During the 2024-25 legislative session, Senator Bob Smith, chair of the N.J. Senate Environment and Energy Committee is expected to conduct hearings on a bill concerning forest stewardship for publicly owned lands, a controversial issue that Senator Smith has seen as necessary to legislate for at least 10 years.  For this legislation to achieve its purpose—to protect the state’s forests for future generations—the state must embrace the science that mature, high integrity forests left in their natural state provide the most public benefits.  Forests left to mature steadily on their own accumulate more carbon, provide for a clean water supply and provide habitat for diverse wildlife and human refuge.   

Unfortunately, this view conflicts with the position of many in the traditional forestry community and a minority of environmentalists who believe forests need constant intervention, and that logging-as-management creates a better forest.  

The latest research supports the position that mature, natural forests are the best for climate stabilization and the overall environment.  Professor Sara Webb, a distinguished forest scientist and Highlands Coalition trustee, has assembled a set of recent scientific papers which review the various benefits of natural forests, from the superiority of mature forests as carbon sinks, to the well-established understanding that mature forests are the most protective of our drinking water resources. 

As the NJ Senate engages in its work this year, we urge legislators and all interested parties to review these papers and lend their support to natural forests. The problem is especially acute in New Jersey, as Professor Webb observes:

Most of the state’s woodlands, private and public, are dominated by invasive non-native vegetation.  And, unfortunately, reproduction by native trees is rarely seen because of deer and invasive species.…Thus, when forests are logged and thinned, new trees will not sprout in openings and a new generation of forest will not return….

Dr. Webb summarizes the latest scientific findings we have compiled here and makes a concise argument for allowing the most mature, least fragmented forests of New Jersey, notably the 320 square-mile Highlands Core Forest, to be allowed to follow their natural trajectory into old-growth by limiting interventions except when absolutely necessary and by using the least harmful approach. 

Essay:
Importance of Natural Forests and Older Trees to both Climate Defense and Biodiversity: Evidence from Scientific Research

Sara Webb, PhD.,
Professor emerita of Biology
Drew University, Madison, NJ
swebb@drew.edu 

Established natural forests are uncommon but invaluable in densely populated New Jersey:  vital for climate resilience, for biodiversity, and for public water quality and supply.  Most woodlands, both private and public, are dominated by invasive non-native vegetation, and reproduction by native trees is rare.  Except in the pinelands, forests of native trees are rare in a matrix of New Jersey development, but they will not return after logging (by any name).    

Yet for most public conservation lands of New Jersey, including state forests and wildlife management areas, today’s policies and practice are to harvest or clear the most mature natural forests, logging out large swaths and removing the wood. In some state Wildlife Management Areas such as Sparta Mountain, plans are to log most of the preserve, one section each year. This creates openings with the goal of more young forests at the expense of old.  But the forest does not regrow. The scale and extent of clearing the canopy could be appropriate for production of wood products and to build deer populations, but is very destructive for biodiversity and climate defense, as scientific research has shown (see references below).  

There are major problems with this approach:
(1) It does not work.  A new generation of small native trees will not move in, least of all the oaks that land managers hope to reestablish (Kellett et al. 2023; Luyssaert et al. 2008).   Though promoted as the young forest initiative, this effort to establish more young forest simply will not succeed in northern and central New Jersey (nor in many other regions). This is because clearings are heavily browsed by overabundant deer and are taken over by invasive species. 

Forest fails to come back without very costly and ongoing interventions: long-term use of herbicides and well-maintained 8-10’ perimeter fencing.  We know this because the New Jersey landscape has plenty of openings and extensive edges already, which fill with invasive vegetation with little if any return of oaks or other native trees.  Only within deer-excluding fencing in other public and private forests does a future forest get established.  In a matrix of New Jersey development, today’s natural forests are not common, and they will not return after logging.    

(2) Climate change defense is impaired, not improved, an important consideration.  Clearing of mature forests not only sacrifices biodiversity into the future but also forfeits the extraordinary climate-change defense provided by larger, mature trees, which take up and sequester by far the most carbon, stored in their biomass and across the forest.  (Luyssaert et al 2008. Midrexler et al. 2020; Pugh et al 2019Maxwell et al, 2019; Law et al. 2022).   

Mature natural forests, like large individual trees, provide by far the most carbon sequestration.  The clearing of established forest to create early-successional habitat, common in New Jersey today, is often tallied as climate defense.  This is misleading at best. This connection could be true if an acre of young forest both absorbed and stored more carbon than an acre of mature forest.   However, science shows that, on the contrary, intact forest canopies and mature forests provide the best and indeed essential defense against climate change, storing and taking up the most carbon per acre in proportion, to leaf area and biomass (Law et al. 2022).  The best approach, known as proforestation, is the practice of protecting instead of harvesting a forest for carbon defense (Moomaw et al. 2019) .

