Forest Carbon
Forest Carbon
Forests are one of the most important components of the global carbon cycle. Through photosynthesis, trees remove carbon dioxide from the atmosphere and store carbon in trunks, branches, leaves, roots, dead wood, litter, and soils. At the same time, forests release carbon through respiration, decomposition, wildfire, tree mortality, harvesting, and land-use change. Whether a forest acts as a carbon sink or a carbon source therefore depends on the balance between carbon uptake and carbon loss.
Research across several decades shows that the world's forests collectively remain an important carbon sink. Established forests, recovering forests, and expanding forest areas remove substantial amounts of carbon dioxide from the atmosphere. This contribution, however, is not uniform across regions and is increasingly threatened by deforestation, degradation, wildfire, drought, rising temperatures, and other disturbances.
Forest carbon is consequently more complex than simply counting trees. The amount of carbon a forest stores depends on forest age, tree size, species composition, soils, climate, disturbance history, management practices, and what happens to wood after harvesting. Understanding forest carbon requires examining entire ecosystems over long periods rather than focusing exclusively on annual tree growth.
The Global Forest Carbon Sink
Forests have absorbed a substantial share of human-generated carbon dioxide emissions for decades, reducing the amount of carbon that remains in the atmosphere. Both established forests and forests recovering after previous clearing or disturbance contribute to this global sink.
The strength of the sink varies considerably among regions. Forest expansion, reforestation, changing management, atmospheric carbon dioxide, nutrient availability, climate, and forest age all influence carbon accumulation. Some countries and regions have experienced increasing forest carbon stocks, while others have lost carbon because of deforestation, degradation, wildfire, or increasing tree mortality.
Recent research also indicates that the global forest sink cannot automatically be assumed to remain stable. Severe fires and continuing deforestation have weakened forest carbon uptake in recent years. Climate change may further alter tree growth, mortality, decomposition, soil processes, and nutrient cycling.
Forests therefore provide an important climate benefit, but that benefit depends on maintaining the ecological conditions that allow forests to continue accumulating and retaining carbon.
Tropical Forests and Regional Carbon Dynamics
Tropical forests contain enormous amounts of carbon and historically have played a major role in absorbing atmospheric carbon dioxide. Yet their future contribution is increasingly uncertain.
Long-term observations in the Amazon have documented weakening carbon uptake associated partly with increasing tree mortality. Research comparing intact Amazonian and African tropical forests also suggests that some tropical carbon sinks may be approaching saturation, although the timing and severity vary geographically.
Deforestation and forest degradation add another problem. A tropical region can contain rapidly growing forests while still becoming a net carbon source if clearing, logging, fire, and degradation release more carbon than surviving and regenerating forests absorb.
Climate extremes can further alter this balance. Severe drought may cause tree mortality and biomass loss whose effects continue for years after rainfall returns. Tropical forests therefore cannot be treated as a single uniform carbon reservoir. The Amazon, Congo Basin, Southeast Asian forests, tropical montane forests, and other regions differ substantially in climate, soils, disturbance, management, and carbon dynamics.
Mature Forests, Old-Growth Forests, and Large Trees
Forest age has major implications for carbon storage. Young forests can accumulate carbon rapidly because trees are growing quickly, but mature and old forests often contain far larger accumulated carbon stocks.
Large trees are particularly important. Studies across many forest types show that large trees account for a disproportionate share of aboveground biomass and can continue adding substantial amounts of carbon as they grow. Losing a small number of very large trees can therefore release or remove a large amount of stored carbon.
Research has challenged the older assumption that mature forests necessarily become carbon neutral. Many mature forests continue accumulating carbon, although the rate differs among ecosystems and some estimates of old-growth sequestration have been debated or revised.
Replacing an old forest with a young forest may eventually produce rapid growth, but the initial loss of accumulated biomass can create a substantial carbon deficit. Carbon policy must therefore distinguish between the rate at which carbon is being absorbed and the total quantity of carbon already stored in an ecosystem.
Forest Soils, Roots, and Dead Wood
A large portion of forest carbon exists outside living tree trunks. Forest soils, roots, litter, dead wood, and other belowground and decomposing material can contain enormous carbon reserves.
Soil carbon is influenced by climate, vegetation, fungi, roots, soil chemistry, forest age, disturbance, and management. Tree roots both stimulate decomposition and contribute new organic material that may eventually become stabilized in soils. Fungal communities and mycorrhizal relationships can also influence how carbon moves through forest ecosystems.
Harvesting can reduce soil carbon, particularly when logging residues, forest-floor material, or whole trees are removed intensively. Effects vary according to soil type, harvesting method, climate, and ecosystem.
Dead wood represents another significant carbon pool. Carbon remains stored in dead trees until decomposition or combustion returns it to the atmosphere. Climate-driven changes in tree mortality and decomposition can therefore alter the rate at which forests retain or release carbon.
Forest carbon accounting that measures only living aboveground trees consequently captures only part of the ecosystem carbon balance.
Biodiversity, Forest Structure, and Carbon Storage
Carbon storage is closely connected to forest structure and ecological composition. Large trees, vertical complexity, tree density, species composition, functional traits, soils, and environmental conditions all influence how much carbon forests can hold.
