Older Eastern White Pine Trees and Stands Accumulate Carbon for Many Decades and Maximize Cumulative Carbon

Abstract

Pre-settlement New England was heavily forested, with trees exceeding 2 m in diameter. The forests have regrown since farm abandonment, representing what is arguably the most successful regional reforestation on record and identified recently in the “Global Safety Net.” Temperate “old-growth” forest and remnant stands demonstrate that native tree species can live several hundred years and continue to add to forest biomass and structural and ecological complexity. Forests globally are an essential natural climate solution that accumulate carbon and reduce annual increases in atmospheric CO2 by approximately 30%. Some studies emphasize young, fast-growing trees and forests while others highlight carbon storage and accumulation in old trees and intact forests. We addressed this directly within New England with long-term, accurate field measurements and volume modeling of individual trees and two stands of eastern white pines (Pinaceae: Pinus strobus) and compared our results to models developed by the U.S. Forest Service. Within this sample and species, our major findings complement and clarify previous findings and are threefold: (1) beyond 80 years, an intact eastern white pine forest can accumulate carbon above-ground in living trees at a high rate and double the carbon stored in this compartment in subsequent years; (2) large trees dominate above-ground carbon and can continue to accumulate carbon; (3) productive stands can continue to accumulate high amounts of carbon in live trees for well over 150 years. Because the next decades are critical in addressing the climate emergency, and most New England forests are less than 100 years old, a major implication of this work is that maintaining and accumulating carbon in some existing forests—proforestation—is a powerful regional climate solution. Furthermore, older and old-growth trees and forests are rare, complex, highly dynamic and biodiverse: dedication of some forests to proforestation will produce large carbon-dense trees and also protect ecosystem integrity, special habitats, and native biodiversity long-term. In sum, strategic policies to grow and protect suitable existing forests in New England will optimize a proven, low cost, natural climate solution that also protects and restores biodiversity across the landscape.

Forest-clearing to create early-successional habitats: Questionable benefits, significant costs

“…The term "even-aged" can evoke images of a tree farm or a plantation, but natural forests do not have such a uniform structure, particularly those older than 60-80 years. Although 60-80 year old trees may be termed "mature, " or almost "overmature, " they are at far less than half their natural lifespan and likely at far less than 20% of their potential carbon accumulation (Thompson et al, 2009;Leverett et al, 2021). Most important, forests that are relatively even-aged will transition on naturally toward old-growth and uneven-aged condition if simply left alone (Gunn et al, 2014;Catanzaro and D'Amato, 2019).…”

“…Some studies suggest that younger forests between 30 and 70 years (Catanzaro and D'Amato, 2019) or 40-80 years (Leverett et al, 2021) can sequester carbon at a faster rate than mature or old-growth forests. Other analyses indicate that lands reserved from logging in the Northeast have net carbon sequestration rates that are roughly 33% higher than in logged forests and are projected to sequester more carbon over the next 150 years (Brown et al, 2018).…”

“…Nevertheless, the climate mitigation value of forest carbon lies not in the sequestration rate but in the total amount that is accumulated and kept out of the atmosphere (Mackey et al, 2013). The power of forests in this process is unparalleled and far greater in old forests than in young forests, both above and below ground; carbon continues to accumulate for centuries (Zhou et al, 2006;Luyssaert et al, 2008;Keeton et al, 2011;Curtis and Gough, 2018;Leverett et al, 2021;Law et al, 2022).…”

Capitalizing Trees for Carbon Sequestration as a Co-Benefit of Biophilic Urbanism

“…The age and height of a tree have shown a moderately good relationship and a considerable impact on CS. Leverett et al [47] reported that large trees had dominance in accumulating carbon and aged trees had a high accumulation rate of carbon. Matured and aged trees showed high values for CS along with the R 2 0 .99 for basal area and 0.60 for height [48].…”

A Reevaluation of Superior Tree Performance After 48 Years for a Loblolly Pine Progeny Test in Southern Arkansas

“…Furthermore, some outputs (e.g., specialty products, such as poles or pilings, or maximizing carbon to be sequestered under contracts) may not be optimized by families selected for maximal early volume growth and short rotations. As an example, a growing body of evidence suggests significant carbon accumulation in older trees and stands that could alter strategies (much longer rotations) for using forests to sequester atmospheric carbon dioxide (e.g., Carey et al, 2001;Luyssaert et al, 2008;Stephenson et al, 2014;Sillett et al, 2019;Leverett et al, 2021).…”