America's Future Forests: The 2020 Resources Planning Act Assessment

In the Land Resources chapter, researchers summarize recent land use and land cover trends across the conterminous U.S. and present future projections to 2070 based on RPA scenarios. The team evaluates recent land cover changes and their impact on forest fragmentation, summarizes land use projections under future scenarios, and evaluates projected changes in impervious and tree covers and landscape patterns. The chapter also provides more information about the condition and health of forests, rangeland, and other specific land resources.

• Developed land use includes everything from a house to a manufacturing facility and has been expanding for decades. While expansion is projected to continue, the rate has slowed. The projected increase in developed land use ranges between 42% and 58% by 2070 across the four RPA scenarios, from an estimated 97.7 million acres in 2020. These increases in developed land occur at the expense of all other land uses including forests.
• Across the country, forest land area increased slightly over the past decades, mostly because of declines in pasture and crop land areas. This trend is expected to shift to decreasing forest area under all scenarios, although at lower rates than projected by the 2010 Assessment.
• In the Southeast, forest fragmentation continues, but the rate has slowed. Most forest lands are part of more natural landscapes, but an increasing proportion of forest is expected to be in or near towns, farms, and other types of developed use. These landscapes are known as interface landscapes and could expose forests to more frequent invasive species.
• The assessment reports that economic and regional factors tend to be more important drivers of land use area changes than changes in climatic conditions.

In the chapter on Disturbances to Forests and Rangelands, researchers assess status and trends of abiotic and biotic disturbance agents, including fire, drought, insects and disease, and nonnative invasive plants. Along with those agents, they summarize some forest management actions— prescribed burning and removals—that can be classified as disturbances because they alter environmental conditions and lead to changes in forest structure or community composition even as they can contribute to long-term forest resilience. 

• The average annual area burned by large wildfires since 2000 is more than double the pre-2000 average.
• In forests, prescribed fires conducted for management have been most prevalent in the South Region.
• Drought exposure for forests and rangelands is expected to increase by 2070, and forest and rangeland ecosystems in the Southwest are expected to experience the most substantial increases. Forest and rangeland exposure to drought is expected to intensify over this century, particularly if the climate tends toward the hot, dry, or middle climate futures.
• In the South, the highest rates of invasion by nonnative plants occur near agricultural or developed land uses.
• The longleaf-slash pine forest type that occurs in the southeastern U.S. is projected to face low to moderate drought exposure. In addition, longleaf pine (Pinus palustris) is likely more drought tolerant than other tree species, which could make this forest type relatively resilient to future drought exposure, despite a projected increase in exposure by mid-century. The likely drought resilience of longleaf pines is one reason why forest restoration in the Southeast has emphasized creating and maintaining a prominent longleaf pine component as a strategy for climate adaptation.

The Forest Resources chapter summarizes recent and projected trends in forest resources – the area of forested land, timber volumes, and historic and future trends in forest carbon. This chapter also covers trends in forest ownership based on the Forest Inventory and Analysis National Woodland Owner Survey. 

• Despite increases in forest area from 1977 to 2017, several forest types have decreased in extent, including oak-pine forest types in the East. Some forest types are expected to lose area due to forest loss, conversion to planted pine following harvest, climate, and succession. In the South, these types include oak-gum-cypress forests.
• Under futures that include high roundwood demand and net forest loss, the forest ecosystem is projected to become a net source of CO ₂ by 2070, a finding consistent with previous research .
• Aboveground biomass carbon density (carbon per unit area) is projected to increase by 17% to 25% over 2020 densities by 2070, while annual carbon stock change is projected to decrease, indicating increasing carbon saturation of U.S. forests.
• There are an estimated 9.6 million family forest ownerships across the U.S., and they control more forest land than any other ownership category. In the South, more than half of the forest land (56%) is owned by family forest owners, most of whom have relatively small land holdings.
• The U.S. South is projected to remain the dominant timber producing region in the world, producing around 10% of total industrial roundwood under all RPA scenarios.

Future Scenarios 

This chapter describes the approach used to develop the four scenarios in the report. The scenarios depict coherent interdependent futures for global and U.S. population dynamics, socioeconomic factors, and climate change. All resource areas (e.g., forests, water, recreation, and wildlife) use the same set of scenarios or a subset (e.g., climate only) to define a plausible range of natural resource availability and condition over a 50-year period, establishing a consistent and coordinated approach.

• Claire B. O’Dea, USDA Forest Service, Washington Office Research & Development
• Linda L. Langner, USDA Forest Service, Washington Office Research & Development (retired)
• Linda A. Joyce, USDA Forest Service, Rocky Mountain Research Station (emeritus)
• Jeffrey P. Prestemon, USDA Forest Service, Southern Research Station
• David N. Wear, USDA Forest Service, Southern Research Station (retired)

Forest Products 

This chapter describes recent trends in global and U.S. forest product consumption, production, and net trade. It also explores economic projections of production, consumption, net trade, timber harvest levels, and timber prices, as influenced by four future scenarios regarding economic and population growth and changing biomass energy demand through 2070.

• Craig M.T. Johnston, Consulting Economist
• Jinggang Guo, Louisiana State University
• Jeffrey P. Prestemon, USDA Forest Service, Southern Research Station

Outdoor Recreation and Wilderness 

Recreation is a primary means through which people interact with rivers, forests, and other natural resources. In this chapter, the researchers describe current recreation opportunities in the U.S. and how future population and land use changes may influence them, as well as recent patterns and projected patterns under the four future scenarios. 

• Eric M. White, USDA Forest Service, Pacific Northwest Research Station
• Ashley E. Askew, University of Georgia
• J.M. Bowker, USDA Forest Service, Southern Research Station (retired)