More diverse forests can sometimes provide both carbon and biodiversity benefits. Mixed-species plantings may improve ecological resilience and can increase soil carbon or make carbon sequestration more reliable under some conditions. However, biodiversity and carbon objectives are not always identical. A management system designed purely to maximize carbon may not maximize habitat quality or species diversity.
Fragmentation is another important factor. Forest edges often contain less biomass than comparable forest interiors because of altered temperature, moisture, wind exposure, mortality, and disturbance. A landscape can therefore retain apparent forest cover while losing ecological integrity and carbon.
Forest conservation policies are strongest when carbon storage is considered alongside biodiversity, ecosystem resilience, water, soils, and habitat rather than as an isolated objective.
Wildfire, Drought, Mortality, and Climate Change
Disturbance is one of the greatest uncertainties surrounding future forest carbon storage.
Wildfires release carbon directly through combustion and indirectly through tree mortality and subsequent decomposition. In some boreal forests, increasingly severe fires can burn deep organic soils and release carbon that has remained stored for centuries.
Drought can reduce tree growth, increase mortality, intensify wildfire risk, and prolong forest recovery. Drought and fire can also interact, creating losses larger than either disturbance might produce independently.
Climate change complicates these processes. Warming can accelerate decomposition, change nutrient cycling, alter species distributions, increase atmospheric moisture demand, and expose forests to combinations of heat, drought, insects, disease, storms, and fire.
Some management treatments, including thinning and prescribed burning, intentionally remove or release carbon in the short term to reduce the risk of catastrophic future wildfire. Whether these treatments improve the long-term carbon balance depends heavily on forest type, fire regime, treatment intensity, and the probability of severe disturbance.
The climate value of forest carbon therefore depends not simply on how much carbon is stored today, but on how securely that carbon can remain stored in a changing climate.
Forest Management and Harvesting
Forest management can substantially change both carbon stocks and carbon sequestration rates.
Harvesting generally reduces standing forest carbon immediately because biomass is removed from the ecosystem. Forests may later regrow and begin accumulating carbon again, but the recovery period can extend for decades. The outcome depends on harvest intensity, rotation length, forest type, soil disturbance, post-harvest regeneration, and the fate of harvested wood.
Thinning illustrates the complexity. Removing trees reduces standing biomass in the short term but can sometimes increase the growth of remaining vegetation or alter soil processes. Results differ among ecosystems, and no single management prescription maximizes carbon everywhere.
Reduced-impact logging, continuous-cover forestry, longer rotations, protection of large trees, restoration treatments, and climate-smart forestry have all been investigated as methods for balancing carbon storage with timber production and ecosystem resilience.
The central trade-off is often between maximizing carbon already stored in forests and maximizing rates of new tree growth or wood production. These are related objectives, but they are not the same.
Reforestation, Natural Regeneration, and Forest Restoration
Restoring forests can remove substantial amounts of carbon dioxide from the atmosphere while also rebuilding habitat and ecosystem functions.
Natural regeneration is particularly important. When previously forested land is allowed to recover, trees can return without intensive planting, and young secondary forests can accumulate carbon rapidly. Assisted natural regeneration can accelerate this process by reducing grazing, repeated clearing, fire, invasive vegetation, or other barriers to recovery.
Plantations can also accumulate carbon, but their climate and biodiversity effects depend on where they are established, which species are planted, how frequently they are harvested, and what ecosystem existed beforehand. Planting trees is not automatically beneficial if it replaces natural grasslands, peatlands, or other carbon-rich ecosystems.
Reforestation also differs from afforestation. Restoring a previously forested landscape may recover part of a lost ecosystem, whereas creating tree cover on land that was naturally non-forest can produce very different ecological consequences.
Protecting existing natural forests and allowing cleared forests to regenerate are therefore complementary strategies. Restoration should not become a justification for continued destruction of mature forests whose accumulated carbon could take decades or centuries to replace.
Measuring Forest Carbon
Accurate forest carbon policy requires accurate measurement.
Traditional forest inventories use permanent field plots to measure tree diameter, height, species, growth, mortality, harvesting, and other characteristics. Scientists then use biomass equations to estimate the carbon contained in trees and forest ecosystems.
Satellite observations have greatly expanded the ability to monitor forests globally. Lidar instruments such as GEDI can measure forest height and vertical structure, while optical, radar, and other remote-sensing systems help map forest cover, biomass, disturbance, and recovery.
New measurement techniques reveal substantial geographic variation in forest carbon. They also demonstrate that estimates depend on the models, biomass equations, spatial scale, and data sources being used.
Measurement uncertainty becomes particularly important for carbon-credit projects. An estimate that performs adequately over a continent or country may not provide the same accuracy when applied to a small individual project.
Improving forest carbon monitoring therefore requires combining field observations, satellites, ecosystem models, national inventories, and transparent statistical methods.
Harvested Wood Products and Carbon Accounting
Carbon removed during timber harvesting does not necessarily enter the atmosphere immediately. Some remains stored in buildings, furniture, other products, or landfills for years or decades.
This has led to proposals that harvested wood products can contribute to climate mitigation. Longer-lived products generally retain carbon longer than paper, fuel, or other short-lived uses.
