Douglas-fir (Pseudotsuga menziesii) Blue Intensity Measurements Reveal Precipitation Sensitivity in the Greater Yellowstone Ecosystem

Keywords: Dendrochronology, Blue intensity, Douglas-fir, paleoclimate
Session Type: Virtual Poster Abstract
Day: Sunday
Session Start / End Time: 2/27/2022 03:40 PM (Eastern Time (US & Canada)) - 2/27/2022 05:00 PM (Eastern Time (US & Canada))
Room: Virtual 27

Abstract

Tree-rings provide annually resolved, climate-proxy data that enhances our understanding of past climatic conditions prior to the instrumental record. Recently, visible light techniques such as blue intensity (BI) have become increasingly important for tree-ring based climate reconstructions. In North America, BI has regularly been used to reconstruct summer temperatures, but less is known about the hydroclimate response of BI. In this study, we developed total-ring-width, earlywood, latewood, and delta BI chronologies from 20 individual high-elevation Douglas-fir (Pseudotsuga menziesii), collected from the Greater Yellowstone Ecosystem (GYE). We examined the relationships between total-ring-width and BI measurements and assessed the climate response of each tree-ring parameter. We used a Pearson’s correlation analysis to examine the spatial and temporal relationships between each of the detrended tree-ring chronologies and multiple current-year climate variables: minimum, mean, and maximum temperature, total precipitation, and Palmer Drought Severity Index. The total-ring-width and delta BI chronologies exhibited positive, significant responses to current-year precipitation in June and July, and negative, significant responses to both mean and maximum temperature in June-August. As the sampled trees are located on a southwest-facing slope with poor soil, we suspect that low-quality site conditions are heavily contributing to the dominant summertime moisture stress signal. Our study is the first to examine BI climate sensitivity using Douglas fir. While our results suggest that a hydroclimate reconstruction for the GYE may benefit from using both ring-width and BI predictors, additional work is needed to further examine this matter.