What is a Savanna?
The definition of savanna is an often debated topic among land managers. Simply stated, an oak savanna is an ecosystem consisting of two key layers: an overstory of primarily open-grown oak trees with the canopy cover ranging from 10-60 percent, and a groundcover composed of grasses, sedges, and wildflowers. Prairie fires, which frequently entered the savannas, were critical in maintaining this two-tiered structure. With no sizeable, high-quality remnant savannas in Iowa, we are left with spotty historical accounts, degraded remnants, restoration efforts and our imagination to piece together the great complexity of these savanna communities.

Importance of Fire
Oaks were the predominant tree species of Iowa savannas. Bur oak was probably the most common savanna tree due to its ability to tolerate fire and a wide variety of soil and moisture conditions. The bur oak has several adaptations to fire including an extensive root system; thick, corky bark; and rot resistance even when scarred by fire. A thick, woolly cap protects its acorns. Oaks not only tolerate fire, but their flammable leaves promote it. While less tolerant of fire than bur oaks, white oaks were also a major component of oak savannas. Red oaks, swamp-white oaks, black oaks, hickories and walnuts were present on a more limited basis.

Disappearance of Savannas
Within a 100 years of European settlement savannas were completely wiped out across the state. Many savannas were chosen as ideal sites for homesteads and towns. Savannas flat and rich enough to be farmed were cleared and plowed. Areas too poor for row cropping were often grazed, logged or both. 

Prairie is a community of grasses, forbs, shrubs, animals and microorganisms which has been shaped by disturbance such as fire and grazing. Together these components create an interdependent ecosystem. Prairie can be found as far east as Indiana and as far west as the Rocky Mountains. Its northern reaches extend into Canada and can be found as far south as Texas.

Prairie once covered 70-80% of Iowa’s landscape. Today less than one tenth of one percent of that prairie remains. The US Army Corps of Engineers uses management tools such as prescribed fire and mowing to manage these areas. These tools mimic bison grazing and wildfires that maintained the health of native grassland years ago.

Forestry

Forestry at Lake Red Rock is not focused on timber sales or timber production but rather on timber stand improvements. Since the construction of the dam, the natural resource department has planted hundreds of acres of trees in an effort to encourage native forest ecotypes in a variety of sites. These efforts generally took place in old agricultural fields that were no longer in use and in danger of being overtaken by invasive and undesirable species. Forest plantings provide critical habitat for many wildlife species and once trees mature they will supply a large food source. Many of these plantations have now reached an age where a thinning must occur, this thinning may look destructive but is intended to allow for the remaining trees space to grow.