Old-Growth Forests
Old-Growth Forest Science, Ecology, and Definitions
| H.J. Andrews Experimental Forest | Oregon State University / USDA Forest Service | 2026
Provides access to decades of research from one of the world's best-studied old-growth forest ecosystems.
Uses U.S. Forest Inventory and Analysis data to project mature and old-growth forest conditions and demonstrates how the resulting information can improve wildlife-habitat studies.
| Marcin T. Mazurkiewicz et al. | Forest Ecology and Management | 2026
Old-Growth Forests
Old-growth forests are complex forest ecosystems that have developed over long periods with comparatively limited intensive human disturbance. Although age is an important characteristic, scientists generally recognize that old growth cannot be defined by tree age alone. Forest composition, disturbance history, large living trees, standing dead trees, fallen logs, canopy gaps, multiple vegetation layers, and long-term ecological processes can all contribute to old-growth conditions.
Definitions vary considerably among forest types and regions. A forest considered old growth in one ecosystem may differ substantially in age, structure, species composition, and disturbance regime from an old-growth forest elsewhere. Consequently, identifying and mapping old growth has become both a scientific and management challenge.
Old-growth forests are important not simply because they contain old trees but because they preserve ecological structures and processes that can take centuries to develop. They provide habitat for diverse organisms, store large quantities of carbon, influence water and nutrient cycles, and serve as ecological reference systems for understanding how forests function without intensive management.
Forest Structure and Ecological Development
Old-growth forests frequently contain a mixture of trees of different ages and sizes rather than a uniform stand of ancient trees. Large living trees may coexist with younger trees, standing dead trees, fallen trunks, canopy openings, and dense patches of regeneration.
Deadwood is particularly important. Standing snags and decomposing logs provide habitat for fungi, insects, birds, mammals, mosses, lichens, and other organisms. As wood decomposes, nutrients return to the soil and become available to new generations of plants.
Natural disturbances are also part of old-growth ecology. Fire, windstorms, floods, insects, disease, drought, and individual tree mortality can create openings and structural diversity without necessarily eliminating old-growth characteristics. Modern ecological research therefore increasingly views old growth as a dynamic ecosystem rather than a static final stage of forest succession.
The precise characteristics of old growth differ substantially among ecosystems. Douglas-fir forests of the Pacific Northwest, eastern hardwood forests, southern oak-pine forests, boreal forests, Australian mountain ash forests, and European forests can follow very different developmental pathways.
Biodiversity and Wildlife
Old-growth forests provide habitat for an extraordinary range of organisms. Large trees, cavities, multilayered canopies, fallen wood, moist microhabitats, and long periods of ecological continuity create niches that may be uncommon or absent in intensively managed forests.
Some species depend particularly strongly on long-term forest continuity. Research on fungi, lichens, bryophytes, insects, and other organisms demonstrates that certain species may require ecological conditions that take decades or centuries to develop.
Fungi play important roles in decomposition and nutrient cycling, while lichens and mosses can be indicators of long forest continuity. Wood-dependent insects occupy dead and decaying trees, while birds and mammals use cavities, large trees, fallen logs, and complex vegetation for nesting, feeding, shelter, and movement.
Because these ecological relationships develop over long periods, protecting existing old-growth habitat can preserve biological communities that cannot quickly be recreated after logging or other major disturbance.
Carbon Storage and Climate Change
Old-growth forests can contain enormous stores of carbon in living trees, deadwood, roots, forest soils, and other organic material. Research has challenged the earlier assumption that forests become carbon-neutral once they reach old age. Many older forests continue accumulating carbon for centuries.
Protecting existing carbon-rich forests can therefore prevent large quantities of stored carbon from being released while allowing additional carbon accumulation to continue.
Old-growth forests are themselves affected by climate change. Increasing temperatures, drought, wildfire, insects, disease, and extreme weather can increase tree mortality and alter forest structure. Long-term monitoring is increasingly important for understanding whether older forests can remain resilient under rapidly changing climatic conditions.
Old-growth forests also provide scientific baselines for comparing carbon storage, water use, productivity, and ecological resilience with younger or intensively managed forests.
Fungi, Lichens, Mosses, and Deadwood
Some of the strongest evidence for the ecological distinctiveness of old-growth forests comes from organisms associated with deadwood and long habitat continuity.
Wood-decaying fungi depend on fallen trees, standing deadwood, and other substrates that can be scarce in intensively managed forests. Research has found that rare forest fungi may depend not simply on the presence of trees but on centuries of continuous forest habitat.
Lichens can similarly respond strongly to forest age, humidity, canopy structure, and fragmentation. Certain species associated with old forests decline near forest edges or when old stands become isolated.
Mosses and liverworts also benefit from the moist and structurally diverse conditions characteristic of many older forests. Together, these organisms contribute to decomposition, nutrient cycling, moisture retention, and broader ecosystem functioning.
Old Growth as an Ecological Baseline
Because relatively undisturbed forests preserve ecological processes that have developed over long periods, old-growth forests are valuable scientific reference ecosystems.
Researchers can compare them with logged, fragmented, restored, burned, or intensively managed forests to understand how human activities and natural disturbances change ecosystems.
