Combined view of various tree ring parameters from different forest habitats in Tibet for the reconstruction of seasonal aspects of Asian Monsoon variability

Abstract

Tibetan forests cover a wide range of ecological habitats. Three different types of tree limit can be derived from statistical climate-growth relationships: An alpine timberline, where growth is limited by temperature conditions, a semiarid tree limit, where availa­ble moisture is the minimum factor for tree growth, and dry, southfacing exposures near the upper treeline, where growth can be limited as well by temperature as by moisture conditions. Trees at each of these sites, which belong to the genera Pinus, Picea, Abies and Juniperus are sensitive to specific seasonal climatic elements e.g. summer precipi­tation, summer or winter temperature. The potential for the selective reconstruction of different seasonal aspects of climate is enhanced by considering different tree ring pa­rameters like total ring width (TRW), maximum latewood density (MLD), wood ana­tomy and the content of d 13 C in wood cellulose. The combination of these seasonal cli­mate related parameters provides a more comprehensive view of climate variability over the year, allowing the reconstruction of synoptic weather conditions. These are much better indicators for wind system dynamics and monsoon variability than one single meteorological factor alone. Since juniper can reach living ages of more than 1300 years in Tibet, dendroclimatological studies offer the possibility to reconstruct monsoon variability on the Tibetan plateau and adjacent regions during the last millenium.