Wildfire and Bark Beetles in Subalpine Forests

 Extensive drought and warmer temperatures have been linked to increased area burned by wildfire and synchronous outbreaks of native bark beetles, causing widespread tree mortality in US western forests over the last 15 years. Since the 1970s, the average annual number of fires over 40 hectares has doubled in Rocky Mountain states, and seven of the largest fire years have occurred since 2000.  Since the late 1990s, 19 million hectares have been affected by tree mortality from bark beetles across the western US, with about half that area affected by mountain pine beetles. Current legislation and management policies aimed at mitigating fire risk and severity across the western US cite extensive bark beetle damage as justification for actively salvaging dead trees or thinning green forests yet unaffected by bark beetles. However, little is conclusively known about if, how, or when bark beetle-caused tree mortality increases the risk or severity of subsequent wildfire in subalpine forests. We are conducting a large-scale analysis of the observed effects of mountain pine beetle-mortality on fire occurrence and severity across the western forest landscape. We are also developing a synthesis of key disturbance interactions in subalpine forests that considers linkages between fire and bark beetles, where one disturbance alters the probability or severity of another, and 2) compound effectsof fire and bark beetles, where linked disturbances affect successional trajectories and capacity of the forest system to recover.

Spatial assessment of fuel treatments across the western US

In 2000 the U.S. National Fire Plan (NFP) established a long-term fuels reduction program to reduce the risks of catastrophic wildland fire to communities and to restore forests and rangelands subject to fuels build-up due to fire suppression. Policy makers and natural resource managers are assigning substantial ecological and economic benefits to these treatments, such as reducing wildfire risk to residential communities in the wildland-urban interface, deterring adverse ecological impacts of uncharacteristically severe wildfire and reducing high costs of wildfire suppression. Although over 11 million hectares have been treated under this policy, there has been little analysis of the location, character and scope of these widespread management activities, nor an evaluation of the extent to which treatment locations are consistent with ecological-restoration or fire-mitigation goals. We conducted a series of analyses to evaluate whether treatments are located in areas: 1) near the wildland-urban interface (WUI), 2) where the need for structural restoration is expected to be high and 3) that subsequently burn by wildfire or have high probability of wildfire occurrence.

Wildfire and the Wildland Urban Interface


Continued residential development in fire-prone landscapes, combined with a changing climate, requires a more sustainable coexistence with wildfire in western landscapes. This research explores the relationship between forest management, fire risk, ecological integrity and human safety in the wildland-urban interface (WUI). In the Colorado Front Range, we developed spatially explicit baseline studies that evaluate how fire exclusion affected wildfire behavior and fire risk to people and property across the WUI landscape. Building upon these baseline assessments, we considered forest management scenarios to reduce fire risk while also protecting ecological integrity across a heterogeneous wildland-urban interface. More broadly, we are assessing science and policy solutions to help promote more fire-resilient ecosystems and fire-adapted residential communities across the West.