Long-term research sites such as the H.J. Andrews Experimental Forest have played an important role in transforming scientific understanding of forest ecology. Research in older forests helped demonstrate the importance of deadwood, canopy complexity, natural disturbance, wildlife habitat, nutrient cycling, and landscape-scale ecological processes.
These discoveries contributed to a broader transition in forestry from viewing forests primarily as collections of harvestable trees toward understanding them as complex ecological systems.
Conservation and Forest Policy
Old-growth forests have been at the center of major conservation and forest-management disputes. Debates frequently involve competing objectives including timber production, wildfire management, biodiversity conservation, carbon storage, recreation, Indigenous rights, watershed protection, and rural economies.
In the United States, federal policy debates have increasingly focused on identifying, conserving, and restoring mature and old-growth forests on public lands. Proposed management policies have generated substantial public participation and disagreement over the appropriate roles of logging, thinning, wildfire, and strict protection.
British Columbia has faced similar controversies. Provincial policies include inventories, ecosystem assessments, strategic reviews, logging deferrals, monitoring programs, and efforts to incorporate First Nations stewardship into forest planning.
European governments have also developed programs for identifying, mapping, monitoring, and protecting remaining primary and old-growth forests.
The central policy challenge is determining how existing old-growth ecosystems should be protected while also deciding how younger forests should be managed so that future old-growth conditions can develop.
Restoration and Future Old Growth
Because extensive areas of old-growth forest have been logged or altered, conservation increasingly includes attempts to restore old-growth characteristics in younger forests.
Restoration can involve allowing forests to develop naturally over long periods or actively managing them to accelerate structural complexity. Treatments may attempt to create large trees, canopy openings, standing deadwood, fallen logs, varied tree sizes, and other features associated with older forests.
Thinning is sometimes used in previously logged forests to reduce competition and encourage the development of large trees. In some ecosystems, carefully managed fire may help restore historically open forest structures.
Restoration nevertheless has limits. Structural features can sometimes be encouraged, but centuries of ecological continuity cannot simply be manufactured. Some organisms disperse slowly or depend on habitat conditions created only through very long periods of uninterrupted forest development.
For this reason, protecting surviving old growth and developing future old growth are complementary rather than interchangeable conservation strategies.
Pacific Northwest and Tongass Old Growth
The Pacific Northwest played a major role in the development of modern old-growth forest science. Research in Douglas-fir forests demonstrated that ancient forests are structurally complex ecosystems containing large living trees, standing dead trees, massive fallen logs, canopy gaps, and large woody material in streams.
These discoveries helped overturn earlier ideas that old forests were biologically stagnant or economically obsolete.
The Tongass National Forest in Southeast Alaska contains extensive temperate rainforest and some of North America's most significant remaining old-growth landscapes. Its forests provide wildlife habitat, store carbon, support fisheries and watersheds, and have long-standing cultural importance for Indigenous communities.
Logging and road construction in the Tongass have consequently produced decades of political, ecological, and legal controversy.
Eastern and Southern Old-Growth Forests
Although much public attention has focused on western forests, remnants of old growth survive throughout the eastern and southern United States.
These include hardwood forests, oak-pine ecosystems, hemlock-white pine forests, Cross Timbers woodlands, and other forest communities. Their structures reflect regional differences in climate, soils, fire, flooding, storms, and land-use history.
Many eastern old-growth remnants are comparatively small because extensive logging and agricultural clearing transformed much of the landscape during earlier centuries.
These surviving forests nevertheless provide valuable ecological benchmarks for understanding pre-industrial forest conditions and guiding restoration of younger forests.
Old-Growth Forests Around the World
Old-growth forests occur in many ecological regions, and there is no single global definition that applies equally well everywhere.
European researchers and policymakers distinguish among primary, ancient, natural, secondary, and old-growth forests. Remaining forests with long ecological continuity are particularly important for species that have difficulty surviving intensive forestry and fragmented landscapes.
Canada contains extensive old-growth ecosystems, especially in British Columbia, where coastal temperate rainforests support large trees, diverse wildlife, substantial carbon stores, and important Indigenous cultural values.
Australian research emphasizes the importance of large old trees and complex forest structure, particularly in mountain ash ecosystems.
Research from boreal, temperate, tropical, and Afrotropical forests further demonstrates that older forests can make important contributions to biodiversity conservation and long-term carbon storage.
Indigenous Stewardship and Cultural Values
Old-growth forests have cultural, spiritual, historical, recreational, and aesthetic significance in addition to their ecological importance.
Indigenous peoples have maintained relationships with many ancient forest landscapes for generations. Indigenous ecological knowledge can contribute important understanding of fire, wildlife, plants, forest succession, and long-term landscape stewardship.
In regions such as British Columbia and Southeast Alaska, debates over old-growth conservation increasingly involve Indigenous governments and communities whose territories include ancient forests.
Old forests have also influenced literature, philosophy, environmental ethics, recreation, scientific education, and public understanding of nature. Their value therefore cannot be measured solely through timber production or carbon accounting.
Threats to Old-Growth Forests
Logging remains one of the most direct threats to old-growth ecosystems because removing ancient trees can eliminate structures that require centuries to redevelop.
Fragmentation can also change conditions within forests that remain standing. New edges alter temperature, humidity, wind exposure, and other microclimatic conditions, potentially affecting organisms adapted to stable interior forest environments.
