Future projections of U.S. forest succession classes on federal lands

Changing climate conditions, wildfires, and tree harvesting could affect the amount of mature and old-growth forests in the United States. We used a stochastic modeling system to project future areal extents of mature and old-growth forests on National Forest System (NFS) and Bureau of Land Management (BLM) land across the conterminous United States, and to assess threats to these forests under a variety of socioeconomic and climate futures. The data included in this package contain estimates and projections, from 2020 to 2070, of forest area and volume by forest successional class (old growth, mature, and younger) for 20 futures, which are combinations of four socioeconomic scenarios and five global climate models. Estimates of area, tree volume, fire mortality, and harvest removals are provided for each Resources Planning Act (RPA) region. Additionally, estimates of current and future area of mature and old-growth by Forest Inventory and Analysis (FIA) forest type group are included. For each of the 20 futures in the regional and forest type group summaries, 100 future realizations from the stochastic modeling system are included, allowing for the quantification of uncertainty. Finally, data on initial sampling errors by forest successional class and forest type group are included. It is important to note that estimates by forest type group only include the twelve largest forest type groups (by area in 2020).These data were developed to assess the effects of changing climate and socioeconomic factors on the projected amount of mature and old-growth forests on federal forests in the United States.For more information about this study and these data, see Costanza et al. (accepted, 2025). These data were published on 08/04/2025. On 08/13/2025, the R code included in this package was updated to correct some of the legends and other updates related to the figures generated.