Elevation Pattern in Growth Coherency on the Southeastern Tibetan Plateau

Area of Science:

• Ecology
• Forest Science
• Climate Change Research

Background:

• Alpine forests face harsh climatic conditions with increasing altitude.
• It is generally expected that tree radial growth patterns converge with rising elevation due to environmental stress.

Purpose of the Study:

• To investigate altitudinal patterns of tree growth, climate sensitivity, and growth synchrony in alpine forests.
• To determine if tree growth converges at higher elevations on the southeastern Tibetan Plateau.

Main Methods:

• Collected increment cores from Balfour spruce (Picea likiangensis var. balfouriana) at lower, middle, and upper forest limits.
• Measured, crossdated, and detrended tree-ring widths to obtain ring-width indices.
• Analyzed annual growth rate, climate sensitivity, growth-climate relationships, and growth synchrony across altitudes.

Main Results:

• No significant difference in annual growth rate across altitudes was observed in Buze Mountain.
• Tree sensitivity to winter temperature increased with altitude, while growing season moisture response decreased at treelines.
• Growth synchrony among individual trees decreased at higher elevations, contrary to expectations.

Conclusions:

• The study's findings do not support the general expectation of growth convergence with increasing altitude.
• Individual heterogeneity and microhabitat diversity are key factors influencing treeline tree growth and dampening synchrony.
• Results highlight the importance of considering individual tree variations in high-elevation forest growth studies.