The Hengduan Mountains (HM) harbor diverse vegetation types. Yunnan fir (Abiesgeorgei) along with other high-elevation conifers is an important component of subalpine forest ecoregions in the central HM. Tree growth of high-elevation forests in the HM could response differently along environmental gradients to local climatic variability and long-term climatic trends. However studies on elevational trends of climate-growth responses of high-elevation forests in the HM are rather scant.
Researchers from Xishuangbanna Tropical Botanical Garden (XTBG) developed tree-ring width chronologies of Yunnan fir (Abies georgei) along elevation gradients at two sites (located in the Baima Snow Mountain (BSM) and Shika Snow Mountain (SSM) ) in the central Hengduan Mountains (HM).
The researchers aimed at exploring the dominant climatic factors that determine radial tree growth of high-elevation forests of Abies georgei along elevation gradients in the Hengduan Mountains, and to determine elevational trends in growth rates.
Correlation analyses revealed that tree growth was limited by summer temperature and that the strength and magnitude of growth-climate relationships was enhanced with increasing elevation.
July temperatures are the most important radial growth determining factors for Yunnan fir. The stronger positive relationships with July temperatures in the later sub-period compared to the early sub-period reveal that tree radial growth benefits from increased summer temperatures.
High-elevation Yunnan fir forests in the HM currently benefit from elevated growing season temperatures under humid summer conditions.
The results reveal an elevational trend on tree growth and growth responses to climatic variability of high-elevation Yunnan fir (Abies georgei) forests along elevation gradients from two sites in the central Hengduan Mountains, SW China.