Add to this diagram – “Respiration (when overheated).”
We’ve talked about how older forests may sequester less carbon and dead forests release carbon (for example, here). New research indicates that forests also sequester less carbon and start to release carbon (while they are still alive) if the temperature gets too high. As reported here:
‘We’re in Bigger Trouble Than We Thought’
The data show a clear temperature limit, above which trees start to exhale more CO2 than they can take in through photosynthesis, said co-author Christopher Schwalm, an ecologist and earth system modeler at the Woodwell Climate Research Center. The findings mark a tipping point, of sorts, at which “the land system will act to accelerate climate change rather than slow it down,” Schwalm said.
“Seeing such a strong temperature signal globally did not surprise me,” he said. “What I was surprised by is that it would happen so soon, maybe in 15 to 25 years, and not at the end of the century.”
Other researchers commented on management implications of drought-stressed dying trees:”
It may come down to looking at options for saving valuable, individual stands of trees, and protecting genetically distinct and more resilient species. It could also be important to conserve corridors and patches of woodland to reduce the distance seeds must travel to enable forests of the future to spread or reconnect under more favorable climate conditions, he explained.
“We think a lot of these areas are going to go down, so where can we save some of it?” he asked.
There are obviously implications here for national forest planning. It seems like it should be the role of the national headquarters to review and interpret the implications of new research for forest management, and to advise national forests regarding its implications for their plans and whether they should consider making changes.