Climate change creates additional pressures through drought, heat, wildfire, insects, disease, and changing disturbance regimes. Development, roads, invasive species, and altered hydrology can further affect old forests.
These interacting pressures mean that preserving individual old trees alone may not be sufficient. Maintaining landscape connectivity, ecological processes, deadwood, watersheds, and surrounding habitat can also be important for preserving functioning old-growth ecosystems.
Conclusion
Old-growth forests are not simply collections of exceptionally old trees. They are complex ecosystems produced through long periods of growth, mortality, decomposition, disturbance, and regeneration.
Their ecological importance comes from this accumulated complexity. Large trees, deadwood, canopy layers, long habitat continuity, diverse organisms, soils, waterways, and natural disturbances interact to create ecosystems that can be difficult or impossible to reproduce quickly once lost.
Scientific research has demonstrated that old-growth forests can support distinctive biodiversity, provide important wildlife habitat, store substantial quantities of carbon, regulate water and nutrients, and serve as reference ecosystems for understanding forest change.
At the same time, old-growth conservation remains a major policy challenge. Governments, Indigenous communities, scientists, conservation organizations, forest managers, and local communities continue to debate how remaining ancient forests should be protected and how younger forests should be managed.
The research ultimately emphasizes an important distinction between preserving existing old growth and creating future old growth. Restoration can help younger forests regain structural complexity, but ecological continuity takes time. Protecting surviving old-growth ecosystems therefore preserves biological and ecological legacies that may have taken centuries to develop and could require centuries to replace.
Finds that old-growth temperate forests support distinctive taxonomic and functional diversity among bryophytes compared with managed forests.
| USDA Forest Service Southern Region | USDA Forest Service | 2026
Provides updated guidance for identifying, evaluating, monitoring, restoring, and managing old-growth forest communities across the southern United States.
| Researchers in Finland | Biodiversity and Conservation | March 10, 2026
Compares lichen communities on understory rowan trees in managed, urban, and old-growth forests of southern Finland.
| Margaret Woodbridge, J. Davis Goode and Don C. Bragg | USDA Forest Service | 2025
Provides an extensive annotated bibliography covering the scientific and historical literature on old-growth forests of the southeastern United States.
| Stephen Fitzgerald and Gretchen Bracher | Oregon State University Extension | 2025
Places old-growth forests within the larger process of forest succession and explains how structural complexity develops through time.
| Various researchers | Biological Conservation | 2025
Systematically compares biodiversity in European boreal old-growth forests, managed forests, and recent clearcuts across numerous taxonomic groups.
| Mattia Letizia Marino, Patrizia Campisi and Fortunato Cirlincione | Plants | September 10, 2025
Reviews relationships between old-growth forest characteristics and bryophyte diversity in Italy and the wider Mediterranean region.
Reviews mosses, liverworts, ecological continuity, deadwood, forest naturalness, and indicator species associated with Mediterranean old-growth forests.
| Dominick A. DellaSala et al. | Biological Conservation | June 2025
Estimates how much additional carbon could remain stored if mature and old-growth forests across the United States received stronger protection.
| Ethan A. Frye et al. | Journal of Forestry | January 29, 2025
Examines how scientists define and measure second-growth, mature, and old-growth forests and documents substantial differences among scientific definitions.
| USDA Forest Service | USDA Forest Service Research and Development | 2024
Reviews federal research used to identify, classify, inventory, and understand mature and old-growth forests across the United States.
| Yale Forest Forum | Yale University | 2024
Brings together scientists, forest managers, conservationists, industry representatives, and Indigenous knowledge experts to examine old-growth conservation under climate change.
| Piotr Osyczka, Robert Kościelniak and Małgorzata Stanek | Mycologia | 2024
Studies whether physiological sensitivity helps explain why some lichens are restricted to old and ecologically continuous forests.
| Marta Pardos et al. | European Journal of Forest Research | December 11, 2024
Investigates carbon-storage potential in successional and secondary old-growth pine forests in Spain.
| Government of British Columbia | Province of British Columbia | December 4, 2024
Provides an overview of British Columbia's old-growth forests, management policies, strategic review, conservation efforts, and forest stewardship reforms.
| Anthony D'Amato | Yale Forest Forum | November 14, 2024
Examines silvicultural strategies for developing and maintaining mature and old-growth forest characteristics across multiple ownership types.
| Michael Farinacci et al. | AGU Advances | July 18, 2024
Compares carbon production, water use, and water-use efficiency in young and mature/old-growth watersheds in Oregon's H.J. Andrews Experimental Forest.
| Government of British Columbia | Province of British Columbia | May 21, 2024
Explains British Columbia's age-based definitions of old growth and describes ecological, cultural, recreational, social, and economic values.
| Sue Miller, Kristen A. Pelz and Andy Gray | USDA Forest Service | March 2024
Explains development of the first nationally consistent Forest Inventory and Analysis method for estimating old-growth forest extent.
| Piotr Osyczka, Robert Kościelniak and Małgorzata Stanek | Mycologia | January 2024
Compares physiological responses to drying and rehydration between lichens associated with old-growth forests and widespread generalist species.
