Tree-Ring Based Age-Girth Stand Structure of Himalayan Fir Along the Treeline Transects in Western Himalaya: An Ecological Perspective

Subalpine forests are the important indicators of climate change, future biomass stock under the forest densification and treeline fluctuations. Analyzing the stand structure and growth behavior of trees is essential for the assessment of forest functioning, biomass potential and sustainable management of forest resources. This paper presents the girth and age stand structure of <i>Abies</i> sp. (silver fir) from the treeline ecotones in the summer monsoon dominant and winter westerly dominant regions in the western Himalaya. The age and girth class analysis of fir trees from the four different treeline transects revealed the presence of mixed age and girth class within the treeline ecotone. Fir trees established around 200 years ago in the treeline ecotone with subsequent densification. The fir treeline however showed static behavior during the later part of 20^th century. We also found variations in the girth size increment with age amongst the fir trees, which is statistically significant for the trees growing at the treeline ecotone. The study could help in better evaluation of the changes in the health of trees of treeline ecotone and the factors controlling the treeline fluctuations.