By Kevin Robertson, PhD and Cinnamon Dixon, Fire Ecology Lab, originally published in the Summer 2022 edition of Quail Call.
The term “ecosystem services” has gotten a lot of buzz in recent years. They are basically products or processes provided by natural lands that benefit humans. It follows that hunting itself is an ecosystem service. However, management for northern bobwhite, especially the use of frequent prescribed fire, can provide many more benefits than just good hunting, which is important for us and our community to appreciate. The Tall Timbers Fire Ecology Program recently published a paper measuring various ecosystem services provided by different land uses in the Red Hills Region.
Given that much of the region is covered with old-field pinelands managed for northern bobwhite, we were particularly interested in how time since abandonment of agriculture followed by application of frequent prescribed fire would influence various ecosystem services. We chose locations with different times since fields were abandoned and burning started using old aerial photographs and maps, categorizing locations into age groups ranging from 5-10 years up to 75-100 years post-agriculture, and then measured many aspects of the plants, soil, and soil fungi and bacteria. We were also interested in how these old-field pinelands compared to native longleaf pine-wiregrass communities as well as current row-crop agriculture, pine plantations, and unmanaged (long unburned) pine-hardwood forests.
The study was replicated in four different areas — in and around Tall Timbers, Livingston Place, Pebble Hill Plantation, and Avalon Plantation — thanks to the hospitality of these and many other private landowners. Our results showed that with increasing time since agriculture there is an increase in perennial grass cover, native plant biodiversity, soil carbon, total ecosystem carbon, and mycorrhizal soil fungi, and a decrease in soil plant pathogens, water runoff, and soil erosion. Soil mineral nutrients including phosphorus, calcium, magnesium, and potassium also decreased toward levels closer to native pine communities, which is helpful for minimizing off-site and weedy plants and decreasing pollution from runoff. Frequently burned old-field and native pinelands also fared well compared to other common land uses.
Naturally, row-crop agriculture produces the most food and fodder, pasture produces the most forage, and pine plantations produce the most timber. However, frequently burned pinelands showed lower losses of water to transpiration, higher water infiltration, and higher bee pollinator diversity than pine plantations and unmanaged forests. They also had higher total ecosystem carbon and less runoff and sedimentation than pastures and row crops. Older old-fields and native pinelands had the overall highest native plant diversity which translates to diversity of insects and the vertebrate animals that depend on them.
They also had the healthiest soil in terms of C:N ratio, lowest bulk density, most natural levels of mineral nutrients and nitrogen, and symbiotic fungi that help plants grow. These results highlight the many benefits provided by quail management, especially use of frequent prescribed fire and timber management to maintain an open canopy, on mostly post-agricultural landscapes like the Red Hills. However, it also follows that many of the benefits accumulated over time are lost by intensive soil disturbance that more or less returns the soil and vegetation to agricultural conditions and resets the successional clock.
Given that native pine savannas generally had the highest levels of most ecosystem services, prioritizing them for protection from intensive soil disturbance is a good idea. In summary, frequent fire on oldfield and native pinelands provides a wide range of services helpful to both landowners and the broader community, although some diversity of land use is necessary for providing all the benefits we humans need to thrive.