Explains why defining old-growth forests is scientifically difficult and examines tree age, forest structure, ecological processes, cultural values, and changing scientific terminology.
| Kristen A. Pelz et al. | Forest Ecology and Management | December 1, 2023
Uses Forest Inventory and Analysis data to estimate the amount and distribution of old-growth forest on U.S. National Forest System lands.
| Andrew N. Gray et al. | Forest Ecology and Management | October 15, 2023
Describes defining old growth as a "wicked problem" involving ecology, forest structure, human values, Indigenous history, policy, and management.
| Mason Cummings | The Wilderness Society | February 23, 2023
Explains why forest age alone cannot adequately define old growth and discusses biomass, forest development, regional variation, and national inventories.
| Sara Khatib | University of Oregon / H.J. Andrews Experimental Forest | 2021
Investigates how scientific understanding and definitions of old-growth forest developed through research at the H.J. Andrews Experimental Forest.
| Diane E. Yorke | University of New Hampshire Cooperative Extension | 2016
Describes the ecological features of old-growth forests and explains how some of those habitat structures can be incorporated into managed forests.
| University of New Hampshire Cooperative Extension | UNH Extension | 2007
Explains old-growth forest structure and how features such as large trees, snags, canopy gaps, and fallen logs can be restored in younger forests.
| Posy Elizabeth Busby | Harvard University / H.J. Andrews Experimental Forest | 2002
Examines the history of old-growth terminology and the interaction between ecological science, forest management, industry, and conservation.
| David L. White and F. Thomas Lloyd | USDA Forest Service | 1998
Describes structural characteristics, tree ages, historical conditions, and fire regimes of old-growth oak-pine forests.
| Kelly Kindscher and Jenny Holah | USDA Forest Service | 1998
Defines old-growth western hardwood gallery forests and discusses the role of river hydrology, flooding, succession, and human alteration.
| Cathryn H. Greenberg, Donald E. McLeod and David Loftis | USDA Forest Service | 1997
Develops an ecological definition of old growth for western and mixed mesophytic forests and reviews the history of Forest Service old-growth definitions.
| William B. Batista and William J. Platt | USDA Forest Service | 1997
Defines old-growth southern mixed hardwood forests using surviving exemplary stands, tree composition, disturbance history, and forest dynamics.
| D. M. Graber | Tropics / U.S. Geological Survey | 1997
Examines management of giant sequoia and coast redwood reserves and the transition from protecting individual old stands toward ecosystem management.
| D. M. Graber | U.S. Geological Survey | 1997
Provides the USGS publication record for research on conserving biodiversity and ecosystem processes in old-growth sequoia and redwood forests.
| Joel Schwarz | University of Washington | April 8, 1997
Examines disagreements over mapping and estimating remaining old-growth forest in the Pacific Northwest.
| Merrill R. Kaufmann, W. H. Moir and Richard L. Bassett | USDA Forest Service | 1992
Collects scientific perspectives on old-growth forests in the Southwest and Rocky Mountains, including definitions, ecology, wildlife, and management.
| Various authors | ScienceDirect Topics | n.d.
Provides an overview of scientific literature concerning old-growth forest ecology, classification, structure, biodiversity, carbon, and conservation.
Forest Structure, Development, and Ecological Processes
| Jesse D. Young and Alan Ager | USDA Forest Service Rocky Mountain Research Station | 2024
Explains research into using lower-severity wildfire to restore historically open old-growth forests in the southwestern United States.
| Kristen A. Pelz et al. | Forest Ecology and Management | 2023
Develops a standardized method for estimating the extent of old-growth forest on U.S. National Forest System lands.
| Andrew N. Gray et al. | Forest Ecology and Management | 2023
Describes defining and inventorying old growth as a complex problem involving ecology, policy, history, cultural values, forest structure, and management.
| Jesse D. Young and Alan Ager | Ecological Modelling | 2023
Models whether managed wildfire can help restore old-growth forest structure while maintaining landscape carbon storage.
| David Lindenmayer and Elle Bowd | Frontiers in Forests and Global Change | 2022
Uses Australia's mountain ash forests to examine the ecological roles, structural attributes, decline, and conservation of old-growth forest.
| Kerry D. Woods and Christel C. Kern | Ecosphere | 2022
Uses an 84-year record to show how intermediate disturbances drive long-term changes in biomass within an old-growth temperate forest.
| Michael L. Ferro and Joseph V. McHugh | Insect Systematics and Diversity | June 30, 2022
Tests whether two saproxylic beetles are truly dependent on old-growth conditions in the southern Appalachian Mountains.
| Gianluca Piovesan et al. | Environmental Chemistry Letters | January 5, 2022
Reviews ecological and human-health benefits associated with old forests and exceptionally large, ancient trees.
