This correspondence refers to a recent note about monitoring alpine treeline in the Western Himalaya and few other
recent studies on the same aspect. Alpine zones in the Himalayas are the highest vegetation zones where seedbearing plants are found, but tree growth is excluded. Upper and lower boundaries of alpine zones are traditionally set as
‘snowline’ (lowermost limit of permanent snow) and ‘timberline’ (uppermost limit of closed montane forests) respectively. Since alpine ‘treeline’ is the uppermost limit of the trees, it also marks the uppermost end of ‘timberline ecotone’ or forest tundra ecotone (transition zone between montane forests and alpine zones), which starts at the timberline at the lower end. Despite the use of the word ‘line’, any natural boundary itself is a transition zone. Treelines are temperature-sensitive zones that are expected to respond to climate warming by advancing beyond their current position. (Correspondence)