Friday, August 6, 2010 - 8:00 AM

OOS 53-1: Beyond the pavement: Scientific methods for quantifying ecological responses to off-highway vehicle use

Douglas S. Ouren1, Raymond D. Watts2, and Alisa W. Coffin2. (1) USGS, Fort Collins Science Center, (2) USGS

Background/Question/Methods The off highway road network makes up approximately 53% (1.6 million miles) of all roads in the United States.  While providing access, this network also fragments the landscape spatially and temporally.  However the vast majority of road related research has targeted paved roads; limited research done on unpaved roads focused on the physical presence of roads in a geographically constrained context, without considering their functional relationship to the broader road network.   Road use metrics including vehicle type, speed, and volume provide vital information.  When effects on wildlife are being investigated simultaneous collections of road use and animal movements are critical.    The objective of this project is to determine which metrics of road usage provide the most insight on elk (cervus elaphus) habitat use. 
This project used vehicle-counters to study motorized use patterns and volume throughout a mountainous road network in western Colorado.  A 15-site monitoring network was operated where over 180,000 vehicle counts represented three years of use.  While several types of vehicle counters were tested, pneumatic counters provided the most robust data sets.  In order to monitor motorized use data on date, time, vehicle speed, direction of travel and vehicle type were collected.
Simultaneously 50 elk were marked with GPS/VHF collars to monitor their habitat use and movements and relationships to motorized use.  The collars attempted locations every four hours with an expected three year life.
Results/Conclusions Vehicle counts were analyzed by time of day, day of week, season, and year to determine significant patterns of use. In compiling and analyzing the data from this work the group learned that daily OHV use peaked within a two to three hour range for all sites, the overall volume of use varied by site on an annual basis, and vehicle “spawning” is an actual phenomenon.  The project also determined that there are at least two distinct patterns of motorized use - one dominated by the majority of use occurring on the weekends and the other one dominated by use in the middle of the week.  With over 35,000 elk locations collected, various relationships to motorized use are being investigated.  Based on this data, it appears that the relationships between vehicle hourly thresholds, elk movements and distances from roads are important in explaining the impacts of road usage and elk.  This project is demonstrating how quantitative evaluations of road use will provide a foundation for assessing the ecological impacts of road use.