However, harvested wood accounting is complicated. The carbon stored in products must be considered alongside carbon removed from forests, emissions from harvesting and processing, decomposition, disposal, forest regrowth, and the carbon that could have remained stored if trees had not been harvested.
Claims that wood automatically provides large climate benefits by replacing concrete, steel, fossil fuels, or other materials are also disputed. Substitution benefits depend on the emissions of alternative materials, future energy systems, product lifetimes, recycling, forest regrowth, and the time period being analyzed.
The climate consequences of harvesting therefore require whole-system and long-term accounting rather than simply counting carbon contained in wood products.
Peat-Swamp Forests and Mangroves
Some forests contain exceptionally large belowground carbon stocks.
Tropical peat-swamp forests can accumulate thick deposits of organic material over thousands of years. Drainage, agricultural conversion, logging, and fire expose this stored carbon to oxidation and combustion, potentially producing large and persistent emissions.
Mangrove forests similarly store substantial quantities of carbon in waterlogged soils as well as vegetation. Because decomposition is slow in saturated sediments, mangrove soils can retain carbon for long periods.
Protecting and restoring peat-swamp forests and mangroves can therefore prevent major emissions while also supporting biodiversity, fisheries, coastal protection, and other ecosystem services.
These ecosystems also demonstrate why forest carbon cannot be judged by tree biomass alone. In peatlands and mangroves, some of the most important carbon is underground.
REDD+, Forest Carbon Credits, and Accounting Integrity
Forest carbon has become an important component of climate policy and voluntary and regulated carbon markets.
REDD+ seeks to create incentives for reducing emissions from deforestation and forest degradation while supporting conservation, sustainable forest management, and enhancement of forest carbon stocks. Programs operate at project, jurisdictional, and national scales.
The fundamental challenge is determining whether credited carbon benefits are real and additional. A project should not receive credits for forest protection that would probably have occurred without the project. Establishing credible baselines is therefore essential.
Studies of forest offset programs have identified cases of over-crediting caused by unrealistic baselines or other methodological problems. Permanence is another concern. Carbon credited today may later be released through wildfire, drought, logging, disease, or land-use change.
Leakage must also be considered. Protecting one forest provides less climate benefit if logging or land clearing simply shifts somewhere else.
Effective forest carbon programs consequently require credible baselines, additionality, long-term monitoring, safeguards against reversal, transparent accounting, and attention to governance, land tenure, livelihoods, biodiversity, and local communities.
Forest carbon credits can potentially support conservation, but they are not equivalent to eliminating fossil-fuel emissions. Fossil carbon transferred from geological storage to the atmosphere adds carbon to the active carbon cycle, while forest carbon remains biologically stored and vulnerable to future release.
Conclusion
Forests are a major part of the Earth's carbon system and an important natural defense against climate change. Existing forests store enormous quantities of carbon, while growing and regenerating forests continue removing carbon dioxide from the atmosphere.
Their climate value extends far beyond the annual growth of trees. Mature forests, large trees, soils, roots, dead wood, peat deposits, and mangrove sediments all contribute to carbon storage. Biodiversity and structural complexity can influence both carbon stocks and ecosystem resilience.
At the same time, forest carbon is not permanent or guaranteed. Deforestation, logging, wildfire, drought, degradation, fragmentation, and climate-driven mortality can rapidly reverse decades of carbon accumulation. Management and restoration can improve outcomes, but their effects vary by ecosystem and must be evaluated over long periods.
The evidence therefore supports a hierarchy of complementary strategies: protect carbon-rich existing forests, reduce deforestation and degradation, improve management where forests are harvested, protect soils and other belowground carbon pools, allow natural forests to regenerate, restore degraded forests where ecologically appropriate, and improve measurement and carbon-accounting standards.
Forest restoration and carbon markets can contribute to climate mitigation, but they cannot substitute for protecting existing ecosystems or rapidly reducing fossil-fuel emissions. The strongest forest-carbon strategy is one that treats forests not merely as collections of carbon units but as complex, living ecosystems whose carbon storage depends on biodiversity, climate resilience, soils, disturbance regimes, and long-term stewardship.
Global Forest Carbon Sinks and the Carbon Cycle
Reconstructs roughly 150 years of French forest change and evaluates how management, forest expansion, growth, and environmental change created a persistent national carbon sink.
Investigates interactions among forest carbon sequestration, economic development, and emissions in China and highlights tensions between forest gains and broader economic emissions.
Estimates the quantity and economic cost of additional forest-based carbon mitigation across more than 200 countries.
Uses Forest Resources Assessment and FAOSTAT data to quantify forest carbon removals, forest-conversion emissions, and regional trends for countries worldwide.
Examines how severe fires and continuing deforestation sharply weakened the global forest carbon sink during 2023 and 2024.
Models how warming alters forest carbon and nitrogen cycling and finds geographically unequal effects on future forest carbon storage and economic forest assets.
The enduring world forest carbon sink | Yude Pan et al. | Nature | 2024-07-17
Assesses the global forest carbon sink over several decades, showing that forests continue to absorb substantial amounts of atmospheric carbon despite increasing disturbances and regional changes.
