August 13, 2021
News Release

Survival Strategy of Starving Spruce Trees: The Critical Role of Reserves

Young spruce trees subjected to extreme conditions turn to self-digestion, ramp up reserves

This split image shows potted spruce trees, left, and spruce trees enclosed in containers with low CO2 concentrations, right.

Spruce trees, shown left, were sealed inside containers with low levels of CO2, shown right. The experimental setup simulates climate extremes, where water is scarce and CO2 uptake is low, so researchers may better understand how forests will fare in a warmer world.

(Photo provided by the Max Planck Institute for Biogeochemistry)

When faced with climate extremes, some trees still stockpile energy reserves, even if that means self-digestion, according to a new study conducted by researchers at the Max Planck Institute for Biogeochemistry in Jena, Germany, and the U.S. Department of Energy‘s Pacific Northwest National Laboratory. The findings, published today in the journal Proceedings of the National Academy of Sciences, paint an increasingly accurate picture of how forests may fare within a changing climate.

In an experiment designed to explore tree energy storage in extreme conditions, researchers grew young spruce trees in sealed containers where carbon dioxide concentrations were kept low. Plants pull CO2 from the surrounding atmosphere, using it to both fuel everyday functions and build tissue. In drought conditions, when CO2 uptake is low and water is limited, it’s expected that trees would produce fewer energy reserves.

Instead of shutting down the important process of energy storage, however, the deprived trees stopped growing, then began producing more enzymes linked with readily accessible energy storage compounds. Despite difficult conditions, they ramped up energy reserves.

"It seems that plants prefer to sacrifice expendable structures and apparently even digest themselves, rather than to give up on storage formation,” said Henrik Hartmann, a coauthor of the study and group leader at the institute. PNNL Earth scientist Nate McDowell, an expert on the role of climate-related stress on forests, contributed to the research study.

For more information, see the news release provided by the Max Planck Institute for Biogeochemistry.


About PNNL

Pacific Northwest National Laboratory draws on its distinguishing strengths in chemistry, Earth sciences, biology and data science to advance scientific knowledge and address challenges in sustainable energy and national security. Founded in 1965, PNNL is operated by Battelle for the Department of Energy’s Office of Science, which is the single largest supporter of basic research in the physical sciences in the United States. DOE’s Office of Science is working to address some of the most pressing challenges of our time. For more information, visit For more information on PNNL, visit PNNL's News Center. Follow us on Twitter, Facebook, LinkedIn and Instagram.

Published: August 13, 2021