Carbon Storage and Climate Change
| Stanford University | Stanford Report | March 19, 2026
Reports research finding that Swedish primary forests hold substantially more carbon than intensively managed forests, with especially large differences in soil carbon.
| USDA Forest Service | Southern Research Station | May 2, 2025
Models future mature and old-growth forest extent through 2070 under different climate, wildfire, and tree-removal scenarios.
| Alvin Powell | Harvard Gazette | March 2025
Explores long-term forest research, shifting ecological baselines, climate change, and the importance of experiencing intact older forests.
| USDA Forest Service Northern Research Station | USDA Forest Service | June 2024
Reviews carbon storage potential in old-growth forests of the Central Hardwoods region and discusses climate-adaptive forest management.
| Sarah Hertel | One Earth | June 23, 2024
Describes a coast-to-coast assessment of mature and old-growth forests and their importance for both carbon storage and biodiversity.
| Cara Cannon Byington | Cool Green Science / The Nature Conservancy | February 4, 2024
Reviews research into whether management treatments can accelerate development of old-growth characteristics in previously logged coastal forests.
| N. V. Lukina et al. | Bulletin of the Russian Academy of Sciences: Geography | 2023
Reviews the role of old-growth forests in carbon accumulation and long-term carbon storage.
| Āris Jansons et al. | Forest Science | 2023
Examines carbon storage in hemiboreal old-growth coniferous and deciduous forests and implications for forest and climate policy.
Examines rising tree mortality in old-growth forests and the need for improved monitoring as forests face warming, drought, and other climate stresses.
| The Nature Conservancy | The Nature Conservancy | 2022
Discusses forest carbon durability and why protecting existing carbon-rich forests is important in nature-based climate strategies.
| The Wilderness Society | The Wilderness Society | May 12, 2022
Reviews climate regulation, carbon storage, drinking water protection, wildlife habitat, biodiversity, and other benefits provided by older forests.
| John R. Poulsen et al. | Global Ecology and Biogeography | 2020
Examines the importance of intact old-growth Afrotropical forests for maintaining large aboveground carbon stocks.
| Altamash Bashir, David A. MacLean and Chris R. Hennigar | Annals of Forest Science | April 3, 2019
Investigates carbon sequestration and carbon dynamics in older hardwood- and softwood-dominated stands of Canada's Acadian Forest.
| Clara Chaisson | Natural Resources Defense Council | June 12, 2017
Describes research aimed at recreating old-growth structural complexity in northeastern forests to improve biodiversity and carbon storage.
| Jennifer C. McGarvey et al. | Ecology | 2015
Measures carbon stocks in Mid-Atlantic old-growth forests and compares them with surrounding younger secondary forests.
| Harvard Gazette | Harvard University | April 2014
Shows how droughts, severe frost, and other climatic events have shaped the age structure of surviving eastern old-growth forests.
| Various researchers | Forest Ecology and Management | February 15, 2012
Establishes benchmark carbon-stock estimates from remnant old-growth forests in Maine, Vermont, and New Hampshire.
| Oregon State University | OSU News | January 27, 2009
Summarizes influential research demonstrating that old-growth forests can continue accumulating carbon for centuries rather than becoming carbon-neutral.
| Sebastiaan Luyssaert et al. | Nature | September 11, 2008
Challenges the assumption that old forests become carbon-neutral and presents evidence that many continue accumulating atmospheric carbon for centuries.
| Sebastiaan Luyssaert et al. | Nature / PubMed | September 11, 2008
Summarizes global evidence showing positive net ecosystem productivity in many forests ranging from young stands to forests hundreds of years old.
| The Nature Conservancy | The Nature Conservancy | n.d.
Discusses carbon storage and climate resilience in Pacific Northwest coastal forests and experiments designed to restore old-growth conditions.
Biodiversity, Wildlife, Fungi, and Other Organisms
| National Park Service | New River Gorge National Park and Preserve | 2025
Describes remnant old-growth forests in West Virginia and explains how large trees, woody debris, and layered canopies create complex wildlife habitat.
| Parks Canada | Government of Canada | 2025
Examines old-growth forest as a protected habitat within Kejimkujik National Park and National Historic Site.
| Government of British Columbia | Province of British Columbia | 2024
Reviews the ecological importance of old-growth forests and the hundreds of plant and animal species that depend on older forest habitat.
| Government of British Columbia | Province of British Columbia | July 5, 2024
Describes a permanent-plot research network studying the structure, composition, function, and long-term dynamics of coastal old-growth forests.
| Parks Canada | Government of Canada | May 3, 2024
Describes old-growth hemlock and hardwood forests at Kejimkujik and their importance to lichens, orchids, birds, mammals, and other organisms.
| Various researchers | Forest Ecology and Management | August 1, 2023
Finds that long forest continuity is particularly important for conserving rare wood-inhabiting fungi associated with old-growth ecosystems.
| Timothy Schowalter | Forests / H.J. Andrews Experimental Forest | 2017
Reviews arthropod biodiversity in North American old-growth forests and the importance of insects in nutrient cycling, decomposition, and ecosystem resilience.
| Audubon Alaska | Audubon Alaska | 2016
Maps productive old-growth forests in Southeast Alaska and describes their uneven-aged structure, wildlife habitat, and ecological importance.
| Alejandro Ruete, Tord Snäll and Mari Jönsson | Ecological Applications | February 25, 2016
Examines how anthropogenic forest edges influence the distribution and diversity of fungi in fragmented Swedish old-growth forests.
| Swantje Löbel, Tord Snäll and Håkan Rydin | Journal of Applied Ecology | 2012
Finds that forest edges and isolated retention trees can reduce growth and reproduction of bryophytes associated with old forests.
