Abstract ID: 3.13010 | Accepted as Talk | Talk/Oral | TBA | TBA

High elevation ecosystems are among the most vulnerable to climate change. Climatic treelines are expected to shift to higher elevations due to the tight coupling between treeline position and temperature. However, tree species within treeline ecotones may show diverging sensitivities to changes in temperature and precipitation, resulting in altered competitive relationships and ultimately affecting treeline dynamics. Using a dendroclimatology approach, we compared tree growth-climate relationships of Abies spectabilis and Rhododendron campanulatum, two dominant species of Central Himalayan treeline ecotones. We correlated tree ring widths with monthly and seasonal climate data including the Standardized Precipitation-Evapotranspiration Index (SPEI). The moving correlation and response function analysis revealed inconsistent tree growth-climate relationships across time. We found contrasting patterns of climate sensitivity: Abies spectabilis exhibited a strong negative response to pre-monsoon season (March-May) temperature, especially in recent decades, potentially linked to increased drought stress as indicated by responses to precipitation and SPEI. In contrast, Rhododendron campanulatum showed growth responses to temperature of all seasons, especially winter (December-February) and late summer (June-August). Signs of drought stress are less pronounced in comparison to Abies spectabilis. Tree growth–climate correlations are more stable over time indicating greater resilience to climatic variability compared to Abies spectabilis. This difference in climate sensitivity suggests that Abies spectabilis may be more vulnerable to currently changing climate conditions, while Rhododendron campanulatum may be more resilient to climate variability. These findings have important implications for understanding and forecasting the effects of climate change on Himalayan treeline dynamics. A potential expansion of Rhododendron campanulatum expansion relative to Abies spectabilis under predicted warming scenarios could significantly alter the structure and function of Himalayan treeline ecotones.