Assessing the dendrochronological and dendroclimatic potential of Shasta red fir (Abies magnifica var. shastensis)

Abstract:

Here we present five new ring-width records from Shasta red fir (Abies magnifica var. shastensis) stands in northern California and southwestern Oregon to evaluate growth trends and their relation to climate across the species’ latitudinal range. The chronologies are made up of 173 living trees in total, and earliest adequate replication ranges from AD 1624 to AD 1812. The oldest tree sampled has an inner-ring date of AD 1340. Chronologies display shared variability in ring-width at inter-annual timescales; however, reliable cross-dating across the full study region is not possible. The five chronologies, together with one publicly available record, were compared to local and regional climate data. Significant correlations between red fir tree growth and local climate were found at all six sites but no relationship was consistent throughout the latitudinal gradient. Prior analysis has suggested that the growth of the species is primarily limited by summer minimum temperature, but this relationship was not apparent at most sites within our network. Instead, the associations observed between red fir growth and climate are multivariate, dependent on the temporal resolution of climate data used, and may also be influenced by both latitude and elevation.