THE FLORIDA CATTLEMAN AND LIVESTOCK JOURNAL
Grasslands: The Importance of Mosaics for Wildlife
For questions or comments regarding this publication contact: Dr. Raoul Boughton, University of Florida, IFAS
Natural grasslands in the US have been disappearing as land uses and management of our landscapes alter. Urban sprawl and agricultural intensification have reduced many grasslands; changes in fire and flooding regimes and loss of grazing by large herbivores has allowed establishment of woody shrubs and a shift to more wooded and forested habitats. These woody habitats were always part of the mosaic, often found in gullies, in fire shadows, and areas that just didn’t carry fire, but the woods in many places did not dominate the landscape. Nor were vegetation communities fixed, they were melded by disturbance, and disturbances were not always the same. Fire is a disturbance, and grasslands one year after fire are quite different to grasslands five years after fire, in both species diversity and structure. For a diverse community it is important to have a mosaic of times since fire, short and long, as different species have adapted to different fire disturbances to survive.
Fire was not the only regular environmental disturbance in Florida. The summer wet season created a hydroperiod where a rise in the water table produced extended summer flooding in many areas of the peninsular. This hyrdoperiod of flooded plains maintained both wetlands and wet prairie grasslands, inhibiting the ability of woody shrub and tree establishment, as did fire. Through engineered drainage we have modified the hydroperiod to be shorter creating less flooding, but in doing so have likely reduced and changed native grassland habitats. Coupled with less frequent burning the disturbances once common in maintaining grasslands have been considerably altered.
As land was parceled, broken up, sold, and managed in smaller and smaller areas, wide ranging fires were diminished and many grasslands were set on a different trajectory, and with those changes many species of wildlife were also impacted. In addition grassland habitats have been further modified to “improved” states for grazing, using drainage, fertilization, pH adjustments and planting of higher quality non-native forage grasses, such as Bahaia grass, Pangola grass and Limpograss. These high productivity improved grasslands are more homogenous than the natural systems, but still provide habitat for many grassland species of wildlife. In some cases they are even preferred. For example, species such as Eastern Meadowlarks, Burrowing Owl and Crested Caracara use improved pastures and possible increase reproductive success in improved pasture. It has been shown that Crested Caracara have smaller territories on improved pastures, Burrowing Owls often select grazed improved pasture for burrow locations, and Eastern Meadowlarks nest in these improved systems.
To have a diversity of wildlife it is important to maintain a mosaic or patchwork of habitats and a sea of homogenous grass is not optimal. Using birds again as an example, you will find different species that need native grasslands. Bachman’s Sparrow is a species found in grassy open flatwoods and occurs more frequently if areas are maintained by burning and is not found in improved pasture. Similarly, the Endangered Florida Grasshopper Sparrow, a now almost extinct species of native grasslands also prefers to use areas burnt one to two years previously. A favorite game species of the south, the Bob White Quail require diverse grassland and shrubs, as they are attracted to newly burnt areas to feed on seeding forbs but also require denser grasses and shrubs for nesting and escape from predators.
The take home message for improved wildlife diversity is creating a mosaic of different vegetation communities. Improved pasture can be one tile of the mosaic, but for diversity native grasslands are also important. One important tool we can use is fire and an appropriate burn program is essential to ensure a diversity of length of time since last burn. Protecting remaining native grasslands from conversion to improved pasture is important for the conservation of certain species. Coupled with appropriate burn programs native grasslands can be managed well for both wildlife and grazing. Assistance programs are available through USDA NRCS Agricultural Conservation Easement Program and to learn more I would encourage you to visit your local NRCS agent, read about the programs on http://www.nrcs.usda.gov, or just give me a call at the Range Cattle Research and Education Center: 863-735-1314 ext. 216.
You are invited to join me by webinar on May 20, at noon, when I will present the information covered in this Ona Report. Afterwards, I will be available to answer questions. To participate in this webinar you simply need to register online: https://attendee.gotowebinar.com/register/351230890482 or visit our website: https://rcrec-ona.ifas., a link will be available there. There is no cost to attend.