INFLUENCE OF LLAMAS, HORSES, AND HIKERS ON SOIL-EROSION FROM ESTABLISHED RECREATION TRAILS IN WESTERN MONTANA, USA

Various types of recreational traffic impact hiking trails uniquely an d cause different levels of trail degradation; however, trail head res trictions are applied similarly across all types of packstock. The pur pose of this study was to assess the relative physical impact of hiker s, llamas, and horses on recreational trails. Horse, llama, and hike, traffic were applied to 56 separate plots on an existing trail at Lubr echt Experimental Forest in western Montana. The traffic was applied t o plots at intensities of 250 and 1000 passes along with a no-traffic control under both prewetted and dry trail conditions. Soil erosion po tential was assessed by sediment yield and runoff (using a Meeuwig typ e rainfall simulator), changes in soil bulk density, and changes in so il surface roughness. Soil moisture, slope, and rainfall intensity wer e recorded as independent variables in order to evaluate the extent th at they were held constant by the experimental design. Horse traffic c onsistently made more sediment available for erosion from trails than llama, hiker, or no traffic when analyzed across wet and dry trail plo ts and high and low intensity traffic plots. Although total runoff was not significantly affected by trail user, wet trail traffic caused si gnificantly greater runoff than dry trail traffic. Llama traffic cause d a significant increase in sediment yield compared to the control, bu t caused erosion yields not significantly different than hiker traffic . Trail traffic did not increase soil compaction on wet trails. Traffi c applied to dry trail plots generally resulted in a significant decre ase in soil bulk density compared to the control. Decreased soil bulk density was negatively correlated with increased sediment yield and ap peared to result in increased trail roughness for horse traffic compar ed to hiker or llama traffic. Differences described here between llama and horse traffic indicate that trail managers may want to consider m anaging packstock llamas independent of horses.