Indian Himalayan Timberline Ecotone in Response to Climate Change – Initial Findings

This article enumerates the findings of a team research on the Indian Himalayan timberline ecotone, with focus on three sites (located in Kashmir, Uttarakhand and Sikkim). Timberline elevation increased from west to east, was higher in the warmer south aspect than the cooler north aspect, and was generally depressed. Betula, Abies, Rhododendron and Juniperus were important treeline genera. The Himalaya has not only the highest treelines (Juniperus tibetica, at 4900 m), but also the widest elevational range (>1700 m). Remotely sensed data revealed that the timberline is a long, twisting and turning ecotone, traversing a length of 8–10 km per km horizontal distance. Surface temperature lapse rate in the monsoonal regions was lower (–0.53°C/100 m elevation) than generally perceived and varied considerably with season, being the lowest in December. The Himalayan treeline species are not water-stressed at least in monsoonal regions, predawn tree water potential seldom getting below –1 MPa. The upward advance of Rhododendron campanulatum (a krummholz species) may deplete alpine meadows with climatic warming. Tree-ring chronology indicated that winter warming may be favouring Abies spectabilis. Early snowmelt increased growth period and species richness. Treelines generally are stable in spite of decades of warming. Dependence of people on timberline was still high; so economic interventions are required to reduce the same.