Carbon, Climate Change, & Forests
Climate change and forests are related in many ways. Climate change compromises the health and function of the forest ecosystem. However, forests can reduce the rate and scale of climate change and mitigate its negative impacts.
Forests are a critical component of the global carbon cycle. They are dynamic systems, constantly absorbing and releasing carbon dioxide. Carbon is removed from the atmosphere through the process of sequestration, which uses carbon for photosynthesis. This supports and maintains plant growth. Generally, carbon sequestration rates are greater in younger (20-70 year old) forests, where the growth of species is maximized following reforestation, or regeneration after a natural or human disturbance.
Carbon resides in forests in different places for different amounts of time. A carbon pool is a part of the forest that stores carbon. The amount of carbon stored in any one pool changes over time. Forest carbon pools are live aboveground vegetation, live belowground vegetation, deadwood, litter (leaves, needles, twigs), and soil organic matter. Carbon is also stored in wood products. This is an important carbon pool, as the use of durable wood products, particularly those derived from local or regional harvests, reduces carbon emissions associated with carbon-intensive materials such as concrete, steel, and plastics.
Carbon storage is the amount of carbon retained in a particular pool. The amount of carbon stored at any given time is influenced by several factors. Generally, carbon storage is greater in older forests and structurally complex forests.
Forests help to slow the rate of climate change by removing carbon dioxide from the atmosphere and storing it. This is a direct effect, as the primary driver of climate change is the over-abundance of carbon dioxide in the atmosphere. Forests also provide indirect effects which lessen the impacts of climate change on society.
Forest management practices can be tailored to improve forest health and biodiversity, resilience, and adaptability. Reducing harvest frequency and favoring high levels of structural retention, for example, can sequester up to 57% more carbon in northern hardwood-conifer forests (Nunery and Keeton 2010). Managing forests for structural complexity in mixed northern hardwood forests of eastern North America has been found to increase elements of late-successional biodiversity (Dove and Keeton 2015; Gottesman and Keeton 2017; McKenny et al. 2006) and carbon storage (Ford and Keeton 2017) while, at the same time, providing wood products from timber harvests (Nunery and Keeton 2010).
In sum, forest management provides an opportunity to transfer carbon stored in live trees into durable wood products. It simultaneously creates favorable conditions for the removal of additional carbon dioxide from the atmosphere.
For every one cubic foot of wood harvested from Connecticut forests, over six cubic feet of wood grows.
For every one cubic foot of wood harvested from Massachusetts forests, over five cubic feet of wood grows.
For every one cubic foot of wood harvested from Rhode Island forests, about six cubic feet of wood grows.
Harvested wood products throughout the US, a byproduct of forest management, remove approximately 103 MMT CO2 eq., while conversion of forest land to non-forest land emits over 126 MMT CO2 eq. to the atmosphere (Domke et al. 2019).
The carbon in durable wood products is stored much longer than the carbon in dead trees (Russell 2014). In southern New England, the volume of wood in trees that die naturally is over three times that contained in harvested trees (Oswalt et al. 2019).
Domke, Grant M.; Walters, Brian F.; Nowak, David J.; Smith, James, E.; Ogle, Stephen M.; Coulston, John W. 2019. Greenhouse gas emissions and removals from forest land and urban trees in the United States, 1990-2017.Resource Update FS-178. Newtown Square, PA: U.S. Department of Agriculture, Forest Service, Northern Research Station. 4 p. https://doi.org/10.2737/FS-RU-178.
Dove, N.C., Keeton, W.S., 2015. Structural Complexity Enhancement increases fungal species richness in northern hardwood forests. Fungal Ecol. 13, 181–192. https://doi.org/10.1016/j.funeco.2014.09.009.
Nunery, J.S. and Keeton, W.S. (2010) Forest carbon storage in the northeastern United States: Net effects of harvesting frequency, post-harvest retention, and wood products. Forest Ecology and Management 259(8): 1363-1375.
McKenny, H.C., Keeton, W.S., Donovan, T.M., 2006. Effects of structural complexity enhancement on eastern red-backed salamander (Plethodon cinereus) populations in northern hardwood forests. For. Ecol. Manage. 230, 186–196. https://doi.org/10.
Oswalt S.N., Smith W.B., Miles P.D., and Pugh S.A. (2018) Forest Resources of the United States, 2017: A technical document supporting the Forest Service 2020 RPA Assessment. Gen. Tech. Rep. WO97. Washington, DC: U.S. Department of Agriculture, Forest Service, Washington Office. 237 pp.
Russell, M.B., Woodall C.W., Fraver S., D’Amato A.W., Domke G.M., and Skog K.E. (2014). Residence times and decay rates of downed woody debris biomass/carbon in the Eastern United States. Ecosystems 17:765-777.