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Mature and Old Growth Forests

A patch of large old growth ponerosa pine trees.
Old-growth ponderosa pine forests in Long Valley and Fort Valley Experimental Forests provide a window into historical spatial patterns of trees and non-forested openings. Some of the last remaining old-growth ponderosa pine occurs in Long Valley and Fort Valley Experimental Forests in& Arizona. Research quantifying the spatial patterns of both trees and openings provides valuable insights for managers designing restoration. (USDA Forest Service photo)

What's New

The Forest Service and Bureau of Land Management conducted a series of webinar engagement sessions, throughout the month of July 2023, to share information about the mature and old-growth forest initiative progress. The robust engagements provided an opportunity for participants ask questions and share thoughts about what should considered during the upcoming threat analysis process. There was an overall recognition that mature and old-growth forests contribute to carbon uptake and storage and great dialogue on other topics such as active management, timber harvest and climate impacts.


The Forest Service and Bureau of Land Management are conducting a mature and old-growth forests threat analysis, as required by Executive Order 14072. The analysis will address concerns about the durability, distribution and redundancy of mature and old-growth forests in light of potential threats like wildfire, insects, disease and changing climate. Recognizing the value of Indigenous Knowledge, other perspectives, and local knowledge, the agencies will continue to engage Tribes, Alaska Native Corporations, agency staff, stakeholders and the public throughout this process.

The threat analysis and resulting report will identify and examine threats to mature and old-growth forests, compile geospatial layers that represent these threats, and conduct a geospatial threat analysis of the mature and old-growth forests that were identified in the inventory. A final report is expected to be available in the winter.


On April 22, 2022, the Biden Administration released Executive Order 14072: “Strengthening the Nation’s Forests, Communities and Local Economies.” The Executive Order requires that the U.S. Departments of Agriculture and the Interior to:

  • coordinate conservation and wildfire risk reduction activities,
  • define mature and old-growth forests on federal lands,
  • complete an inventory and make it publicly available,
  • identify threats to mature and old-growth forests,
  • develop policies to address threats,
  • develop Agency-specific reforestation goals by 2030,
  • develop climate-informed reforestation plan,
  • develop recommendations for community-led local and regional economic development opportunities.

The definitions and an initial inventory of mature and old-growth forests on Forest Service lands were released April 20, 2023, and will help guide local land management efforts to steward these forests for generations to come. Details are available in a technical report. A national map of mature and old growth forests on federal is available in the Climate Risk Viewer. The inventory is expected to be periodically updated, which will allow monitoring of the status of mature and old-growth forests.

Early attempts at defining old-growth forest date back to the 1940s, when the term old growth was used to differentiate slower-growing, older forests from faster-growing younger forests. The idea was largely based on the diameter at breast height of the largest live trees. Discussions around what constitutes old growth expanded in the 1970s with a burgeoning environmental movement.

By the late 1980s, a generic definition adopted to guide the Forest Service. Today, the discussion of old-growth forest has expanded to an earlier stage of forest called mature forest. Concerns associated with environmental threats led to a broader view of forest management that includes all stages of development. Climate change has spurred more frequent and longer lasting disturbances, such as wildland fire, severe weather, flooding, and insects and disease.

Additional Resources