Reclaiming abandoned trails requires as much attention and planning as constructing a new trail. If you're rerouting a section of trail, the new section needs to be well designed, fun, and better than the one you're closing. If your new trail doesn't provide a better experience than the old trail, visitors will keep using the old one!
The goal is to reduce the impact trails have on the landscape. Simple restoration may consist of blocking shortcuts and allowing the vegetation to recover. Complex restoration projects include obliterating the tread, recontouring, and planting native species. Careful monitoring and followup are needed to ensure that almost all evidence of the old trail is gone. Restoration projects range from simple and relatively inexpensive to complex and costly (figure 89).
For more detailed advice on restoration, see the "Wilderness and Backcountry Site Restoration Guide" (Therrell and others 2006).
Past practices of trail abandonment have left permanent scars on the land. You probably know of abandoned trails that had a few logs and rocks dragged into the tread and trenches. Decades later, those same trails are still visible, still eroding, still ugly, and sometimes, still being used!
Reclamation strategies include: closure, stabilization, recontouring, revegetation, and monitoring. Restoration needs to be carefully planned. The consequences of each strategy should be examined. Consult with a hydrologist, landscape architect, and soil and plant specialists when planning to reclaim an old trail.
Each abandoned trail section should be reclaimed. This is true whether an entire trail is abandoned or a segment with multiple trails is being narrowed to one tread. If the abandoned trail is not blocked to prevent further use, it may persist indefinitely. Closure is particularly important if stabilization and revegetation are to succeed. The abandoned tread should be blocked to all traffic, recontoured, and disguised (figure 90) to prevent users from being tempted to take it. This work should be completed for all segments visible from trails that remain open.
Stabilizing abandoned tread to prevent further erosion will promote natural revegetation in some instances. Trails break natural drainage patterns and collect and concentrate surface waterflows. Restoring the natural contour of the slope reestablishes the local drainage patterns and reduces the likelihood of erosion. Recontouring usually eliminates any temptation to use the old trail and assists revegetation. Pull fillslope material back into the cut and use additional material to rebuild the slope, if necessary.
Completely break up or scarify the compacted tread at least 4 inches deep. Doing so will allow native grasses, plants, and seed to take hold and grow. Fill in the visual or vertical opening of the corridor by planting shrubs, trees, and even deadfall (figure 91). Finally, sprinkle leaves and needles to complete the disguise.
Remove culverts and replace them with ditches.
Check dams are used on sections of abandoned, trenched tread to stop erosion and hold material in place during site restoration. Check dams are intended to slow and hold surface water long enough for the water to deposit sediment it is carrying. Check dams should be used with drainage structures to reduce overall erosion from the abandoned tread (figure 92).
Drawing of the side view and top view of a check dam. The drawing includes the text:
Check dams are best used as holding structures for fill to help recontour the old tread. The material used in the dam should be seated in an excavated footing that extends into the sides of the gully. As material behind the dam builds up, additional levels can be added to the dam with enough batter to keep the dam stable against the pressure of the fill. The top of the dam should be level or slightly higher than the excavated footing. For watertightness, the uphill face of the dam should be chinked and covered with tamped fill. These trenches take a long time to fill up. Most never do. If they do, add fill below the dam to finish the process.
Spacing between dams depends on the steepness of the old grade and the degree of restoration desired. If the check dams are intended only to slow down erosion on a 25-percent grade, relatively wide spacing is sufficient, every 20 meters (65 feet). If the intent is to fill in half of the old trench, the bottom of each dam should be level with the top of the next lower dam. On steeper grades, the dams need to be closer together (figure 93). If the intent is to approach complete recontouring of the trench, the dams should be closer still, especially on grades steeper than 25 percent. A point of diminishing returns is reached on grades steeper than 40 percent. Check dams would have to be built right on top of each other to retain soil at the full depth of the trench.
Revegetation can be accomplished passively or actively. Passive revegetation allows surrounding vegetation to colonize the abandoned trail. This process works when erosion has been stopped, precipitation is adequate, the tread has been scarified, and adjacent vegetation spreads and grows rapidly. Disturbed soil provides an opportunity for invasive plants to take hold. Active revegetation ranges from transplanting propagated native plants to importing genetically appropriate seed. Successful revegetation almost never happens in a single season. Plan carefully for best results.
There are no cookbook answers for returning abandoned trails to their natural condition. Each site should be evaluated for its potential to regrow and heal. On sites that are moist and relatively flat, it may be possible to block off the trail and allow rehabilitation to proceed naturally. Dry, steep sites will take a lot of work.