| Various researchers | Biological Conservation | December 2011
Compares bryophyte communities among young, mature, and old-growth wet eucalypt forests in Tasmania.
| Audubon South Carolina | National Audubon Society | 2009
Explains the characteristics and ecological benefits of old-growth swamp forest, including wildlife cavities, fallen logs, watershed protection, and biodiversity.
| Mari Jönsson et al. | Journal of Ecology | August 12, 2008
Follows colonization and extinction of wood-decaying fungi in boreal old-growth Norway spruce forest.
| Per-Anders Esseen | Journal of Vegetation Science | February 24, 2006
Measures how natural forest edges influence the old-growth indicator lichen Alectoria sarmentosa in northern Sweden.
| Håkan Berglund | Ecological Applications | June 1, 2005
Examines temporal variation in wood-fungus diversity and the implications for biodiversity monitoring in boreal old-growth forests.
| A. L. Rosso, B. McCune, T. Tønsberg and C. Printzen | Evansia / U.S. Geological Survey | 1999
Documents lichen diversity within a relatively unexplored old-growth forest in western Oregon.
Finds substantially greater epiphytic lichen biomass on spruce branches in old-growth boreal forests than in managed stands.
| Donald S. Chandler and Stewart B. Peck | Environmental Entomology | December 1, 1992
Compares beetle diversity and seasonality in an old-growth New Hampshire forest and a nearby 40-year-old forest.
| Leonard F. Ruggiero and Andrew B. Carey | Society of American Foresters | 1984
Describes a major research program investigating relationships between old-growth Douglas-fir forests and wildlife in the Pacific Northwest.
| The Nature Conservancy | The Nature Conservancy | n.d.
Describes an ancient Cross Timbers forest in Oklahoma containing post oak and redcedar trees hundreds of years old.
| The Nature Conservancy | The Nature Conservancy | n.d.
Profiles one of northeastern Pennsylvania's largest surviving old-growth forests and its mixture of white pine, hemlock, maple, oak, and other species.
| The Nature Conservancy | The Nature Conservancy | n.d.
Describes an old-growth Texas woodland containing mature post oak, pine, hardwood, upland, and bottomland forest communities.
| The Nature Conservancy | The Nature Conservancy | n.d.
Profiles a rare old-growth eastern hemlock and white pine forest surviving within a developed landscape in New York.
| The Nature Conservancy | The Nature Conservancy | n.d.
Describes California's Angelo Coast Range Reserve and its extensive old-growth Douglas-fir forest, wildlife, streams, salmon, and conservation history.
Restoration and Forest Management
| American Forests | American Forests | 2025
Evaluates forest-management scenarios involving mature and old-growth forest resilience, fire treatments, conservation, and harvest rotations.
| Government of British Columbia | Province of British Columbia | 2025
Assesses current old-growth forest conditions, cumulative impacts, wildlife habitat, Indigenous values, logging, development, and conservation.
| Daniel J. Herrera et al. | Forest Ecology and Management | November 15, 2025
Uses national forest inventory data to model mature and old-growth conditions and tests their relevance for wildlife habitat.
| Julee Boan and Rachel Plotkin | Natural Resources Defense Council | November 13, 2024
Examines how industrial forestry alters natural forest age and species composition and contrasts managed forests with older ecosystems.
| Government of British Columbia | Province of British Columbia | February 13, 2023
Outlines a provincial vision emphasizing conservation of ancient forests, Indigenous partnerships, resilience, and sustainable forestry.
| National Park Service | Redwood National and State Parks | April 18, 2022
Explains how restoration thinning is being used to accelerate development of old-growth-like conditions in previously logged redwood forests.
| Vincent Miller | Commonweal / H.J. Andrews Experimental Forest | 2020
Explores ecological relationships, decay, regeneration, human values, and spirituality within an old-growth forest landscape.
| Oregon State University | Oregon State University | June 16, 2020
Explores ecological discoveries from long-term old-growth forest research and their implications for environmental ethics.
| Virginia Tech | Virginia Tech | July 5, 2016
Presents a stewardship plan for Virginia Tech's old-growth forest, including ecological characteristics, regeneration, threats, and management.
| Christophe Bouget et al. | Animal Conservation | 2014
Tests whether setting forests aside from harvesting restores old-growth structural characteristics and saproxylic beetle communities.
| USDA Forest Service | USDA Forest Service | 2014
Examines techniques for accelerating development of large trees, deadwood, canopy gaps, and other characteristics associated with old forests.
| James T. Tanner and Paul Hamel | USDA Forest Service | 2001
Takes a long-term view of old-growth deciduous forests and discusses their survival, ecological structure, wildlife, research, recreation, and management.
| Lucy E. Tyrrell et al. | USDA Forest Service | 1998
Compiles structural characteristics and quantitative benchmarks for nine old-growth forest groups across the eastern United States.
| David L. White and F. Thomas Lloyd | USDA Forest Service | 1994
Discusses how definitions of old growth influence conservation objectives and forest-management decisions.
| The Nature Conservancy | The Nature Conservancy | n.d.
Describes efforts in Maryland to restore structural characteristics associated with old-growth Appalachian forests.
