The decade of fire

Friday, November 16, 2012 - 2:23pm


The extent and severity of fires in the United States during the last decade has increased to more than twice the yearly average area over the previous decade. A major cause of this increase is the accumulated impact of a century or more of fire suppression which has increased forest fuels. The problem is most acute in pine and mixed conifer forests that used to burn frequently. Forest harvesting, and recent climate change have exacerbated the fuel build-up problem increasing the risk of severe fire effects in these ecosystems.

There is considerable scientific debate on whether the severity of fires has increased in montane and upper montane forests in California in recent decades. One way to determine if recent severity patterns are unusual is to compare contemporary severity patterns to a reference landscape that has not experienced fire suppression or land use practices such as logging and to fire behavior modeling experiments.

The Penn State Department of Geography is conducting several research projects that are focused on identifying the causes of fire severity variation by comparing the spatial patterns of fire severity in the late nineteenth century with patterns in the late twentieth and early twenty-first century, and with spatially explicit fire modeling experiments. We are particularly interested in the effects of topography on patterns of fire severity. Causes of variation in fire severity include daily weather conditions, fire suppression and fuel build up, other past management action, and climate. High fire severity patch location could be stochastic, or fixed in space by topographic influences. However, quantifying the effect of topography on observed patterns of fire severity patches is difficult because fires are stochastic events burning through dynamic and heterogeneous fuel, weather, and historic management conditions.   

Neutral models will allow this research to hold these confounding factors constant to assess the interaction of topography on predicted fire intensity. Specific objectives are to:

1) identify and compare the observed fire effects of recent fires with estimates of fire behavior derived  from before and after fire measurements of vegetation and fuels;

2) identify landscape patterns of fire severity using remote sensing and compare the severity to simulations of landscape fire behavior using the pre-fire vegetation and fuels data as input to the model;

3) compare the spatial patterns of fire severity and simulated fire intensity for recent fires to spatial patterns of pre-fire suppression period fire frequency and fire severity; and

4)  identify additional weather, topographic, and vegetation variables that contributed to the severity patterns.


 Read more about the current research being done by the Vegetation Dynamics Laboratory.