Insects and Fire

In ponderosa pine forests of western North America, wildfires are becoming more frequent and affecting larger areas, while prescribed fire is increasingly used to reduce fuels and mitigate potential wildfire severity. Both fire types leave trees that initially survive their burn injuries, but will eventually die.

As wildfire activity increases in many regions of the world, it is imperative that we understand how key components of fire‐prone ecosystems respond to spatial variation in fire characteristics.

Understanding the implications of shifts in disturbance regimes for plants and pollinators is essential for successful land management.

Landscape exposure to multiple stressors can pose risks to human health, biodiversity, and ecosystem services. Attempts to study, control, or mitigate these stressors can strain public and private budgets.

Forest disturbance regimes are beginning to show evidence of climate-mediated changes, such as increasing severity of droughts and insect outbreaks. We review the major insects and pathogens affecting the disturbance regime for coastal Douglas-fir forests in western Oregon and Washington State, USA, and ask how future climate changes may influence their role in disturbance ecology.

Across the western United States, the three primary drivers of tree mortality and carbon balance are bark beetles, timber harvest, and wildfire. While these agents of forest change frequently overlap, uncertainty remains regarding their interactions and influence on specific subsequent fire effects such as change in canopy cover.

Prescribed burning is a primary tool for habitat restoration and management in fire-adapted grasslands. Concerns about detrimental effects of burning on butterfly populations, however, can inhibit implementation of treatments.

Western spruce budworm (Choristoneura freemani Razowski; WSBW) is the most significant defoliator of coniferous trees in the western United States. Despite its important influence on Western forests, there are still gaps in our knowledge of WSBW’s impact on fire, and little research has been done on this relationship in high-elevation spruce-fir forests.

Previous studies have suggested that bark beetles and fires can be interacting disturbances, whereby bark beetle–caused tree mortality can alter the risk and severity of subsequent wildland fires.

Climate change is altering the frequency and severity of forest disturbances such as wildfires and bark beetle outbreaks, thereby increasing the potential for sequential disturbances to interact. Interactions can amplify or dampen disturbances, yet the direction and magnitude of future disturbance interactions are difficult to anticipate because underlying mechanisms remain poorly understood.