Conservation, Forest Policy, and Protection
| Old-Growth Forest Network | Old-Growth Forest Network | December 23, 2025
Reviews dozens of forests added to the Old-Growth Forest Network during 2025.
| Old-Growth Forest Network | Old-Growth Forest Network | July 23, 2025
Reports a resolution adopted at the American Forest Congress supporting stronger protection and expansion of old-growth forests.
| Government of British Columbia | Province of British Columbia | May 29, 2025
Describes temporary logging deferrals intended to conserve vulnerable old-growth forests while longer-term stewardship plans are developed.
| Government of British Columbia | Province of British Columbia | May 29, 2025
Details legally enforceable old-growth logging deferrals in areas including the Central Walbran and Incomappleux Valley.
| Government of British Columbia | Province of British Columbia | March 20, 2025
Describes provincial monitoring and public reporting on the condition and distribution of old-growth forests.
| Government of British Columbia | Province of British Columbia | 2024
Documents British Columbia's strategic review of old-growth management and its recommendations for changing provincial forest policy.
| Gabrielle Berthel | Natural Resources Defense Council | September 24, 2024
Reviews the public debate surrounding the National Old Growth Amendment and proposed protections for federal forests.
| Blake Busse | The Pew Charitable Trusts | September 16, 2024
Examines U.S. Forest Service plans for conservation and restoration of old growth amid increasing threats from wildfire, drought, insects, disease, and climate change.
| Earthjustice | Earthjustice | June 20, 2024
Discusses the draft environmental review for the proposed nationwide U.S. old-growth forest plan amendment.
| Government of British Columbia | Province of British Columbia | May 21, 2024
Provides scientific analysis, maps, technical reports, and information used to identify old-growth ecosystems considered at risk.
| Earthjustice | Earthjustice | March 14, 2024
Describes political disagreement over proposed federal protections for old-growth forests and trees.
| The Pew Charitable Trusts | Pew | February 2, 2024
Evaluates proposed nationwide changes to U.S. Forest Service management plans intended to conserve and restore old-growth forest conditions.
| Earthjustice | Earthjustice | December 19, 2023
Reports the federal proposal to establish nationwide management direction for old-growth forests on National Forest System lands.
| Earthjustice | Earthjustice | July 20, 2023
Covers public advocacy for stronger federal protection of mature and old-growth forests from logging.
| Old-Growth Forest Network | Old-Growth Forest Network | 2019
Explains efforts to establish a national network of permanently protected native old-growth forests accessible for education, recreation, research, and conservation.
| Alix Murdoch | The Nature Conservancy | n.d.
Discusses public attitudes toward conserving old-growth forests while continuing selected forest-management practices.
| Yale Forest Forum | Yale University | n.d.
Explains how ecological thinking moved beyond the traditional concept of old-growth forest as a static climax state toward a dynamic ecosystem model.
Pacific Northwest, Alaska, and the Tongass
| National Park Service | New River Gorge National Park and Preserve | 2025
Provides an educational old-growth forest trail highlighting tree age, forest structure, decomposition, and dendrochronology.
| National Park Service | New River Gorge National Park and Preserve | July 16, 2025
Explains how definitions of old growth depend on forest type, disturbance history, tree longevity, and regional ecological conditions.
| Earthjustice | Earthjustice | March 19, 2024
Explains the ecological and climatic importance of Alaska's Tongass National Forest and ongoing disputes over logging and road construction.
| National Park Service | New River Gorge National Park and Preserve | September 20, 2023
Describes tree-ring research confirming that some trees in West Virginia's Burnwood forest date to the seventeenth century.
| The Wilderness Society | The Wilderness Society | January 3, 2022
Examines logging, climate, wildlife, Indigenous communities, and conservation issues within the Tongass National Forest.
| Earthjustice | Earthjustice | March 11, 2020
Reports a federal court decision involving a major old-growth timber and road-building project on Prince of Wales Island in Alaska.
| National Park Service | Mount Rainier National Park | 2018
Introduces the ecology, age, structure, wildlife habitat, and history of Mount Rainier's extensive old-growth forests.
| Oregon State University | Spring Creek Project | 2016
Describes a collection bringing scientists, poets, writers, and philosophers together to examine the ecological and human meaning of old-growth forest.
| Earthjustice | Earthjustice | March 24, 2015
Covers litigation concerning the Big Thorne timber sale and proposed logging of thousands of acres of Tongass old-growth forest.
| Matt Miller | Cool Green Science / The Nature Conservancy | July 29, 2013
Compares Southeast Alaska old-growth forest with young forests created after clear-cut logging and examines ecological restoration.
| M. L. Herring | H.J. Andrews Experimental Forest | 2011
Provides an accessible exploration of the ecological complexity and scientific significance of Pacific Northwest old-growth forest.
Explains how old-growth forests vary across disturbance regimes and discusses their ecological diversity, carbon, wildlife, and management.
| Oregon State University | OSU News | May 12, 2009
Discusses differing scientific, economic, philosophical, cultural, and industry perspectives on Pacific Northwest old-growth forests.
| Valerie Rapp | USDA Forest Service Pacific Northwest Research Station | 2003
Summarizes discoveries showing that old-growth forests develop through multiple pathways involving natural disturbance and structural complexity.
| Lance Robertson | The Register-Guard / H.J. Andrews Experimental Forest | August 23, 1998
Profiles the H.J. Andrews Experimental Forest and its importance in the scientific study of old-growth ecosystems.
| Jerry F. Franklin et al. | USDA Forest Service Pacific Northwest Research Station | 1981
Identifies large live trees, snags, fallen logs, and large wood in streams as fundamental structural characteristics of old-growth Douglas-fir ecosystems.
| Jerry F. Franklin et al. | H.J. Andrews Experimental Forest | 1980s
Provides a foundational scientific synthesis of old-growth Douglas-fir forest structure, ecosystem functions, biodiversity, and deadwood.
| U.S. Geological Survey | USGS | n.d.
