Faster wood formation matters more than longer growing seasons in a warming climate

In non-tropical forests, cold winters hinder tree growth. There, climate warming prolongs the period during which trees absorb carbon through photosynthesis and store it in wood, known as the growing season. This could potentially mitigate further climate change as wood formation and carbon storage increases. But is this really the case?

To find out, an international team including researchers from the Swiss Federal Research Institute WSL analyzed more than 50,000 wood samples from conifer forests across four continents. Their findings have now been published in the journal Science.

Week by week, cell by cell

“Putting together this unique dataset was a long-standing collaborative effort,” says Antoine Cabon, forest ecologist at WSL and the Spanish National Research Council. “Researchers from each partner institute collected wood samples regularly throughout the growing season. Back in the laboratory, each sample had to be processed, photographed under the microscope and analyzed cell by cell.”

The researchers monitored xylogenesis—the formation and development of new wood cells, called xylem cells, found in the outermost tree rings. “By looking at the samples under the microscope, we can see exactly when trees are actively forming wood,” says Cabon. “This allowed us to observe when this process starts and stops, and at what rate it occurs.”