INFLUENCE OF PRESCRIBED BURNING ON UPLAND SOIL PROPERTIES IN MARK TWAIN NATIONAL FOREST, SOUTHEAST MISSOURI OZARKS

Prescribed burning is a forest management practice used to control vegetation growth and improve soil fertility. It is important to understand the effects of forest management on soil health since they can become degraded by over-exploitation and land disturbance. In Mark Twain National forest in southeastern Missouri there is a collaborative effort to restore original shortleaf pine-oak woodlands by using prescribed fire. However, there are questions about the effects of prescribed fire on soil erosion and water quality. This study assesses the influence of prescribed burning on the variability of surface soil properties including litter thickness, bulk density, and organic matter content within the Big Barren Creek watershed. The objectives of the study are to: (1) develop a baseline for soil health indicators including physical properties, organic matter, and nutrients; (2) compare soil characteristics among sites with different fire histories and forest composition; and (3) evaluate if/how prescribed burning effects water quality in local streams. Soil and vegetation assessments were completed at 30 sites generating 330 soil samples across a gradient of burned sites of different ages/frequency and unburned sites from the same soil series. Sampling procedures followed published protocols by the U.S. Forest Service. Preliminary results indicate a decreasing trend in duff layer depth with more frequent/recent burns. There is a positive correlation of tree stem density to duff layer depth. In general, pine stands tend to have 25% greater depths of duff than oak stands. Duff layer depths vary from 10-18 mm in winter months and within site relative standard deviation ranges from 20-30%. Variations of bulk density and loss on ignition due to prescribed burning will be described. This study is one of few to directly evaluate the effects of prescribed burning on soil conditions that relate to landscape stability, watershed hydrology, and water quality effects.