Authors: Raju Bista*, California State University Dominguez Hills, Parveen K. Chhetri, California State University Dominguez Hills, Krishna Babu Shrestha, University of Bergen, Bergen, Norway
Topics: Biogeography, Paleoenvironmental Change, Land Use and Land Cover Change
Keywords: Age structure, Mortality, Pinus wallichiana, Population dynamics, Survivorship, Treeline
Session Type: Poster
Presentation File: Download
Population age structure and dynamics portray the picture of stand history. Age structure analysis in this study has tried to have an insight into the Himalayan Blue Pine regeneration history in the treeline ecotone of Ngawal, the south-facing slope of the trans-Himalayan dry Manang valley. The pine population within three vertical transects of 20 m width were studied. The age of trees was determined from the number of annual rings counted from increment core taken from the tree base. Age of juvenile saplings and seedlings was estimated by counting branch whorls and scars on the stem. Almost reverse J-shaped size and age structure showed the majority of the pine population was recruited recently, especially by and after the 1970s. The current timberline position is ca. 3930 m asl whereas the treeline position in the area is ca. 4020 m asl that with age-height regression is estimated to be attained by early 1990s to remain static thenceforth. Despite the absence of recent treeline advance, as shown from the survivorship and mortality curves, the progressive densification in the treeline ecotone, as well as seedling establishment above the treeline, may indicate the future potential for the treeline advance. The type II survivorship curve may be influenced by the marked release of human pressures as well. Further studies incorporating climate, ecophysiological and anthropogenic aspects are necessary to dig deep into the treeline ecology in the area.