Older forests are less vulnerable to climate change than their younger counterparts — particularly in regards to carbon storage, timber production, and biodiversity levels.
The study, led by members from the University of Vermont, looked at how climate change is expected in alter forests across Canada and the United States. All in all, they report, forests are less sensitive to higher temperatures and precipitation levels as they age, being better able to retain biodiversity, timber production, and the ability to store carbon.
The old that is strong does not wither
“This study shows that older forests in the Upper Midwest to New England are uniquely resilient to climate,” says Dominik Thom, lead author and postdoctoral researcher in UVM’s Rubenstein School of Environment and Natural Resources and Gund Institute for Environment.
“Our finding that essential services are better protected against climate change by older forests is a milestone in the debate on how to prepare our forests for the uncertain environmental conditions ahead.”
In short, the study found that age helps protect forests from the effects of climate change.
The team worked with a huge body of data recorded from over 18,500 forest plots from Minnesota to Maine, and Manitoba to Nova Scotia. One of their main focuses was to identify which areas should take priority in regards to forest climate adaptation efforts. Younger forests east and southeast of the Great Lakes were less resilient to climate change, showing declines in carbon storage, timber, and biodiversity compared to older ones.
“Our study identifies opportunities to make forest management more adaptive to global change,” says William Keeton, forestry professor in UVM’s Rubenstein School and Gund Institute.
“This could include enhancing older forest conditions on landscapes within reserves, for example, and using extended cutting cycles and restorative forestry practices in working forests.”
The authors found that forests’ climate resiliency increased with age; older forests are more structurally-complex, they explain, with trees growing at multiple heights and larger canopy gaps, which free up growing space and increase light availability for a mix of species. Scientists usually count forests as ‘old’ over the age of around 150 years.
“This research presents new and entirely novel findings that are sure to push the needle in our understanding of forest dynamics,” says Keeton.
The types of ecosystem services and biodiversity provided on forested landscapes today are likely to change dramatically into the future, both as forests age and our climate changes — a message relevant to anyone interested in forests.
The paper “The climate sensitivity of carbon, timber, and species richness covaries with forest age in boreal–temperate North America” has been published in the journal Global Change Biology.