James Mitchell,
Portland State University
Forest Park is an appropriately named 5,200-acre natural area located in northwest Portland, Oregon. A recent study estimated park usage near half a million annual visits and found “trails” to be the park’s most highly valued feature. Unfortunately, many trails were not designed for such traffic as evidenced by slipping hazards, erosion and other ecological impacts. In response to these observations, I partnered with Portland Parks & Recreation to conduct an objective trail impact assessment prescribed by the Forest Park Natural Resource Management Plan (NRMP). I modified methods from past studies to expand on a recently completed trail condition class assessment, which subdivided the Forest Park trail system into four classes of ~250’ trail sections. Linear regression analyses indicated grade and distance to drainage features explained soil loss at much higher levels than seen in past trail impact studies in other natural areas. Since average trail grade proved explanatory of soil loss in linear regression models, I developed and compared average grade variables derived in GIS using new and existing methods. I then used these data to define trail sustainability based on recent recreation ecology literature. The collective methods of my research provide a template for expanding objective trail impact assessments throughout Forest Park, while results and recommendations can help prioritize management action, inform environmental reviews and justify funding for trail system improvements.
