Fire Effects and Fire Ecology

Pile burning is a common means of disposing the woody residues of logging and for post-harvest site preparation operations, in spite of the practice’s potential negative effects. To examine the long-term implications of this practice we established a 50-year sequence of pile burns within recovering clear cuts in lodgepole pine forests.

Periodic fire is thought to improve whitebark pine (Pinus albicaulis Engelm.) regeneration by reducing competition and creating openings, but the mechanisms by which fire affects seedling establishment are poorly understood.

Questions: Wildfire is a natural disturbance that shapes vegetation characteristics worldwide, while prescribed fire is increasingly used to modify vegetation composition and structure. Due to invasion of many ecosystems by exotic species, a concern of land managers is whether wildfire and prescribed fire alter plant communities in favour of exotics.

Large wildfires of increasing frequency and severity threaten local populations and natural resources and contribute carbon emissions into the earth-climate system.

1. Climate change is likely to shift plant communities towards species from warmer regions, a processtermed ‘thermophilization’. In forests, canopy disturbances such as fire may hasten this processby increasing temperature and moisture stress in the understory, yet little is known about the mechanismsthat might drive such shifts, or the consequences of these processes for plant diversity.2.

The probability of stem survival after fire is strongly influenced by energy allocation to bark because bark thickness affects heat transfer during fire. Greater relative investment in inner bark versus outer bark should also enhance survival because of greater moisture content of inner bark.

Fire is one of the most important natural disturbance processes in the western United States and ecosystems differ markedly with respect to their ecological and evolutionary relationships with fire.

Fire has profound effects on ecosystem properties, but few studies have addressed the effect of repeated burns on soil nutrients, and none have been conducted in cold desert ecosystems where invasion by exotic annual grasses is resulting in greater fire frequency.

Disturbances are integral to ecological systems and affect landscapes across a wide range of scales. The causes of disturbance, the patterns and dynamics they produce, their ecological consequences are major research topics in landscape ecology.

The widespread, native defoliator western spruce budworm (Choristoneura occidentalis Freeman) reduces canopy fuels, which might affect the potential for surface fires to torch (ignite the crowns of individual trees) or crown (spread between tree crowns). However, the effects of defoliation on fire behaviour are poorly understood.