Scrub communities in Florida are well adapted to fire and other natural disturbances. Historically, in an undisturbed environment, frequent lightning ignitions maintained natural scrub in a low, open stature. European settlement brought open range management for ranching and scrub clearing for citrus groves. Fires were used annually to encourage herbaceous growth and improve range for cattle. Open range management continued in Brevard County until 1925 and in Volusia County until 1947 when cattle had to be fenced in and fires were restricted to ranchers’ property. Fire was viewed as a threat to timber resources, which led timber industries to propose wildland fire suppression in the early 1940’s. Organized wildland fire suppression in Brevard County began in the 1950’s.

NASA began acquiring land in early 1962 on north Merritt Island, along the east coast of Central Florida. KSC is now the largest undeveloped land holding on the east coast of Florida. After NASA acquired the land, fire suppression remained in effect on KSC until 1981, when catastrophic wildfires became a safety and operations problem. The first fire management plan was developed in 1981 to reduce dangerous fuel levels and prevent future fuel buildup on KSC. The realization that scrub communities were becoming degraded and concern for wildlife species led to fire being used as a tool for restoring and maintaining scrub on KSC.

Restoring fire to the pyrogenic communities of KSC is very important for maintenance of natural biophysical processes and overall health of the region. To understand the effects of anthropogenic change on spatial fire behavior, we modeled historic and current fire spread across KSC. During the modeling, we held all variables constant with the exception of fuels, which represented different time periods. This approach isolated the differences between natural and anthropogenic fuel conditions, providing valuable perspective on baseline burning conditions for land managers.

The results show that anthropogenic influences have affected scrub and flatwoods fuel continuities and flammability, causing a reduction in fire extent (see the figure). The simulations show that in 1920 fires would burn until the fuels were exhausted or meteorologic conditions became unfavorable. In 1943, fires began to be confined by anthropogenic features on the landscape and were even more restricted by these features in 1990. Fragmentation, however, is not the only anthropogenic obstacle for fire. Past fire suppression policies altered land cover and, hence, fuels in several ways. The absence of fire in this fire-maintained ecosystem has allowed scrub to grow to unnatural heights, excluding fire in all but the most extreme meteorologic conditions. Exotic and hardwood species invasion of swale marshes has increased with fire suppression policies, reducing flammability across the KSC landscape.

The results presented here help to quantify anthropogenic effects on fire behavior. The fires simulated on the relatively natural 1920 landscape burned freely until fuels or meteorologic condition became unfavorable. The 1943 and 1990 simulations show that fires have become much less governed by natural variables, such as fuels and meteorological conditions, but rather by human-imposed barriers, even in the absence of active fire suppression.

Key accomplishments:

• 1997: Developed study to investigate spatial historic land cover trends on KSC.
• 1998: Developed and applied method for mapping 1943 land cover for Indian River Lagoon watershed.
• 1999: Developed and applied method to model 1920 land cover pattern for Indian River Lagoon watershed.
• 2001: Developed historic fuel models for KSC.

Key milestones:

• 1999: Published study investigating historic land management and land cover trends.
• 2000: Published paper on modeling spatial reference conditions for southeast landscapes.
• 2001: Developed modeling framework for quantifying historic fire patterns.

Contact: Dr. W.M. Knott (William.Knott-1@ksc.nasa.gov), YA-D3, (321) 867-6988
Participating Organization: Dynamac Corporation (B.W. Duncan)