Size‐, species‐, and site‐specific tree growth responses to climate variability in old‐growth subalpine forests

Abstract Tree‐ring data have become widely used to model tree growth responses climate variability and gain insight about the potential effects of global warming on forests. We capitalized a rare opportunity develop growth–climate models using tree‐ring collected from all trees (>4 cm in diameter at breast height) within 50 × m plots established subalpine old‐growth forests western Canada. Our objective was determine how vary among size classes, species, sites. modeled relationships between times series annual basal area increment (ΔBA) yearly variables for individual trees; this approach obviated key statistical criticisms “traditional” analysis methods. Time were detrended priori size, age, legacy, competition effects. found that overall signal our time ΔBA weak; <6% interannual variance explained by variables. Nevertheless, there clear patterns climate–growth related species. Relationships five increased strength with class; large most sensitive fluctuations accounted ~71% effect across In stands, stable over 20th century but decreased 1940s small trees, indicating temporal reduction sensitivity coastal forests, Callitropsis nootkatensis significantly different direction magnitude than those co‐occurring Pinaceae The idiosyncratic stands could not be discriminated forest type (coastal vs. interior). individual‐tree modeling adds growing body research providing novel insights complexities challenges associated predicting future productivity data.