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Monitoring surface and canopy fuel conditions after stand-replacing disturbance events in northern Rocky Mountain ecosystems.

It is generally assumed that insect and disease epidemics, such as those caused by the mountain pine beetle, predispose damaged forests to high fire danger by creating highly flammable fuel conditions. While this may certainly be true in some forests, these dangerous fuel conditions many only occur for a short time when evaluated at a landscape level. Others feel these epidemics may cause high surface fuel loadings when the dead material from dead trees falls to the ground. These high fuel loadings may result in abnormally severe fires. This study will evaluate, through intensive field collections and simulation modeling, the effect that exogenous disturbance events, namely fire and beetles, have on future fire hazard and risk. We will measure surface fuel deposition and decomposition rates for eleven forest types after wildfire events and after beetle epidemics to quantitatively describe fuel dynamics to ultimately estimate resultant fire behavior in heavy mortality stands for up to 10 years after the disturbance. Fuel deposition will be measured using semi-annual collections of fallen biomass sorted into six fuel components (fallen foliage, twigs, branches, large branches, logs, and all other material). This litterfall will be collected using a network of seven, one meter square litter traps installed on plots established on seven sites across the northern Rocky Mountains USA. We will also measure decomposition using litter bags installed in one sets of five bags for three surface woody fuel components and monitor biomass loss from the bags each year for 5-10 years. We will also measure stand and fuel characteristics of the plot using FIREMON techniques at the beginning, and every year till the end of the study. We will last quantify fire behavior for each plot using collected or measured tree and fuels data, local weather summaries coupled to the BehavePlus fire model and the NEXUS crown fire model. We will summarize and report fuel deposition and decomposition rates in these disturbed stands over the 10 year period and the describe fire hazard in these stands for each of the 10 years.

The project has one primary objective and a number of specific objectives:

  • Determine if recently disturbed stands in the northern Rocky Mountains have high fire hazard

This objective will be achieved using the following steps described as sub-objectives;

  • Measure the litterfall and decomposition rates of major fuel components across major forest types in the northern Rocky Mountains after a major disturbance event for 10 years
  • Measure stand conditions at the beginning, and every year to year 10 of this study
  • Implement findings in ecosystem models containing explicit simulations of fuels dynamics
  • Model fire behavior and fuel conditions in these stands for the decade after the disturbance events using the collected stand data
  • Model fire behavior and fuel conditions after the 10 years of this study using ecosystem models parameterized using the data from this study

The audience for this effort is managers and researchers interested in describing and sampling fuels after stand-replacement disturbances for future fire behavior and effects prediction. This research may lead to new methods of prioritizing fuel treatments after major insect, disease, or fire events and it will provide important parameters and values for fuel sampling efforts.

Photo: One of the littertraps installed at a FUELDIST monitoring site

Photo: Fuel distribution litter trap
Modified: Jun 11, 2014

Select Publications & Products

Keane, R.E. 2008. Biophysical controls on surface fuel litterfall and decomposition in the northern Rocky Mountains, USA. CanadianJournalForest Research 38:1431-1445

Keane, Robert E. 2008. Surface fuel litterfall and decomposition in the northern Rocky Mountains, USA. USDA Forest Service Rocky Mountain Research Station Research Paper RMRS-RP-70. 22 pages