Turner, David: Oregon State University (Project Lead)
Project Funding:
2012 - 2015
NRA: 2011 NASA: Terrestrial Ecology
Funded by NASA
Abstract:
Large tracts of forestland in the Northwestern U.S. are subject to recurrent clear-cut harvest, thinning, variable intensity fire, and insect outbreak. These disturbances have significant impacts on the local and regional carbon balance. The Northwest forests also offer the opportunity for mitigation of climate change by acting as carbon sinks through positive net ecosystem production (NEP, the balance of net primary production and heterotrophic respiration) in undisturbed stands. The proposed research will examine decadal trends in climate, NEP, and net ecosystem carbon exchange (NEP - fire emissions - logging removals) in the Pacific Northwest region using a combination of time series Landsat data and ecosystem carbon cycle modeling.
Our objectives include 1) addressing science questions related to understanding the spatial and temporal patterns in forest disturbance and carbon flux, 2) addressing policy relevant questions about the relative magnitude of fire emissions and background forest carbon sequestration, and 3) developing maps of carbon stocks and flux with well characterized uncertainty that can be used in uncertainty assessments of carbon cycle studies based on alternative scaling approaches.
Our study area provides excellent contrasts over which to characterize ¿impacts to and vulnerability of terrestrial ecosystems and critical terrestrial components of the global carbon cycle to global environmental change¿. The study region (WA, OR, ID, western MT) extends across a broad climatic gradient from cool, mesic coastal forests used primarily for wood production, to drier forests on the east side of the Cascade Mountains, and into the Northern Rocky Mountains with its more continental climate regime and higher incidence of insect outbreaks. Our study period (1985-2010) includes a wide range of interannual climate variability, notably 2002 when the Biscuit Fire burned over 200,000 ha in Southwestern Oregon and 2010, a strong La Niña year with virtually no wild fires in the region.
Our approach relies on Landsat-based time series analysis of forest disturbance. It will permit attribution of disturbance type (fire, insects, and harvest) and quantification of disturbance intensity. We will use the Landsat-based disturbance information as input to a well-established modeling infrastructure for simulating regional carbon flux based on the Biome-BGC model. For this study, we will add algorithms to Biome-BGC that simulate partial disturbances, notably forest thinning, which is becoming more prevalent in the PNW region. Our approach will make extensive use of plot scale and aggregated USDA Forest Service Forest Inventory and Analysis (FIA) data for model parameterization and uncertainty assessment.
Because quantifying terrestrial carbon sources and sinks is of policy significance in relation to addressing the climate change issue, this research contributes to the NASA strategic goal of advancing scientific understanding of Earth and meeting societal needs. It will further the NASA research objective of improving carbon cycle models, and results will inform the on-going assessments of the state of the carbon cycle.
Publications:
Turner, D. P., Ritts, W. D., Kennedy, R. E., Gray, A. N., Yang, Z. 2016. Regional carbon cycle responses to 25 years of variation in climate and disturbance in the US Pacific Northwest. Regional Environmental Change. 16(8), 2345-2355. DOI: 10.1007/s10113-016-0956-9
Turner, D. P., Ritts, W. D., Kennedy, R. E., Gray, A. N., Yang, Z. 2015. Effects of harvest, fire, and pest/pathogen disturbances on the West Cascades ecoregion carbon balance. Carbon Balance and Management. 10(1). DOI: 10.1186/s13021-015-0022-9
More details may be found in the following project profile(s):
