Long- and short-term impacts of climate and dry-season on wood traits of Cedrela fissilis Vell. in southern Brazilian Amazon

Abstract

During the last two decades the tropical Amazon forests have been impacted by frequent and severe droughts. However, little is known about the impacts of these extreme events on wood traits. In this study, we quantified long- and short-term impacts on growth and wood density response and resilience strategies under extreme droughts, analyzing the wood trait trends and correlations with climate variables (temperature, precipitation, and the SPEI drought index). Then, we simulated tree-ring formation and its responses to soil moisture using the process-based VS-Lite growth model. Our results showed how climate anomalies and dry spells increased since 1990s in the southern Amazon region and have affected the growth and wood density of C. fisillis. Ring width, latewood width and minimum wood density experienced the highest sensitivity to drought. C. fissilis showed wider (narrower) and more (less) dense rings during wetter (drier) years, respectively, suggesting that the species undergoes functional plasticity in the formation of its wood in order to adapt to dry conditions. Changes in water limitations during the dry season modify growth thresholds and long-term resilience, leading to decrease growth and increase wood density, enhancing the vulnerability of C. fissilis to projected climate warming scenarios. The short-term resilience is evidenced more in wood density than in the ring width, indicating the species’ ability to adapt to short drought periods. This study is a first attempt to evidence the characteristics of the annual growth rings of C. fissilis trees in relation to climate sensitivity and resilience to drought, based on long-term data from the seasonal moist tropical forest of the Amazon.