U.S. Forest Service Final Research Report Research for the Development of Best Management Practices to Minimize Horse Trail Impacts on the Hoosier National Forest Virginia Tech College of Natural Resources, Department of Forestry Research for the Development of Best Management Practices to Minimize Horse Trail Impacts on the Hoosier National Forest by: Michael W. Aust Jeffrey L. Marion Kevin Kyle Virginia Tech, Dept. of Forestry (0324) Blacksburg, VA 24061 March 2005 Abstract This research investigates horse trail impacts to gain an improved understanding of the relationship between various levels of horse use, horse trail management alternatives, and subsequent horse trail degradation. A survey of existing horse trails on the Hoosier National Forest was used to collect data on use-related, environmental and management factors to model horse trail impacts. Results are analyzed to identify which factors are most easily manipulated by managers to effectively avoid and minimize horse trail impacts. A specific focus includes evaluating the relative effect of trail use level, surfacing, grade, and water control on indices of erosion and trafficability such as trail cross sectional area, estimated erosion, muddiness, and incision. Overall, the Hoosier National Forest horse trails could be significantly improved by relocating or closing inherited trails that directly ascend slope or are excessively steep, reducing the distance between water control structures, and by applying gravel to harden trail surfaces and reduce soil erosion. A set of Best Management Practices for trails are included as a product of this work, with recommendations based on this research. ii TABLE OF CONTENTS TABLE OF CONTENTS ............................................................................................................. 1 TABLES......................................................................................................................................... 3 FIGURES....................................................................................................................................... 4 FIGURES....................................................................................................................................... 4 INTRODUCTION......................................................................................................................... 5 OBJECTIVES ............................................................................................................................... 6 LITERATURE REVIEW ............................................................................................................ 7 POTENTIAL IMPACTS OF TRAILS................................................................................................... 7 POTENTIAL IMPACTS OF HORSE TRAILS....................................................................................... 9 POTENTIAL IMPACTS OF ROADS ................................................................................................. 11 FACTORS AFFECTING TRAIL RESOURCE IMPACTS...................................................................... 12 Use-Related Factors .............................................................................................................12 Environmental Factors ......................................................................................................... 12 Vegetation Type................................................................................................................ 13 Topography....................................................................................................................... 13 Soil and Surface Characteristics ....................................................................................... 14 TRAIL MANAGEMENT ................................................................................................................ 15 Trail Construction................................................................................................................. 15 Trail Standards.................................................................................................................. 15 Location ............................................................................................................................ 16 Road Costs ........................................................................................................................ 18 Trail Grade........................................................................................................................ 18 Trail Slope Length ............................................................................................................ 20 Sidehill Trails.................................................................................................................... 20 Stream Crossings .............................................................................................................. 21 Techniques for Wet Soils.................................................................................................. 22 Tread Hardening ............................................................................................................... 23 Geosynthetics.................................................................................................................... 24 Reinforcing/Augmenting Soil Structure ........................................................................... 25 Trail Maintenance................................................................................................................. 25 Tread Shaping ................................................................................................................... 25 Surface Water Control ...................................................................................................... 26 Vegetation Management ................................................................................................... 27 Visitor Management..............................................................................................................28 METHODS .................................................................................................................................. 29 STUDY SITES.............................................................................................................................. 29 TRAIL SELECTION ...................................................................................................................... 29 FIELD PROCEDURES ................................................................................................................... 29 DATA ANALYSIS ........................................................................................................................ 32 - 1 - RESULTS AND DISCUSSION ................................................................................................. 33 TRAIL INVENTORY INDICATORS................................................................................................. 33 TRAIL IMPACT INDICATORS ....................................................................................................... 35 RELATIONAL ANALYSES ............................................................................................................ 36 Drainage Features................................................................................................................ 43 Modeling Trail Degradation................................................................................................. 43 Individual Trail Summaries .................................................................................................. 46 SUMMARY AND MANAGEMENT RECOMMENDATIONS ............................................ 48 REVIEW AND SUMMARY OF FINDINGS ....................................................................................... 48 STUDY RECOMMENDATIONS ...................................................................................................... 52 Trail Planning and Decision Making ................................................................................... 52 Managing Visitor Use........................................................................................................... 53 Evaluate, Relocate, and Reconstruct Trails.......................................................................... 54 Best Management Practices.................................................................................................. 55 LITERATURE CITED .............................................................................................................. 59 APPENDIX 1. TRAIL SURVEY MANUAL........................................................................... 65 INTRODUCTION .......................................................................................................................... 65 MATERIALS................................................................................................................................ 65 POINT SAMPLING PROCEDURES ................................................................................................. 65 PROBLEM ASSESSMENT PROCEDURES........................................................................................ 70 POINT SAMPLING FORM ............................................................................................................. 71 PROBLEM ASSESSMENT FORM ..................................................................................................