Examines how elevated atmospheric carbon dioxide affects forest productivity, nitrogen fixation, nutrient-use efficiency, and future carbon-sink capacity.
Combines spaceborne lidar with ecosystem modeling to reveal large geographic differences in forest biomass, carbon stocks, and carbon fluxes.
Maps carbon emissions and removals from forests worldwide, revealing major differences among intact forests, managed forests, deforestation zones, and regions undergoing forest recovery.
Shows that nutrient availability strongly influences whether forests channel productivity into long-term carbon storage or rapidly recycle carbon through ecosystems.
Introduces forest sequestration, carbon pools, management options, and carbon-offset opportunities and risks for forests in the southern United States.
A Large and Persistent Carbon Sink in the World's Forests | Yude Pan et al. | Science | 2011-07-14
Provides a landmark global assessment showing that established and regrowing forests constitute a major terrestrial carbon sink while tropical deforestation remains an important source of emissions.
Reviews afforestation, avoided deforestation, forest management, wood products, biomass energy, disturbance risk, and other strategies affecting U.S. forest-sector carbon.
Old-growth forests as global carbon sinks | Sebastiaan Luyssaert et al. | Nature | 2008-09-11
Challenges the assumption that old forests become carbon neutral, finding that many continue accumulating carbon for centuries.
Tropical and Regional Forest Carbon Dynamics
Distinguishes different forms of tropical forest regrowth and finds that naturally expanding forest can make a particularly important contribution to carbon accumulation.
Reviews and analyzes how climate change, atmospheric carbon dioxide, land-use change, and other pressures may reshape the Congo Basin carbon cycle.
Examines how tropical forests across South America responded to extreme climatic conditions and identifies variation in carbon sensitivity among forest regions.
Shows how afforestation increased carbon stocks in parts of the Greater Mekong while deforestation caused substantial carbon losses elsewhere.
Maps potential additional terrestrial carbon storage while emphasizing the importance of protecting existing ecosystems and avoiding inappropriate land conversion.
Explains global forest carbon-flux mapping showing how standing and regrowing forests remove carbon while deforestation and degradation generate emissions.
Finds that intact tropical forests in Africa and Amazonia are showing signs of carbon-sink saturation, with the Amazon sink weakening earlier and more rapidly.
Demonstrates the use of high-resolution commercial satellite imagery to monitor tropical forest biomass, carbon stocks, and emissions.
Uses lidar observations to identify persistent Amazon biomass losses following the severe 2005 drought and demonstrates the long carbon legacy of extreme drought.
The tropical forest carbon cycle and climate change | Edward T. A. Mitchard | Nature | 2018-07-25
Reviews observations and models of tropical forest carbon stocks, productivity, deforestation, degradation, and the uncertain response of tropical forests to climate change.
Uses satellite observations to show that tropical forest carbon losses from deforestation and degradation can exceed gains from forest growth.
Long-term decline of the Amazon carbon sink | R. J. W. Brienen et al. | Nature | 2015-03-18
Uses long-term measurements from hundreds of Amazon forest plots to document declining biomass accumulation as increased tree mortality weakens the Amazon carbon sink.
Produces a benchmark map of tropical forest carbon stocks across Latin America, Africa, and Asia using satellite and field observations.
Demonstrates high-resolution mapping of Amazon forest carbon stocks and emissions, improving spatial understanding of where carbon is stored and lost.
The Role of Forests in the Global Carbon Budget | FAO | State of the World's Forests | 2001
Provides an accessible overview of carbon stored in forest vegetation, dead biomass, soils, and forest products and explains differences among major forest biomes.
Forest Age, Mature Forests, and Large Trees
Uses extensive GEDI observations to show that drought, aridity, storms, soils, and topography influence tropical forest biomass differently among regions.
Finds widespread carbon accumulation in mature forests that conventional satellite approaches can underestimate, reinforcing the continuing carbon importance of established forests.
Shows that replacing old forests with young stands can temporarily accelerate uptake while producing substantial losses of accumulated aboveground carbon.
Reports a shift in Australian tropical forest aboveground biomass from long-term carbon accumulation toward net carbon loss as tree mortality increases.
Finds that increases in global live biomass carbon during the 2010s were driven largely by young and middle-aged forests in northern regions.
Finds unexpectedly high aboveground carbon stocks in African tropical montane forests and highlights the climate value of protecting these comparatively limited ecosystems.
Old-growth forest carbon sinks overestimated | Per Gundersen et al. | Nature | 2021-03-24
Reassesses estimates of carbon accumulation in very old forests and argues that some previously reported sink rates were substantially overestimated.
Demonstrates across hundreds of tree species that individual large trees generally accumulate more carbon each year than smaller trees.
Shows that variation in the abundance and size of large trees explains much of the difference in aboveground biomass among tropical forests.
Carbon accumulation in European forests | Philippe Ciais et al. | Nature Geoscience | 2008-06-22
Examines European forest carbon accumulation and the combined influence of changing management, forest age, climate, atmospheric carbon dioxide, and nitrogen deposition.
Forest Structure, Biodiversity, and Carbon
Models European forest management strategies and finds that maximizing carbon storage and maximizing biodiversity do not always produce the same management choices.
