Hydraulic Trait Strategies Lead to Divergent Tree Growth Responses to Multidecadal Climate Variability

Abstract

Climate change, including altered precipitation patterns, is impacting the growth, competition, survival, and carbon allocation dynamics of trees globally. Using 22 years of data, we aimed to link the strength and timing of species‐specific stem growth responses to water stress and species‐level hydraulic strategy traits. We measured gross primary production (GPP) as well as environmental factors including soil water content, vapor pressure deficit, and photosynthetically active radiation within the footprint of the AmeriFlux US‐UMB site, a temperate deciduous forest in northern Michigan. We recorded annual stem growth increments of individuals encompassing eight species using band dendrometers and calculated annual changes in biomass using allometric equations. Yearly stem growth for each species was compared to mean environmental conditions over 3‐month seasonal periods from the same and previous year to account for potential lags between climate and growth signals. At the ecosystem level, no correlation between measured changes in aboveground biomass and GPP was observed for the current and prior years, suggesting divergent temporal carbon allocation patterns that vary among species. In our forest site, the growth of white pine was negatively correlated with growing season soil water content, in contrast to most measured species, indicating that drought affected the competitive interactions of species with different hydraulic traits. These contrasting trends and asynchrony with GPP reiterate the need for consideration of hydraulic trait strategies in carbon modeling.