Doctor of Philosophy (PhD)


Plant, Environmental Management and Soil Sciences

Document Type



Soil degradation due to improper use of off road vehicle (ORV) is among the major problems in the Kisatchie National Forest (KNF), especially in Catahoula (CRD), Evangeline Unit, Calcasieu (ERD), and Kisatchie Ranger (KRD) districts. The USDA-Forest Service (USFS) maintains designated trails within the forest, but many ORV users create their own trails. To address this issue, a research project was initiated in 2001 to assess the suitability of KNF soils for ORV traffic using Geographical Information System (GIS) software. The objectives were achieved by utilizing soil properties, rainfall events, soil trafficability ratings, Keetch-Byram Drought Index (KBDI), and infiltration parameters. Various GIS techniques, spatial statistics program, and mathematical models were employed. The spatial variability of KNF soils was determined using the choropleth and summarize zones techniques through ArcViewâ3.2. Surface runoff from soils with varying surface textures was estimated using the Green and Ampt Approach program through Lahey FORTRAN 90 version 4.0. Hotspots, or areas that have potential for soil degradation, and coldspots, or areas that are suitable for ORV use, were identified using the kernel density estimation technique through CrimeStatâ2.0. These areas were also reflected in the trafficability maps. The use of a KBDI critical value of 399 was found to be a rapid method of managing the forest with respect to opening or closing existing trails. The research results can be used by the USFS to effectively manage the forest. Most of the soils that occur within the CRD are suitable for ORV use. A portion of ERD should be restricted from ORV use. KRD should be permanently closed for all ORV traffic. Though the suitability analysis was successful, further research is necessary to test the validity of the methods used in the analyses. The recommended critical KBDI value should also be tested especially for the rainy season. Moreover, to validate the model used to estimate runoff, actual infiltration parameters should be used. Inclusion of other parameters in the model, such as saturation time and thickness will help determine the duration to restrict the ORV use of the forest based upon the soil moisture condition.



Document Availability at the Time of Submission

Release the entire work immediately for access worldwide.

Committee Chair

Wayne H. Hudnall