth responses to climatic variations in a subalpine ecoregion of the central Himalaya are limited. The Himalayan silver fir (Abies spectabilis (D. Don) Spach), a dominant tree species in subalpine forest on mesic north-facing slopes, was used to analyse the tree-growthclimate relationship along an elevational gradient. Tree growth shows sensitive responses to both growing-season and non-growing season temperature and precipitation variability at all elevations. Temperature has a strong influence at the boundaries (highest and lowest elevation) of the forest range. The uppermost tree-limit boundary is strongly associated with summer temperature, and the lowest forest boundary with winter temperature. Autumn temperatures (November, prior to growth year) influence tree growth regardless of elevation. Premonsoon precipitation has a significant influence on growth only at intermediate elevations. As the study describes the response pattern from only a mesic area, more studies covering a range of climate regimes are required to see whether there is a clear pattern of species-specific growth responses to climate variables along an elevational gradient.