Fire Ecology & Research

Fire Ecology is the study of interactions between fire and living organisms and their environment. Fire ecologists may study the effects of fire on plants, soil, animals, water quality, and more. They may also take a bigger picture approach and study how fire affects multiple aspects of an ecosystem, since organisms are connected to each other and to their environment. Scientists with an interest in longer term patterns of fire occurrence may study the history of fire through research involving tree rings, or model fire spread under varying conditions. These parks have a rich history of monitoring and research that has informed the fire management program.

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The Fire Monitoring Program collects data before, during, and after prescribed burns or lightning-caused fires to characterize the effects of fire on vegetation and fuels. This information helps managers determine if burn objectives are met, and increases our understanding of fire's ecological role in these parks.


Fire Monitoring

Fire Monitor wearing nomex fire shirt and hard hat examines handheld instrument to read relative humidity near a fire.
A Fire Monitor collects data about weather near a park prescribed burn. Here she is taking relative humidity, and other data collected include wind direction, wind speed, and temperature.

NPS photo

The parks’ Fire Monitoring Program began in 1982. Its purpose is to help park managers understand if the decisions we have made managing fires are leading to outcomes that are good for forest and ecosystem health.

The fire monitoring program focuses primarily on prescribed burns and lightning-caused fires that are managed for the benefit of these fire-adapted forests. However, occasionally monitoring occurs for other management actions that reduce fuel amounts, such as tree thinning. Monitoring includes the following components:

Three Fire Monitors in a pine forest prepare to weigh fuel moisture samples - different sizes and diameters of wood that are used to measure changes in fuel moisture over time.
The different pieces of wood in this photo are weighed to monitor changes in fuel moisture over time. Increasing weight indicates higher fuel moisture. The fuel moisture is an important variable used in predicting fire behavior.

NPS photo

Environmental and Fire Conditions

Fire Monitors collect data on current weather conditions and note local landscape characteristics such as slope and aspect. They also pay attention to forecasted weather, important to predicting potential changes in fire activity. In addition to weather, they record what the fire is doing (this is known as fire behavior). Fire behavior may include the rate and direction of fire spread, the type and amount of fuel (live and dead vegetation) burning, and smoke movement and dispersal. Detailed information is collected on the amount of moisture in different sizes of logs and sticks (called fuel moisture). These data help to predict what the fire will do next, and to interpret results of other monitoring that tracks fire effects on vegetation and fuels.

Several fire monitoring field crew members in shrub vegetation with fire burning in distance, use meter tapes to install vegetation and fuels monitoring plots.
Four fire effects monitoring crew members use meter tapes to install a standard-sized plot for recording data on vegetation and fuels pre-fire. Note the fire in background expected to burn this area.

NPS photo

Vegetation and Fuels

Vegetation is very diverse in these parks due to the steep elevation gradient and varieties of terrain. To characterize vegetation for fire and other management needs, we map it across the landscape, identifying different types of vegetation (such as ponderosa pine forest, giant sequoia/mixed conifer forest, or blue oak woodland). In fire management, the vegetation types that have missed many natural fires due to fire suppression can be identified from fire history research and local knowledge. Managers and scientists develop vegetation and ground fuel target conditions for these vegetation types. Prescribed fire, and occasionally tree thinning, are used to achieve these targets in selected areas. The targets include specific numeric ranges of densities and species composition of trees, amounts of ground fuels, distribution of fuels, and distribution of open areas or patches in the forest canopy.

Vegetation and fuels monitoring is essential to determining if objectives have been achieved, and also may identify unexpected outcomes of a fire.

Fire burning along the ground below giant sequoias
The fire regime in giant sequoia-mixed conifer forests includes fire burning in surface fuels on the ground in most areas and some patches of higher severity fire that goes up into tree canopies and kills some trees. This patchy high-severity fire opens up gaps where young trees can grow.

NPS photo / Anthony Caprio

Fire Regime

A fire regime is the naturally-occurring pattern of fire in a particular vegetation type or specific location. The characteristics of a fire regime include:

  • Fire return interval (how often fire burns)

  • Season of occurrence (when it burns)

  • Fire size and pattern

  • Fire type (burning on ground surface below trees, or crown fires that burn from tree to tree in branches and treetops)

  • Fire intensity (the quantity of heat produced)

  • Fire severity (level of damage to what is affected by fire)

Park managers monitor fire regimes to understand how fire burned in various vegetation types in the past and to measure the success of the program’s efforts at restoring and maintaining fire as a process. Lower elevation mixed-conifer forests had frequent fire in the past, and fire suppression resulted in many missed fires in this vegetation type. In contrast, higher elevation forests with infrequent past fire have remained closer to their historic fire regime. Understanding fire history and tracking recent fire occurrence allows managers to identify areas that most need restoration of fire. It also helps them evaluate how effective the fire management program has been in re-establishing fire as a process.

Two men kneel near a square study plot collecting fuels and vegetation data
Maurice Zardus (left), Wildlife Biologist, and Bruce Kilgore, Research Biologist, collect fuels and vegetation data at the first prescribed burn site for Sequoia and Kings Canyon National Parks, 1970.

NPS photo

Fire Research

Bruce Kilgore, an early research scientist in these parks, studied fire history and fire effects in giant sequoia groves and mixed-conifer forests in the late 1960s and early 1970s. His work established the foundation for the prescribed fire program. He worked closely with park managers to collect vegetation, fuels, and fire history data and conduct the first prescribed burn in the Rattlesnake Creek area of Kings Canyon National Park. In the decades that followed, many scientists from within the National Park Service as well as from the U.S. Geological Survey, universities, and other organizations contributed new information to the fire program through a variety of research projects.

Two maps of Sequoia & Kings Canyon National Parks - left side one highlights areas of lower frequency fire, and right side map shows areas of higher frequency fire
Maps of Sequoia and Kings Canyon National Parks showing the distribution of vegetation with a low or very low fire frequency (left) and with a very high fire frequency (right). Fire frequency is reconstructed from tree-ring data, and mapped vegetation.

Image from paper: Caprio, A. C. and P. Lineback. 2002. Pre-Twentieth Century Fire History of Sequoia and Kings Canyon National Parks: A Review and Evaluation of Our Knowledge. AFE Misc. Publ No. 1.

The majority of research has focused on the giant sequoia mixed-conifer forest, and includes a range of topics:

  • Detailed, multi-century fire history from tree rings

  • Fire effects on wildlife, such as birds and insects

  • Tree mortality and regeneration patterns in burned and unburned areas

  • Influence of climate on fire regimes and fire effects

  • Fire effects on surface fuels (woody fuels on forest floor)

Learn more about Giant Sequoias and Fire and about giant sequoia responses to a recent hotter drought - Giant Sequoias and Climate.

Other research has focused on fire in the foothills oak woodlands and chaparral shrublands as well as in higher elevation forests. Collecting data from different types of vegetation from low to high elevations allows scientists to create maps showing areas that historically had the most and least frequent fire occurrence. This information helps fire managers identify areas most in need of prescribed or lightning-ignited fires.

Last updated: October 12, 2023

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