Describes the exceptionally productive old-growth lowland and temperate rainforest ecosystems of Olympic National Park.
Eastern and Southern U.S. Old-Growth Forests
| S. L. Clark and S. W. Hallgren | USDA Forest Service | 2004
Characterizes an old-growth Cross Timbers oak forest in Oklahoma and tests whether its structure matches traditional old-growth models.
Uses more than six decades of measurements to examine stand dynamics in an old-growth hardwood forest in southern Illinois.
| David Orwig, Charles Cogbill, David Foster and John O'Keefe | Harvard Forest | 1996–1997
Provides tree, sapling, understory, and coarse-woody-debris data from old-growth forest research on Wachusett Mountain, Massachusetts.
| Harvard Forest | Harvard University | n.d.
Describes a remnant Massachusetts old-growth forest that survived centuries of regional farming, logging, and land-use change.
Canada and British Columbia
| Government of British Columbia | Province of British Columbia | 2025
Assesses old-growth forest condition, ecological structure, management areas, biodiversity, and cumulative effects in British Columbia's Cariboo-Chilcotin region.
| Government of British Columbia | Province of British Columbia | 2024
Summarizes ecological, cultural, spiritual, climate, watershed, biodiversity, and economic values associated with British Columbia's old-growth forests.
European Old-Growth Forests
| European Commission Directorate-General for Environment | European Commission | March 21, 2023
Provides official European Union guidance for defining, mapping, monitoring, and strictly protecting remaining primary and old-growth forests.
| International Union of Forest Research Organizations | IUFRO | n.d.
Coordinates international research on old-growth ecology, forest reserves, biodiversity conservation, harvesting impacts, and restoration.
Australian Old-Growth Forests
| Australian Government | Department of Agriculture, Fisheries and Forestry | n.d.
Summarizes the extent, assessment, conservation status, and reservation of identified old-growth forests across Australian Regional Forest Agreement areas.
| Parliament of Australia | Australian Parliament | n.d.
Discusses definitions, conservation values, logging impacts, and policy options for protecting old-growth forests.
Global Old-Growth Forests
| European Commission Joint Research Centre | European Commission | 2021
Reviews terminology and definitions used to distinguish primary, ancient, natural, secondary, and old-growth forests in Europe.
| United Nations Environment Programme | UNEP | 2002
Discusses global environmental trends including the decline, ecological importance, carbon storage, biodiversity, hydrology, and cultural value of old-growth forests.
Indigenous Stewardship and Cultural Values
| Conservation International | Conservation International | 2026
Uses photography and conservation science to document globally important carbon-rich ecosystems, including old-growth temperate rainforests.
| Will McCarry | Conservation International | June 16, 2026
Examines Indigenous ecological knowledge and the role Indigenous communities play in protecting carbon-rich ancient and old-growth forests.
| Harvard University | Harvard Gazette | April 17, 2025
Describes learning from First Nations knowledge holders while exploring ancient forests and culturally important old-growth trees on Vancouver Island.
| Parks Canada | Government of Canada | April 13, 2022
Describes the cultural and historical significance of Gillies Grove, a surviving Canadian old-growth white pine forest.
| Colleen Walsh | Harvard Gazette | March 2019
Discusses Richard Powers' encounters with remnant old-growth forests and how ancient forests influenced his understanding of ecological complexity.
| The Nature Conservancy | The Nature Conservancy | n.d.
Describes efforts with First Nations to protect the old-growth temperate rainforest of Clayoquot Sound while supporting sustainable local economies.
Public Debate and Forest-Management History
| Stanford University | Stanford Report | July 2026
Discusses habitat protection under the Endangered Species Act, including implications for species dependent on old-growth forests such as the northern spotted owl.
| Stanford University | Stanford Report | March 2025
Places old-growth forest protection within the history and changing strategy of the American environmental movement.
| Stanford University | Stanford Report | February 15, 2024
Reports research showing declines in long-lived, shade-tolerant species associated with old-growth conditions in protected Mesoamerican forests.
| Stanford University | Stanford Report | October 2015
Describes field-based study of Southeast Alaska communities, climate change, logging, fisheries, and old-growth forest landscapes.
| Tim Stephens | UC Santa Cruz | September 13, 2004
Discusses former Interior Secretary Bruce Babbitt's role in environmental policy, including the Pacific Northwest old-growth forest debate.
| University of California, Berkeley | Rausser College of Natural Resources | 2001
Reviews old-growth forests as one of the central public-land conservation conflicts in modern U.S. forest-management history.
| UC Santa Cruz | University of California, Santa Cruz | January 1995
Provides historical context for academic research into political conflict surrounding ancient forests and old-growth forest management.