Synthesizes studies showing that mixed-species plantations can improve soil aggregation and promote soil carbon storage compared with monocultures.
Finds that the carbon benefits of mixed-species temperate forests depend partly on nitrogen availability and interactions among tree species and soils.
Finds a widespread decline in forest biomass near edges, demonstrating that fragmentation can reduce carbon stocks even where tree cover remains.
Uses GEDI lidar measurements to map vertical and horizontal forest structural complexity, an important determinant of biomass, habitat, and ecosystem functioning.
Finds that gradual warming can favor boreal tree diversity while climate extremes reverse those gains, with implications for forest resilience and carbon storage.
Shows that forest soil carbon reflects interactions among tree functional traits, standing biomass, species diversity, climate, and soil characteristics.
Identifies western U.S. forests where conserving existing high-carbon forests could simultaneously protect biodiversity and increase climate mitigation benefits.
Examines relationships between tree diversity and aboveground carbon across tropical forests and finds that biodiversity-carbon relationships depend strongly on environmental context.
Benefits of tree mixes in carbon plantings | Kathryn B. Hulvey et al. | Nature Climate Change | 2013
Argues that mixed-species plantings can improve the reliability of carbon sequestration while providing ecological benefits that monoculture carbon plantations often lack.
Forest Soils, Roots, Dead Wood, and Belowground Carbon
Finds that climatic setting can exert a stronger control on forest soil carbon fractions than experimental changes in litter inputs.
Evaluates how forestry practices and land-use transitions affect soil carbon across the highly productive Gulf Coastal Plain forest region.
Projects faster inputs to and decomposition of global deadwood carbon pools as climate change alters tree growth, mortality, and decomposition.
Synthesizes 157 studies to evaluate how afforestation alters soil carbon dioxide, methane, and nitrous-oxide fluxes under different environmental conditions.
Identifies climate, restoration age, previous land use, tree planting, and soil characteristics as major controls on soil-carbon recovery during forest restoration.
Experimental warming and drying show that climate change can increase the vulnerability of older tropical forest soil carbon to decomposition and atmospheric release.
Uses thousands of forest inventory plots to link ectomycorrhizal-tree dominance with greater tree, soil, and total forest carbon stocks.
Compares numerous forest interventions and finds distinct soil-carbon responses between natural forests and plantations.
Demonstrates that fungal community composition helps explain large-scale patterns in forest carbon storage across European forests.
Examines how forest conversion, management history, and stand conditions influence soil-carbon stocks across northeastern U.S. forests.
Finds that intensive removal of logging residues and forest-floor material poses greater risks to soil carbon and nitrogen than conventional bole-only harvesting.
Shows that the commonly assumed 50-percent carbon fraction for dead wood is systematically inaccurate and can bias global forest carbon inventories.
Synthesizes understanding of forest and rangeland soil organic carbon, including stabilization, disturbance, deep soils, measurement uncertainty, and management.
Reviews vulnerabilities of forest soil organic carbon across ecological zones and discusses management strategies for preventing losses and enhancing carbon storage.
Shows that living roots simultaneously stimulate decomposition and contribute to formation of stabilized soil organic matter in boreal forests.
Synthesizes hundreds of observations and finds that harvesting can reduce forest soil carbon, with effects varying strongly by soil depth, soil order, and management intensity.
Synthesizes evidence showing that intensive biomass harvesting can deplete forest-floor and mineral-soil carbon, particularly when residues are extensively removed.
Finds that soil carbon following afforestation varies with time, previous land use, climate, and tree type and often takes decades to show substantial gains.
Uses meta-analysis to examine how harvesting affects soil organic carbon and demonstrates especially strong sensitivity of forest-floor carbon.
Reviews harvesting, fire, fertilization, and nitrogen-fixing vegetation and shows that soil-carbon responses differ substantially among management practices.
Wildfire, Drought, Mortality, and Forest Disturbance
Shows that forest carbon-credit protocols can underestimate exposure to wildfire, drought, and other climate-driven risks that threaten long-term carbon permanence.
Documents increasing biomass losses associated with disturbance across European forests and raises concerns about the durability of the European forest carbon sink.
Shows that forest-carbon recovery following wildfire depends not only on fire severity but also on drought conditions during the recovery period.
Compares carbon consequences of prescribed fire, mechanical treatments, and other approaches intended to restore frequent-fire forests and reduce severe-fire hazards.
Demonstrates that explicitly incorporating disturbance helps reconcile conflicting estimates of carbon uptake across northern forests.
Shows that wildfire interacts with forest type, stand age, permafrost, and landscape position to determine aboveground and soil carbon stocks in boreal Alaska.
Models three decades of wildfire and ecosystem carbon dynamics and finds that combustion emissions overwhelmed net ecosystem carbon uptake across the study region.
Develops a quasi-experimental approach using forest inventory and satellite data to estimate wildfire-driven changes in aboveground forest carbon.
Examines how drought mortality, prescribed burning, and thinning influence carbon stability in forests historically adapted to frequent fire.
Shows that intensifying fires can burn deeper organic layers in boreal forests and release old soil carbon that survived previous fire cycles.
