Forest‐Wide Growth Rates Stabilize After Experiencing Accelerated Temperature Changes Near an Alaskan Glacier

• Published in: Geophysical research letters Vol. 51; no. 16
• Main Authors: Gaglioti, B. V., Mann, D. H., Wiles, G. C., Andreu‐Hayles, L., Hansen, W. D., Wiesenberg, N.
• Format: Journal Article
• Language: English
• Published: Washington John Wiley & Sons, Inc 28.08.2024; Wiley
• Subjects: Carbon capture and storage; Carbon cycle; Carbon sequestration; Climate change; Climate prediction; Climate trends; Coniferous trees; Dendrochronology; Ecosystem services; Forests; Glacier fluctuations; Glaciers; Growth patterns; Growth rate; Net Primary Productivity; Plant species; Primary production; Rainforests; Stability; Summer temperatures; Temperature changes; Temperature trends; Tree growth; Trees; Trends
• ISSN: 0094-8276; 1944-8007
• DOI: 10.1029/2024GL109469

How forests respond to accelerated climate change will affect the terrestrial carbon cycle. To better understand these responses, more examples are needed to assess how tree growth rates react to abrupt changes in growing‐season temperatures. Here we use a natural experiment in which a glacier's fluctuations exposed a temperate rainforest to changes in summer temperatures of similar magnitude to those predicted to occur by 2050. We hypothesized that the onset of glacier‐accentuated temperature trends would act to increase the variance in stand‐level tree growth rates, a proxy for forest net primary productivity. Instead, dendrochronological records reveal that the growth rates of five, co‐occurring conifer species became less synchronous, and this diversification of species responses acted to reduce the variance and to increase the stability of community‐wide growth rates. These results warrant further inquiry into how climate‐induced changes in tree‐growth diversity may help stabilize future ecosystem services like forest carbon storage. Plain Language Summary Knowing how ecosystems responded to rapid climate changes in the past can help society prepare for the unprecedented rates of change expected in the future. Here, we take advantage of a natural experiment in which a fluctuating glacier caused a temperate rainforest to experience accentuated climate trends similar to those predicted to occur globally over the coming century. As climate changes became accentuated, tree species that once grew in unison shifted to more diversified growth patterns, which unexpectedly caused less variance and greater stability in community‐wide growth rates. Similar diversified growth responses may become important in stabilizing rates of forest carbon sequestration elsewhere. Key Points A glacier‐adjacent forest in Southeast Alaska serves as a natural climate change experiment Dendrochronology reveals that asynchronous species growth rates enhanced the forest‐wide growth stability during accelerated climate trends