Elevational gradients and species similarities of climate responses for conifers in the southeastern Tibetan Plateau

Abstract

Understanding the growth-climate relationships of trees across different elevations and selecting suitable species for regional climate reconstructions can optimize sampling and analysis efforts. This study developed 17 new tree-ring width chronologies along an elevation gradient from 3100 to 4400 m above sea level (m a.s.l.) on the southeastern Tibetan Plateau. We examined these growth-climate relationships using correlation and response function analyses to identify key growth-limiting factors at different elevations. The radial growth of Smith fir (Abies georgei var. smithii) at 3600–4400 m a.s.l. exhibited positive responses to prior November and July temperatures, but negative responses to May temperatures and June precipitation. For trees below 3600 m a.s.l., Larix griffithii, Pinus densata, and Picea likiangensis showed positive responses to April and June precipitation. The Vaganov-Shashkin model further revealed that June-July temperatures limited the growth of Smith fir above 3600 m a.s.l., whereas early-summer soil moisture was the primary limiting factor below 3500 m a.s.l. This indicates that lower-elevation conifers are more vulnerable to spring-summer droughts. Mixed forests exhibited similar drought responses, with 50–70 % of narrow rings forming during drought years and 20–30 % in the following year. Among those species, P. likiangensis was identified as the most suitable for long-term climate reconstruction due to its greater longevity.