(3) After harvest when wood is used for construction, we might expect its carbon to be stored and kept out of the atmosphere long-term.  This misconception is often applied in greenhouse gas calculations and leads to counting as carbon storage that which is put into in wood products and landfills after removal from the forest.  Research by Ingerson (2011) and others follows the fate of carbon through wood harvesting, processing, transport, use, waste, and disposal, and decomposition. Analyzing how much carbon and climate defense is lost reveals that carbon storage in wood products is surprisingly brief.   One hundred years post-harvest, only an estimated 1% will remain in products in use and 13% will be in landfills.   Ultimately the amount of carbon stored long-term in harvested wood products is a small proportion of that originally stored in the standing trees across the United States.  Policies that promote wood product carbon storage as a climate mitigation strategy must assess full life-cycle impacts, address accounting uncertainties, and balance multiple public values derived from forests.

(3) Further exacerbating the loss of climate defense, the logging of natural forest types of north/central New Jersey also fragments a major migration corridor for species whose habitat is shifting northward, blocking native trees and their inhabitants, putting all in peril.  (see projections by Gardner et al. 2017,  and the Nature Conservancy’s Resilient Land Mapping Tool:  https://maps.tnc.org/resilientland/).  

08/09/2024
(All sources cited below):

The most recent science is saying:

Creating young forests in mature forests degrades forest health:
Kellett MJ, Maloof JE, Masino SA, Frelich LE, Faison EK, Brosi SL and Foster DR (2023). Forest clearing to create early successional habitats: Questionable benefits, significant costs

Mature trees sequester more carbon annually than young trees and undisturbed forest soils sequester more carbon than disturbed soil:
Leverett, Robert T. 2023. Carbon sequestered and stored in young versus old forests in the Adirondacks

Current strategies to reduce wildfire risks degrade forest health:
Law BE et al. 2022. Creating strategic reserves to protect forest carbon and reduce biodiversity losses in the United States

Old forests continue to store vast amounts of carbon in trees and soils:
Anderson MG. 2021. Wild carbon: a synthesis of recent findings

Large-diameter trees store disproportionally massive amounts of carbon and are a major driver of carbon cycle dynamics in forests worldwide:
Midrexler DJ et al. 2020.  Large trees dominate carbon storage in forests east of the cascade crest

Deer and invasive have seriously degraded New Jersey forest health:
Kelly, JF. 2019.  Regional changes to forest understories since the mid-Twentieth Century:  Effects of overabundant deer and other factors in northern New Jersey

Protecting mature forests in their natural state provides the greatest defense against climate change and the greatest benefit to the overall environment :
Moomaw WR, Masino SA, Faison EK. 2019. Intact Forests in the United States: Proforestation Mitigates Climate Change and Serves the Greatest Good

Second growth forests allowed to mature provides great potential for establishing renewed carbon sinks:
Pugh  TA et al.  2019.  Role of forest regrowth in global carbon sink dynamics  PNAS 116(10):4382-4387.

Intact tropical forests sequester large amounts of carbon; their loss and degradation increases climate harm per acre by 626%.
Maxwell SL, Evans T, Watson JEC, Morel A, Grantham H, Duncan A, Harris N, Potapov P, Runting RK, Venter O, Wang S, Malhi Y. 2019. Degradation and Forgone Removals Increase the Carbon Impact of Intact Forest Loss by 626% 

Invasive species continue to hinder the healthy development of natural forests:
Ritters et al. 2018.  Exposure of Protected and Unprotected Forest to Plant Invasions in the Eastern United States 

Large-diameter trees store by far the most carbon per tree and per acre while conserving and enhancing ecosystems:
Lutz, J. A. et al.  2018. Global importance of large-diameter trees Global Ecology and Biogeography 27(7): 849-864.

Loss of trees in the interior forests contribute to significant declines in forest bird species:
Gardner TJ, Eagan CR, Robert RI   2017. Forest Bird Populations in Massachusetts: Breeding Habitat Loss and Other Influences

Mature trees, in addition to continuing to sequester more carbon as they grow, share carbon with other species in the forest:
Klein, T et al. 2016. Below ground carbon trade among tall trees in a temperate forests

Forest fragmentation reduces the ability of forests to provide important natural services for biodiversity and climate defense:
Haddad NM, et al. 2015. Habitat Fragmentation and Its Lasting Impact on Earth’s Ecosystems

Carbon accumulation, rather than leveling off with age, increases exponentially with tree size:
Stephensen NL et al. 2014. Rate of Tree Carbon Accumulation Increases Continuously with Tree Size

It is a myth that harvested wood is a significant contributor to carbon storage:
Ingerson, A. 2011. Carbon storage potential of harvested wood: summary and policy implications

There is no clear connection between establishing young forests and repopulating declining species:
Lorimer CG, White AS. 2003. Scale and frequency of natural disturbance in the northeastern US: implications for early successional forest habitats and regional age distributions. Forest Ecology and Management 185:41-64.

Mature forests store carbon at superior rates and are among the most powerful carbon sinks on the planet, exponentially more than young forests:
Luyssaert S, et al. 2008.  Old-growth forests as global carbon sinks

 Conversion of old growth forests to young stands provides no benefit to carbon storage, releases enormous volumes of climate-warming carbon to the atmosphere and requires a minimum of 200 years to restore the forests’ ability to serve as a carbon sink:
Harmon ME, Ferrell WK, Franklin JF. 1990. Effects on carbon storage of conversion of old-growth forests to young forests