Forestland covers almost half of the state of Oregon (30 million of 62 million acres). As a result, the state of Oregon’s forests has a significant and direct impact on the states economy, as well as the health and well-being of its citizens. In addition to timber production, Oregon’s forests protect freshwater supplies, provide habitat for wildlife, and recreational opportunities for people.
According to the Western Wood Products Association, Oregon leads all other states in timber production. In 2008, Oregon forests produced 4.7 billion board-feet of lumber. This number represents a 23.5% drop from 2007. Higher temperatures will directly affect tree growth, water needs and evapotranspiration, impacts of forest insects, and wildfire. The wholesale value of Oregon’s lumber was nearly 43 percent lower than 2007 at $1.26 billion.
The Climate Leadership Institute (CLI) at the University of Oregon and the Climate Impacts Group (CIG) at the University of Washington have found that the following aspects of climate change will have the greatest impact on Oregon’s forests (CLI, 2007; CIG, 2009):
- Average annual temperatures are projected to increase 2°F by the 2020s and 3°F by the 2040s compared with averages for 1970-1999.
- Average annual precipitation is not currently projected to change significantly, but more winter precipitation will likely fall as rain.
- Atmospheric carbon dioxide concentrations are expected to increase.
As a result of the above likely climatic changes, the CLI and the CIG found that:
- Snowpack is expected to melt earlier in the spring.
- Higher temperatures and altered precipitation regimes will directly affect tree growth, water needs and evapotranspiration, impacts of forest insects, and wildfire. For instance, model results suggest that more water will be available for forests during the winter months (due to a greater percentage of winter precipitation falling as rain, rather than snow, as a result of warmer temperatures). But, research also suggests less water availability for forests in the summer months. For species that are water limited in the summer months, this could negatively impact their growth.
- Climate change could impact the economic contribution of Oregon’s forests both directly (e.g., by affecting rates of tree growth and relative abundance of different tree species) and indirectly (e.g., by changing the magnitude of damage from fire or forest insects).
- The fire season will be extended.
- Due to the CO2 fertilization effect and warming, forests that are not limited by some other resource (water, light, nitrogen, etc) may see increased growth.
- Future fire models suggest a doubling or tripling of area burned in the PNW by the 2080’s. The median regional area burned is projected to increase from about 0.5 millions acres to 0.8 million acres in the 2020’s (a 60% increase), 1.1 million acres in the 2040’s (a 120% increase), and 2.0 million acres (a 300% increase) in the 2080’s.
- Acres burned strongly influence fire suppression costs and may also influence related expenditures such as costs for fire prevention programs. If suppression costs rise in proportion to acres burned—i.e., increase 60% by the 2020s and 120% by the 2040s—state expenditures by the Oregon Department of Forestry (ODF) could rise from $40-64 million at the turn of the century to $64-102 million by the 2020s and $88-141 million by the 2040s (with all figures in constant 2005 dollars). Federal suppression expenditures—by USFS and BLM in an area that includes both Oregon and Washington—could rise from $40-188 million at the turn of the century to $64-301 million by the 2020s and $88- 414 million by the 2040s. A rough estimate allocates approximately 60% of these federal expenditures to Oregon, which translates into a rise in federal expenditures in Oregon from $24-114 million at the turn of the century to $38-180 million by the 2020s and $53-$248 million by the 2040s.
- The full range of economic impacts of wildfire—including lost timber value, lost recreational expenditures, lost ecosystem services such as water purification, and health and environmental costs related to air pollution, hydrology, and other forest changes—could be many times larger than thefire preparedness and control costs described above.
- Climate change could have significant effects (both positive and negative) on the extent and severity of Mountain Pine Beetle (MPB) outbreaks. This is due to a variety of factors including; increased vulnerability of trees when in a water stressed state (which makes them more vulnerable to MPB infestation); and changes in the range where climatic conditions are favorable for the MPB. In all probability, MPB attacks will be more successful and occur at higher elevations.
- Urban forests and the urban-wildland interface may also face growing wildfire risks as temperatures rise. Fires in these areas threaten homes and businesses as well as air qualty, recreation, and quality of life.
- Economic impacts unrelated to wildfires—e.g., from forest insects or changes in tree growth rates attributable to climate change—are unknown and may be either positive or negative. Forest management strategies such as thinning may reduce the severity of fires, but are not likely to reduce the frequency. More research is needed on the ecological effects and economic costs and benefits of thinning.
- Forest-related economic opportunities created by climate change might include carbon sequestration and biomass-based energy production. More research is needed on both of these potential opportunities to determine their economic and ecological feasibility.
- The most economically important timber species in the PNW is the Douglas Fir. Models suggest its range will decrease in the 21st century.
The full text of the CLI publication may be found online . The full text of the CIG publication may be found here.
Climate Impacts Group, University of Washington, 2009: Forest ecosystems, disturbance, and climatic change in Washington State, USA. Chapter 7 in: “ The Washington Climate Change Impacts Assessment: Evaluating Washington’s Future in a Changing Climate.”
Climate Leadership Institute, 2007: “Economic Impacts of Climate Change on Forest Resources in Oregon,” A Preliminary Analysis.
Oregon Dept of Forestry, 2005,: Oregon Forests Report, 22