Forest Carbon Coalition – Science Synthesis

Why is it so important to NOT log big, old trees on federal lands?

It is impossible to overstate the importance of big, old trees on federal lands. Much of this importance comes from being big and old. As they grew, over decades or more, they removed large amounts of carbon dioxide from the atmomsphere, and thereby reducing the speed and severity of climate the crisis. Logging these big, old trees would release much, if not almost all of this carbon back into the atmosphere, making the climate crisis worse.

To see the full importance of big, old trees, though, one must look not just at the trees themselves, but also at the many roles they play in creating a healthy forest. Through their roots and interrelationships with soil fungi, they help younger trees get established and grow, by supplying nutrients and water. That’s right—big, old trees help younger trees survive and grow. Their broad shade cools and helps maintain moisture levels in the underlying soil, so that low-lying vegetation can withstand drought conditions and resist wildfire. They provide habitat for numerous species that have evolved over millennia to co-exist with big, old trees.

Their influence on habitats and species often extends much farther. In many settings, for example, they reach up into winter fog, where water droplets condense on their leaves and twigs, drop to the ground, leach into shallow groundwater, and reemerge in summer to maintain streamflows many fish and other aquatic species need to survive. These higher streamflows also can be important sources of water for downstream irrigators and urban consumers.

Logging big, old trees on federal lands can eliminate, or at least dramatically reduce, all of these valuable benefits. As a result, the climate crisis will become worse; federal forests will become less healthy; and species dependent on big, old trees will become more exposed to risks of declining population.

Key research on the importance of big, old trees:

Bramadat-Willcock, M. 2022. Experts Are Looking into How Mother Trees Can Help Reduce Risk of Wildfires in Northern B.C. Terrance Standard online.

Link: https://www.terracestandard.com/news/experts-are-looking-into-how-mother-trees-can-help-reduce-risk-of-wildfires-in-northern-b-c/  with reference to https://www.amazon.com/Finding-Mother-Tree-Discovering-Wisdom/dp/052565609X .

Key excerpts:

  • “The big old trees help protect biodiversity, keep carbon in the ground and help regenerate the next forest.”
  • Trees might not look like they’re connected but Simard said they do “communicate” with each other below ground through a network of root systems and fungi that transmits and exchanges nutrients between them. The “mother trees” are important hubs for those networks.
  • “The little seedlings that come up around these old trees hook into that network supported by the old trees,” Simard said. “The old trees send nutrients, water and carbon directly into these little seedlings and help them get going.”
  • She said there is a 20 to 30 per cent increase in seedling survival when the bigger trees are left standing. The older trees also keep the ground moist and protect seedlings from drying up in the summer.
  • “These old trees are really important in regenerating the next forest. When you leave old trees, the biodiversity of the ecosystem is also protected,” Simard said. “They also help reduce wildfire in these ecosystems because they have thick bark that can resist the fire.”

Hussan, Z., 2022. Friendly fungi help forests fight climate change. BBC News online, June 19th, 2022.

Link: https://www.bbc.com/news/science-environment-61787248

Key excerpts:

  • “The trees in our forests absorb carbon dioxide from the atmosphere as they photosynthesise; their leaves, powered by sunlight, convert that carbon dioxide into oxygen and sugar. As a tree grows, the carbon becomes part of its woody ‘biomass’.”
  • “Trees though do not act in isolation; they are entangled with – and working alongside – a vast community of micro-scale fungi. These fungi live in the root system of a host tree. In a symbiotic relationship, fungi help the tree to absorb more water, carbon and other nutrients. In exchange, the tree provides food for the fungi by photosynthesising. Ectomycorrhizal fungi have also been found to slow down the process of rotting; decomposition breaks down all that locked-away carbon and releases it into the atmosphere. So the fungi, in effect, have two methods of fighting global warming.”


A mesh of underground fungi plays an important role in energy and nutrient cycling

Cannon, C.H., G. Piovesan, and S. Munne-Bosch. 2022. Old and Ancient Trees Are Life History Lottery Winners and Vital Evolutionary Resources for Long-Term Adaptive Capacity.

Link: https://www.nature.com/articles/s41477-021-01088-5

Key excerpts:

  • “Old and ancient trees cannot be replaced through restoration or regeneration for many centuries. They must be protected to preserve their invaluable diversity.”
  • “The ecological importance of old trees in forested ecosystems has been extensively documented, particularly as small natural features that provide a wide range of services[citations].”