Reviews how drought and wildfire interact to affect tree mortality, productivity, combustion emissions, and long-term carbon storage across tropical forests.
Compares fire-frequency effects on aboveground carbon in harvested and unharvested forests and shows that management history changes carbon responses to repeated burning.
Compares carbon recovery after wildfire and timber harvesting and demonstrates the long-lasting influence of disturbance type on forest carbon pools.
Tests whether thinning and prescribed burning can reduce high-severity wildfire risk sufficiently to improve the long-term stability of forest carbon.
Uses paleoecological evidence and modeling to show that modern fire regimes can produce unusually large carbon losses from boreal ecosystems.
Shows how decades of fire exclusion can create forest structures vulnerable to drought and severe wildfire, increasing the risk of abrupt carbon loss.
Quantifies how different disturbance histories alter biomass accumulation and carbon stocks across eastern U.S. forests.
Projects how climate-driven increases in wildfire may affect forest carbon storage and identifies forest types most vulnerable to future carbon loss.
Evaluates whether fuel treatments can reduce carbon losses from severe wildfire enough to compensate for carbon removed or emitted during treatment.
Compares carbon stored in untreated forests with carbon consequences of thinning, prescribed fire, and subsequent wildfire.
Forest Restoration, Reforestation, Natural Regeneration, and Protection
Separates afforestation from post-disturbance reforestation and finds that regrowing previously forested land made the larger contribution to China's forest biomass carbon sink.
Finds that stronger protection and effective management are associated with greater forest carbon stocks and substantial potential future carbon benefits.
Explains why preventing the repeated clearing of young secondary forests can preserve some of the world's fastest rates of natural carbon removal.
Shows that young naturally regenerating tropical forests have exceptionally high carbon-removal rates and argues that preventing their reclearance is an important climate strategy.
Reviews ecological and social factors controlling tropical natural regeneration and its benefits for carbon, biodiversity, ecosystem services, and livelihoods.
Revisits global reforestation estimates in response to methodological critiques and refines estimates of realistic forest-based carbon mitigation potential.
Maps areas where tropical forest could plausibly regenerate naturally and quantifies substantial potential climate and biodiversity benefits.
Quantifies the contribution of China's large planted-forest expansion to biomass and ecosystem carbon storage.
Examines whether large-scale forestation can reduce warming and help reverse temperature overshoot while accounting for Earth-system feedbacks.
Evaluates assisted natural regeneration as a means of rebuilding forest structure, tree diversity, and carbon stocks in degraded dry tropical forests.
Compares natural regeneration and plantation establishment and shows that the most cost-effective restoration strategy varies geographically.
Estimates additional carbon that natural forests could store while emphasizing that conservation, restoration, biodiversity, and sustainable land use must be considered together.
Uses hundreds of millions of GEDI lidar measurements to estimate how much additional aboveground forest carbon is associated with protected-area status.
Synthesizes 24 restoration case studies and identifies conditions under which assisted natural regeneration can successfully restore forests and accumulate carbon.
Explains how removing barriers to natural forest regrowth can provide a lower-cost pathway to carbon sequestration, biodiversity restoration, and rural benefits.
Evaluates how future temperature and rainfall changes may influence the success and carbon benefits of tropical forest restoration.
Provides standardized estimates of forest ecosystem carbon that can support planning and comparison of forest restoration, reforestation, and carbon-management projects.
Maps observed carbon accumulation rates in naturally regenerating forests and demonstrates that sequestration potential varies greatly with climate and geography.
The global tree restoration potential | Jean-François Bastin et al. | Science | 2019-07-05
Estimates the potential area available for additional tree cover and stimulated extensive discussion about the scale and limitations of tree restoration as climate mitigation.
Quantifies climate-mitigation opportunities from conservation, restoration, and improved land management, with forests comprising a major share of the potential.
Forest Management, Harvesting, and Silviculture
Reviews the potential for continuous-cover forestry to combine sustained tree cover, wood production, structural complexity, and carbon sequestration.
Reviews evidence for climate-smart forestry practices intended to combine adaptation, mitigation, wood production, and long-term carbon storage.
Examines Congo Basin forests and finds that some forms of forest management can maintain high carbon density and substantial carbon sequestration.
Evaluates how thinning intensity, tree growth, soil properties, and harvest method interact to influence aboveground and soil carbon stocks.
Finds that the forest characteristics most strongly associated with carbon storage change along disturbance gradients, with large trees becoming especially important in disturbed stands.
Uses long-term empirical data to examine how partial harvesting and reduced logging intensity affect ecosystem carbon stocks, wood products, and economic outcomes.
Examines how the dominance of ectomycorrhizal and arbuscular-mycorrhizal trees relates to biomass, forest-floor, and soil carbon storage.
Investigates how species richness, tree size, niche complementarity, and dominant species influence carbon storage in contrasting forest landscapes.
Compares forest types to determine how aboveground carbon storage corresponds with tree diversity and forest structural characteristics.
Compares carbon responses to thinning in upland and drained peatland forests, showing that ecosystem context strongly controls post-harvest carbon recovery.
Measures long-term recovery of living biomass, dead wood, forest-floor, and mineral-soil carbon following different clearcut harvesting methods.
