Sensitivity of radial growth of subalpine conifer trees to climate warming on the southeastern Tibetan Plateau

Abstract

Tree growth at alpine regions is sensitive to climate change. However, there is still uncertainty about the spatial and temporal stability of tree growth in response to warming. Herein, through collecting 302 cores from 162 conifer trees at 4 sites of paired timberline and subalpine forests on the southeastern Tibetan Plateau, we analyzed the spatial and temporal pattern of radial growth in response to warming. Response analysis result of standard and first-order difference chronology showed that the variation of radial growth was mainly affected by summer temperature in the Sergyemla Mountains (SGM), Baima Snow Mountains (BSM), and Meri Snow Mountains (MSM), by winter temperature and early summer drought stress at Chagyab (CY). The radial growth in timberline forests is more sensitive to temperature than those in subalpine forests. Growth-temperature sensitivity generally decreased during the past 60 years. The analysis of the Standardized Precipitation Evapotranspiration Index (SPEI) indicated that the drought stress was one of the main reasons for the variation of temperature insensitivity, suggesting that the moisture condition may play an increasingly important role on tree growth in warming future.

Keywords

• Tree-ring width
• Spatial and temporal pattern
• Climate change
• Timberline and subalpine forest
• “Divergence problem”