title: Effects of harvest, fire, and pest/pathogen disturbances on the West Cascades ecoregion carbon balance.
abstract: BACKGROUND
  Disturbance is a key influence on forest carbon dynamics, but the complexity of spatial and temporal patterns in forest disturbance makes it difficult to quantify their impacts on carbon flux over broad spatial domains. Here we used a time series of Landsat remote sensing images and a climate-driven carbon cycle process model to evaluate carbon fluxes at the ecoregion scale in western Oregon.
  
  
  RESULTS
  Thirteen percent of total forest area in the West Cascades ecoregion was disturbed during the reference interval (1991-2010). The disturbance regime was dominated by harvesting (59 % of all area disturbed), with lower levels of fire (23 %), and pest/pathogen mortality (18 %). Ecoregion total Net Ecosystem Production was positive (a carbon sink) in all years, with greater carbon uptake in relatively cool years. Localized carbon source areas were associated with recent harvests and fire. Net Ecosystem Exchange (including direct fire emissions) showed greater interannual variation and became negative (a source) in the highest fire years. Net Ecosystem Carbon Balance (i.e. change in carbon stocks) was more positive on public that private forestland, because of a lower disturbance rate, and more positive in the decade of the 1990s than in the warmer and drier 2000s because of lower net ecosystem production and higher direct fire emissions in the 2000s.
  
  
  CONCLUSIONS
  Despite recurrent disturbances, the West Cascades ecoregion has maintained a positive carbon balance in recent decades. The high degree of spatial and temporal resolution in these simulations permits improved attribution of regional carbon sources and sinks.
authors.affiliation: Department of Forest Ecosystems and Society, Oregon State University, 97331 Corvallis, OR USA.
authors.forename: David P
authors.initials: DP
authors.lastname: Turner
authors.affiliation: Department of Forest Ecosystems and Society, Oregon State University, 97331 Corvallis, OR USA.
authors.forename: William D
authors.initials: WD
authors.lastname: Ritts
authors.affiliation: College of Earth, Ocean, and Atmospheric Sciences, Oregon State University, 97331 Corvallis, OR USA.
authors.forename: Robert E
authors.initials: RE
authors.lastname: Kennedy
authors.affiliation: USDA Forest Service, Pacific Northwest Station, 97331 Corvallis, OR USA.
authors.forename: Andrew N
authors.initials: AN
authors.lastname: Gray
authors.affiliation: Department of Forest Ecosystems and Society, Oregon State University, 97331 Corvallis, OR USA.
authors.forename: Zhiqiang
authors.initials: Z
authors.lastname: Yang
keywords: Carbon; Disturbance; Forests; Net ecosystem carbon balance; Net ecosystem exchange; Net ecosystem production; West Cascades ecoregion