Examines limitations of treating forest carbon storage as interchangeable with fossil-fuel emissions and discusses permanence, leakage, harvest, and carbon-market incentives.
Shows how stand age, tree size, soil chemistry, forest type, and environmental conditions jointly determine carbon pools in temperate forests.
Examines how restoration thinning changes live-tree carbon in recovering redwood forests and highlights the trade-off between immediate removals and future stand development.
Synthesizes nearly 1,800 thinning comparisons and evaluates effects on tree biomass, understory vegetation, litter, roots, and soil organic carbon.
Models alternative management strategies and estimates how changes in harvest and stand management could increase carbon sequestration in Chinese forests.
Estimates the additional carbon that European forests could hold relative to current stocks and explores the mitigation value of maintaining primary forest carbon.
Finds that more intensive management can increase short-term sequestration rates while reducing standing carbon stocks and forest structural complexity.
Models forest ecosystems, harvested wood products, land-use change, and substitution effects to evaluate state-level forest-sector climate mitigation strategies.
Compares active management alternatives in mature Douglas-fir forests and quantifies consequences for standing carbon and harvested biomass.
Explains practical forest-management approaches that can maintain carbon stocks while helping forests adapt to warming, drought, disturbance, and changing growing conditions.
Synthesizes evidence on thinning, prescribed fire, harvesting, and other management treatments and their effects on forest carbon storage.
Reviews differences between managed and unmanaged forests, including stand age, carbon allocation, productivity, soil carbon, and the long-term effects of harvest.
Provides regional and individual-forest estimates of carbon retained in harvested wood products and landfills following timber harvest.
Compares forest protection and harvesting strategies and examines trade-offs among ecosystem carbon storage, harvested wood products, and ecological sustainability.
Reconstructs more than a century of carbon storage in harvested wood products and illustrates how product use and disposal affect forest-sector carbon accounting.
Draws on long-running silvicultural experiments to examine how forest-management systems can be adapted for both carbon mitigation and climate resilience.
Quantifies carbon sequestration in U.S. forests, dead wood, soils, harvested wood products, and landfills while accounting for land-use change.
Reviews studies of harvesting, forest conversion, plantations, productivity, and management effects on forest carbon storage in the northern Great Lakes.
Harvested Wood Products and the Forest Carbon Balance
Models forest carbon, harvested products, substitution effects, and climate impacts over long timescales to compare alternative forest-sector mitigation strategies.
Models cascading wood-product use followed by bioenergy with carbon capture and storage as a potential long-term forest-sector climate strategy.
Finds that satisfying future wood demand while maintaining climate benefits depends strongly on afforestation, efficient material use, recycling, and forest management.
Compares multiple forest-sector models to estimate global carbon storage in harvested wood products and expose important methodological uncertainties.
The carbon costs of global wood harvests | Liqing Peng et al. | Nature | 2023-07-05
Estimates the carbon opportunity costs associated with global timber harvesting and argues that wood demand can substantially alter land-based carbon storage.
Reviews the magnitude and longevity of carbon storage in wood products and discusses strategies for increasing their contribution to climate mitigation.
Shows that substitution benefits from wood products are not indefinitely cumulative and depend on changing energy systems, product lifetimes, and alternative materials.
Critiques simplified assumptions that replacing non-wood products with wood automatically produces large and permanent greenhouse-gas benefits.
Estimates global carbon storage in harvested wood products and evaluates how product lifetimes and future wood demand could influence mitigation potential.
Reviews carbon retained in harvested wood products and the more uncertain climate effects attributed to substituting wood for emissions-intensive materials and fuels.
Peat-Swamp Forests and Mangrove Carbon
Shows how disturbance can expose and progressively release carbon that accumulated in tropical peatlands over long periods.
Reviews carbon storage, sequestration, disturbance, restoration, and climate resilience across mangrove forests and their organic-rich soils.
Finds that conserving and restoring peat-swamp forests and mangroves could address an exceptionally large share of Southeast Asian land-use carbon emissions.
Examines where mangrove soil carbon originates and shows why distinguishing locally produced carbon from imported carbon matters for blue-carbon accounting.
Demonstrates that drainage, fire, degradation, and other disturbances produce highly variable but often substantial carbon dioxide emissions from tropical peat forests.
Evaluates the substantial carbon stocks of Amazonian mangroves and the case for including them more fully in national REDD+ strategies.
Finds that restoring historically cleared mangroves generally provides stronger carbon benefits than establishing mangroves in areas without previous mangrove cover.
Reviews how drainage, agriculture, plantations, fire, and other human activities alter tropical peat chemistry and release long-stored carbon.
Quantifies carbon lost through two decades of global mangrove land-cover change and identifies regional hotspots of carbon-stock decline.
Maps global mangrove carbon stocks and estimates potential emissions associated with mangrove deforestation during the early twenty-first century.
Forest Carbon Measurement, Inventories, Remote Sensing, and Mapping
Reconstructs global forest aboveground carbon from 1988 to 2021 and identifies major regional shifts between carbon-sink and carbon-source behavior.
