Fire research of the Southwest Watershed Science Team

The Southwest Watershed Science Team of the Air, Water, Aquatic Ecosystems Program, Rocky Mountain Research Station, has been involved in studies to determine the soil and watershed effects of wildfires and prescribed fires since 2000. This effort has been funded by the National Fire Plan Program of the USDA Forest Service. This web site displays some of the past and current fire-related activities of the Team.

Background and Importance

Knowledge of fire effects has risen in importance to land managers because fire, as a disturbance process, is an integral part of the concept of ecosystem management and restoration ecology. Fire initiates changes in ecosystems that affect the composition, structure, and patterns of vegetation on the landscape. It also affects the soil and water resources of ecosystems that are critical to overall functions and processes.

Fire is a dynamic process, predictable but uncertain, that varies over time and landscape space. It has shaped plant communities for as long as vegetation and lightning have existed on earth (Pyne 1982). Recycling of carbon and nutrients depends on biological decomposition and fire. In regions where decay is constrained either by dry or cold climates or saturated (in other words, anaerobic) conditions, fire plays a dominant role in recycling organic matter (DeBano and others 1998).

Fire Effects on Soil

Soil is the unconsolidated, variable-thickness layer of mineral and organic matter on the Earth's surface that forms the interface between the geosphere and the atmosphere. It has formed as a result of physical, chemical, and biological processes functioning simultaneously on geologic parent material over long periods (Jenny 1941, Singer and Munns 1996 - Soils: An Introduction. Third Edition). Soil is formed where there is continual interaction between the soil system and the biotic (faunal and floral), climatic (atmospheric and hydrologic), and topographic components of the environment.

Soil interrelates with other ecosystem resources in several ways. It supplies air, water, nutrients, and mechanical support for the sustenance of plants. Soil also receives and processes rainfall. By doing so, it partly determines how much becomes surface runoff, and how much is stored for delivery slowly from upstream slopes to channels where it becomes streamflow, and by how much is stored and used for soil processes (for example, transpiration, leaching, and so forth). When the infiltration capacity of the soil for rainfall is exceeded, organic and inorganic soil particles are eroded from the soil surface and become a major source of sediment, nutrients, and pollutants in streams that affect water quality.

The fire-related changes associated with different severities of burn produce diverse responses in the water, soil, floral, and faunal components of the burned ecosystems because of the interdependency between fire severity and ecosystem response. Both immediate and long-term responses to fire occur. Fire can produce a wide range of changes in landscape appearance (image at right; DeBano and others 1998).

Immediate effects also occur as a result of the release of chemicals in the ash created by combustion of biomass. The response of biological components (soil microorganisms and ecosystem vegetation) to these changes is both dramatic and rapid. Another immediate effect of fire is the release of gases and other air pollutants by the combustion of biomass and soil organic matter. Air quality in large-scale airsheds can be affected during and following fires (Hardy and others 2001, Sandberg and others 2002).

The long-term fire effects on soils and water are usually subtle, can persist for years following the fire, or be permanent as occurs when cultural resources are damaged (DeBano and others 1998). Other long-term fire effects arise from the relationships between fire, soils, hydrology, nutrient cycling, and site productivity (Neary and others 1999).

Fire Research by the Team

	Fire and fire-surrogate study More information
	Schultz Fire 2010 More information
	Cascabel Fire 2008 More information
	Rodeo-Chediski Fire 2002 More information
Photo used with permission from www.wildlandfire.com.	Coon Creek Fire 2000
Go to the Southwest Watershed Science Team home page.