1. 2015 RPA Update: Forest Carbon Projections for the United States
David Wear
John Coulston
USDA Forest Service, Research and Development
Southern Research Station
RPA/FIA

2. The RPA Assessment
The Forest and Rangeland Renewable Resources Planning Act of 1974 mandates a national report (RPA Assessment) on the conditions and trends of renewable resources on all forest and rangelands every ten years.
The RPA Assessment provides a snapshot of current U.S. forest and rangeland conditions and trends; identifies drivers of change; and projects 50 years into the future ( for the Update).
Provides authoritative outlook for America’s forests and rangelands.

3. Resources Evaluated Land Resources Forest Resources Urban Forests
The RPA Assessment includes analyses of the following resources, as well as the potential effects of climate change:
Land Resources
Forest Resources
Urban Forests
Forest Products
Forest Carbon
Rangeland Resources
Water Resources
Wildlife, Fish, and Biodiversity
Outdoor Recreation

4. Evolution of Projections
From 2010 RPA Assessment to USDA Integrated Projections and 2015 RPA update
New forest carbon inventory system
Full consistency between inventory and projection
Supported by FIA continuous/annual forest inventory
Revised land use projections
Accounting for recession/coordination within USDA
Land development deferred
Decomposition (attribution) of changes
Land use, disturbance, …

5. Land based carbon change
Other rural land (crops, range,…)
Developed land
Forest land
CFF
COD
COO
COF
CDD
CFO
CFD
Inventories had lumped land use transfers and sequestration (Cff)
Separating these elements is essential for evaluating how to increase forest C
Goal: isolate Cff

6. Forest Carbon
Net forest sequestration ranged from 112 to 133 Tg per year between 1990 and 2015 and averaged 122 Tg per year.
Forest area increase accounted for about 41 percent of the total forest carbon stock change.

7. C dynamics (South)
High degree of detail is included in the change dynamics.
The new FIA inventory system allows for this enhanced monitoring, projections, and policy analysis.

8. Forest Carbon
Forests in the eastern United States account for over 60 percent of U.S. forest carbon stocks and 80 percent of net forest carbon sequestration.

9. Projection methods Simulate transition of all forest inventory plots
South; North; Great Plains
Rockies; Pacific Northwest; Alaska
Simulate transition of all forest inventory plots
Based on empirical evidence from measured inventory transitions
Forest aging
Land use change
Timber harvests
Fire
Other disturbances
Simulate transition of forest inventory aggregates
Based on empirical evidence from split panels or single set of measured plots
Forest aging
Land use change
Timber harvests
Fire
Other disturbances
A regionally specific modeling approach accounts for differences in aging and disturbance dynamics.
Projections of forest carbon link biological forest dynamics with socioeconomic dynamics, affecting land use and timber harvesting.

10. Projections: Land use assumptions
Projections were driven by socioeconomic scenarios designed by a USDA team for coordinated analysis of economic activity affecting all lands.
For the Reference scenario, observed forest area was assumed to continue growing for the next decade, level off, and then begin to fall after 2030.
Area of forest land use from the U.S. National Greenhouse Gas Inventory, and projections for three scenarios,

11. Developed land

12. Projected US forest carbon (three scenarios)
Cff plus land use transfers
Land use transfer
Cff
Forests are projected to remain an important sink of atmospheric carbon throughout the projection period.
The total forest carbon inventory increases at historical rates between 2015 and and then at a decreasing rate that approaches zero by 2060 due to land use transfers.
After accounting for land use transfers, the amount of forest sequestration of atmospheric carbon declines very gradually during the projection period.
Sequestration changes gradually; transfers rapidly
Gradual decline in sequestration from atmosphere

13. Projections: Regional forest carbon
Western regions lose more sequestration than East
East shifts to about 90% of sequestration by 2040
Rockies go quickly to zero / C source by 2025

14. Forest area by ownership and age

15. Harvest Wood Products Inventory Projections
Projections are sensitive to:
Population change
Income change
Associated changes in housing starts
Carbon stored in durable wood products and solid waste disposal are tracked separately
Relationship between cutting and production
Relationship between production and product
Additions
HWP
Pool

16. Projections: Harvested wood products carbon
The amount of wood products carbon declined to historic lows during the recent economic downturn.
Wood products carbon storage rates have recovered and are expected to increase to historic averages in future decades.
Recovery and future depends strongly on recovery of housing demand.

17. Projections: Total forest sector
Forest Sequestration
plus land use transfers
Forest sequestration plus wood products C
Forest
sequestration
Total forest sector carbon sequestration—the sum of forest sequestration and changes in HWP carbon storage—increases from 2005 to 2020 and then declines very gradually.
Estimates of (1) changes in forest carbon stocks, (2) net forest carbon sequestration, and (3) forest sector sequestration of carbon measured in Tg carbon/year for the Reference scenario,

18. Key questions: Land Use

19. Key question: Land Use Population growth and land development
projected to continue
Slowed during recession; returning with recovery
Agriculture--forest dynamic
Led to strong net gain in forests since 1980
Gains have dampened since 2000
Projections: from stable to net losses of forests in next decade

20. Implications
U.S. forests continue to sequester significant amounts of atmospheric carbon
Isolating carbon sequestration requires accounting of transfers among land uses and to harvested wood products.
Rates of carbon sequestration vary strongly across regions: eastern regions account for 80 percent of historical sequestration and as much as 90 percent of projected sequestration.
Projections indicate an increase then gradual slowing of sequestration over time: sequestration under a reference scenario peaks in 2020 at 159 Tg/year and then declines to 122 Tg/year in 2060.

21. Conclusions
Protecting the sink strength and the stock requires first maintaining land base
Intensive monitoring is indicated
Potential rapid change in position due to land use
Uncertainty regarding climate effects
Percent contribution of harvested wood products increases in future
Strong links to market activities

22. Ongoing work / Remaining ?’s
Steady enhancement of methods
Growing FIA data library improves forecasts and projections
Especially important for the West where measurement frequency is lower
Enhancing the land use projections FIA-RPA
Especially in the East where land use dynamics are most substantial
Climate change effects RPA
Shifting types / productivity / land uses
Harvested wood products carbon models FIA-TPO-RPA
Enhancing links to products markets analysis

23. Thanks for listening