Describes the national forest inventory system that supplies authoritative information on forest biomass, carbon, growth, mortality, removals, land-use change, and disturbances.
Develops statistical approaches for extracting reliable local and county-scale forest carbon trends from national forest inventory observations.
Demonstrates how updated tree-biomass equations change U.S. forest carbon estimates and create important implications for historical maps and carbon models.
Examines statistical bias and uncertainty that arise when large-scale forest-carbon estimates are applied to smaller projects, regions, and offset accounting units.
Reviews developments in forest-carbon measurement, including field inventories, remote sensing, modeling, scale problems, and improvements in estimation accuracy.
Combines remote sensing and ecosystem models to move beyond basic measurement, reporting, and verification toward identifying the causes of forest carbon changes.
Discusses satellite evidence showing strong year-to-year variation in tropical biomass carbon associated with climate anomalies and disturbance.
Uses satellite observations to investigate spatial and temporal patterns of tropical aboveground carbon gains and losses and their environmental and human drivers.
Combines GEDI lidar with other satellite datasets to improve forest aboveground biomass estimates across Indian landscapes.
Tests methods for combining simulated GEDI lidar measurements with field inventories to estimate aboveground biomass in Amazon forests.
Demonstrates how spaceborne lidar can compare forest structure and carbon stocks inside and outside protected areas.
Summarizes U.S. forest carbon stocks, sequestration, wood products, disturbances, management, and the role of national inventory data in greenhouse-gas accounting.
Explains how the Forest Inventory and Analysis program measures forest carbon stocks and fluxes using a nationwide network of permanent field plots.
Produces a globally consistent high-resolution estimate of forest aboveground biomass suitable for carbon-cycle analysis and inventory comparison.
Describes the scientific rationale and technology behind ESA's BIOMASS satellite mission for mapping forest biomass and improving global carbon estimates.
Uses satellite microwave observations to identify changes in global vegetation biomass and contrasts tropical biomass losses with gains in other regions.
Synthesizes lidar biomass studies and evaluates the accuracy and limitations of airborne and spaceborne methods for estimating aboveground carbon-related biomass.
Demonstrates that spatially explicit biomass-density maps substantially improve estimates of carbon emissions caused by tropical deforestation.
Forest Carbon Markets, REDD+, Policy, and Accounting
Re-examines criticisms of studies finding over-crediting in avoided-deforestation projects and tests whether unobserved confounding could account for the reported results.
Describes updated methods allowing local governments to incorporate forest and tree carbon removals and emissions into community greenhouse-gas inventories.
Examines causes of forest-carbon over-crediting and discusses how improved baselines, additionality tests, and project design could increase carbon-credit integrity.
Reviews REDD+ development across East and Southern Africa, including monitoring, policy integration, governance, finance, livelihoods, and forest-carbon outcomes.
Greenhouse gas accounting in the forestry sector | FAO | Food and Agriculture Organization | 2025
Provides technical guidance for estimating and reporting greenhouse-gas emissions and removals associated with forests and forestry activities.
Compares credited emissions reductions with empirical estimates across multiple carbon-credit project types, including forest-based activities.
Uses observational evidence to show how expansion and conservation of forests and other woody vegetation contributed to China's increasing biomass carbon stock.
Proposes improved methods for determining whether forest carbon projects produce climate benefits beyond what would likely have occurred without crediting.
Uses empirical evidence to test whether California forest-offset projects produced significant management changes beyond what landowners were already doing.
Uses remotely sensed forest data and comparison areas to assess whether offset projects produced carbon gains beyond plausible non-project outcomes.
Synthesizes approaches for integrating carbon conservation with timber, wildlife, water, recreation, resilience, and other forest-management objectives.
Evaluates wildfire and other reversal risks and concludes that California's shared buffer pool may be too small to guarantee credited forest carbon for the required duration.
Finds systematic problems in baseline construction that allowed some California forest-offset projects to receive more credits than estimated climate benefits justified.
REDD+: Lessons from National and Subnational Implementation | CIFOR | CIFOR-ICRAF | 2018
Reviews lessons from national, jurisdictional, and project-level REDD+ initiatives and examines the conditions affecting effectiveness, equity, governance, and climate outcomes.
Forests | Christopher W. Woodall et al. | Second State of the Carbon Cycle Report | 2018
Reviews U.S. forest carbon stocks and fluxes, disturbances, harvested wood products, land-use change, management, and future carbon-cycle vulnerabilities.
Reviews the evolution of REDD+ after the Paris Agreement and discusses tensions between carbon-centered performance metrics and broader governance, livelihood, and conservation objectives.
Examines the technical capacity required for African countries to measure forest area, carbon stocks, reference levels, emissions, and removals under REDD+.
Explores how REDD+ forest-carbon investment could interact with biodiversity, economic development, employment, landholder payments, and broader green-economy strategies.
REDD+ Subnational Initiatives | CIFOR | Center for International Forestry Research | 2013
Examines project-level REDD+ initiatives across multiple tropical countries and considers carbon effectiveness alongside livelihoods, tenure, equity, biodiversity, and local participation.
Explains the importance of credible reference levels for measuring avoided deforestation, degradation, forest conservation, sustainable management, and enhancement of carbon stocks.
