5. What are the effects of landscape fires?

Landscape fires of both natural and anthropogenic origin have known biotic and abiotic effects on ecosystem properties and the environment. The biotic effects of fire include changes in vegetation and subsequent impacts on wildlife. Abiotic effects include changes in soil properties, nutrient cycling and air quality. The health and security of human populations are also impacted.
Effects of fire on plants: The primary effect of fire on plants is death or damage to living cells. Plant cell death, regardless of species, occurs at 60°C. At somewhat lower temperatures, more time is required to kill plant tissues. Fire can have also positive effects on plants. Some plants rely on fire to release their seeds, eliminate competition or supply a layer of nutrient-rich ash. For example, cones of jack pine tree can hang for years without opening and only the fire melts the resin, allowing the cones to open up and release the seeds.
Effects of fire on wildlife: Fire can have both positive and negative effects on wildlife. The specific effects depend upon the frequency, intensity, severity, and season of burning, as well as the habitat requirements of wildlife. Fire effects on wildlife are mainly indirect through changes in food and cover. Fires can create open space and stimulate the growth palatable grass and shoots, thereby improving conditions for deer and other wildlife.
Effects of fire on soil: Fire affects the chemical, biological, and physical properties of soil. Specific effects of fire on soil may vary greatly depending on the fire intensity, ambient temperature, vegetation type, soil type, and soil moisture. These factors can produce either positive or negative effects. The specific effects of fire on soil are largely determined by fire intensity. Low-intensity fires have little adverse effect on soil properties. In fact, they may even improve the availability of nutrients contained in the ash. Severe fires may potentially alter soil physical properties by consuming soil organic matter. This can result in soil erosion, surface run-off and flood generation.
Effects of fire on air quality: Landscape fires have potentially negative effects on air quality. All landscape fires emit carbon monoxide, sulfur dioxide, nitrogen dioxide, ozone, and particulate matter. Radioactively active trace gas and particle emissions impact biogeochemical cycles and thus the global atmosphere and climate.
Effects of fire on human health: Smoke can have negative short- and long-term health effects. High smoke concentrations can cause a serious health risk for people with respiratory illnesses and especially for children and elderly people. Firefighters who are exposed to high smoke concentrations often suffer eye and respiratory system irritation. Continued exposure to high concentrations of carbon monoxide in the combustion zone can result in impaired alertness and judgment. Fine carbon particles, which were inhaled by people and deposited in their lungs may cause cancer.

People wearing masks to filter out smoke from landscape fires surrounding a residential area, Greece, Summer 2007. Source: N. Giakoumidis.