Remote Sensing of Fire Effects
By Kevin Robertson and Joshua Picotte
This summer will mark the end of the Fire Ecology Program's three-year study supported by the Joint Fire Sciences Program to develop satellite remote sensing methods to measure fire effects and size of burned area in southeastern habitats. The work was led by Joshua Picotte and focused on the Apalachicola National Forest, Osceola National Forest, and the Okefenokee National Wildlife Refuge.
Our method was to first go to areas recently burned by prescribed fires or wildfires and measure fire effects on plants and soil on the ground in 731 plots on the three different public lands. These plot locations were then overlain with satellite reflectance data to match reflectance values with fire effects. We also mapped the perimeters of burns on the ground to test the accuracy of the remote sensing for measuring burned area, which could potentially be used for fire monitoring at the state or regional level. We compared results among seasons of burn as well as among sandhill, flatwoods, and depression swamp habitat types.
The method was about 75% accurate in correctly identifying levels of fire effects, although the accuracy depended on habitat type. The method was most accurate for simply measuring burned area, where the average bias was under 1%. An important finding of the research was that in southern habitats, where vegetation re-growth is very rapid following fire, the satellite flyover has to be within about eight weeks following the fire, although muck fires in swamps can be detected much later. This time frame can be restrictive because of cloud cover on reflectance images, although clear images can usually be found during the spring when most prescribed burning take place. If correctly applied, this method could be used to estimate fire effects and burned acreage in southeastern habitats on a large scale, which is a critical need for monitoring habitat quality, accurately estimating pollution from fires, and assessing wildfire danger. Training on how to use this method in the Southeast was offered through two workshops and another one is planned, reaching over 50 professionals who can put this technology to good use.
Burned area and burn severity of 2008 burns on Tall Timbers as detected by the remote sensing method.