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Can Trail Building Save the Planet? The Environmental Impact of Trails

Castle Rock General Plan Update

Book Review: Uncommon Ground: Rethinking the Human Place in Nature

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Celebrate California Trail Days and Earth Day 1999 at Arastradero Preserve


From the Editor

Trail Notes

The Trail Companion

Early Spring 1999

Can Trail Building Save the Planet?

The Environmental Impact of Trails

     by Geoffrey Skinner

As we hack away at a hillside and build rock walls on yet another trail project, are we doing more harm to the environment than good? Is building trails an environmentally-sound activity or are we committing ecodestruction? Are we encouraging stewardship and support for the natural world with our work or are we encouraging overuse (and abuse)? Are we encouraging exotic species of plants to invade new areas? Are we designing and constructing trails which will be maintainable, sustainable and which won't cause erosion? I have been reflecting on the environmental impact of trails as Earth Day 1999 approaches and we are only a year away from the 30th anniversary of Earth Day. The topic has been one of perennial interest among Trail Center volunteers. We have discussed the subject during Crew Leader Training, in Board meetings, over lunch, and while at work in the field. Can we build trails and support the environment at the same time?
      A trail is a very small (or some-times not-so-small) road. Some of the same arguments for keeping an area roadless may apply to trails. On a piece of land which has seen relatively little human influence, any disturbance we cause may have significant impact. graphic of planet EarthDuring trail, construction, we regularly uproot plants and scrape away the organic material covering the soil. A trail may bring in many more people than the casual wanderer, potentially pushing animals out of their habitat and damaging more plants and other natural features. Any human presence will have an effect on an ecosystem, whether intentional or not. We value parks and wildlands in part for the very quality of being apparently untouched by humans, but we change the environment with every action that brings large number of humans into a wildland. From this standpoint, a trail will likely degrade the quality of the ecosystem, even if only in its immediate vicinity. In the extreme case, so many visitors will use a trail that the it will become a road, either by design or happenstance, as hikers in Yosemite, Muir Woods, or other very popular parks can see. The broader the swath cut into a wildland and the greater the number of users, the greater the impact. The flattened newts and gopher snakes on fireroads and other wide trails bear silent witness to this impact.
     By building a trail, we may encourage the spread of invasive exotic plant species, such as bull thistle, because many of the invasive exotics thrive in disturbed ground. The effect is most notable when trails are being built through grasslands - thistles may choke the trail the first spring after construction. Trail Center volunteers have built two long trails in grasslands in the past several years, one in Alum Rock Park in San Jose, and the other in Arastradero Preserve in Palo Alto. In both cases, thistle grew so thick that the trails became impassable without mowing. The seeds may have been in place before we arrived, but our work opened up many square feet of bare soil where the seedlings wouldn't be choked out by other plants.
     Like a road, the trail may also have a visual impact, particularly in open grassland or chaparral. The scar is most visible during construction and for some time afterward, but in slower-growing chaparral, the trail may be highly visible for years after completion. image of forest and path Our own project in Santa Teresa Park, the Stiles Ranch Trail, demonstrates how a trail can create a long-lasting visual impact. We needed to build massive rock walls on switchbacks; the rocks blended in with the hillside soon after we finished, but we overestimated the width we needed to clear through the relatively slow-growing brush and the trail could be seen from miles away. Nearly ten years later, brush has finally grown enough to soften the scar. Perhaps the most serious problem we can cause in building a trail is erosion. Again, like roads, trails capture water and direct its flow. When that effect is combined with berms, clogged drains, debris flows or generally poor design, a trail can send a great deal of sediment down-hill, whether in natural drainages or new gullies. The amount of sediment, even in the worst case, is usually far less than similar erosion from a dirt road, but it can still badly damage stream habitat and smother plants.
     With all of these considerations, it might seem obvious that the best thing we could do is to stop building trails - and perhaps remove the existing ones! In some places that may be true. Over the past several years, the Trail Center has, in fact, largely moved away from the business of constructing new trails and has concentrated on preserving existing ones. We have also recommended against building trails in a number of locations because the environmental costs would be too high. On the other hand, the parks we work in are set aside with public money, for the purpose of serving the public in a variety of ways, including recreation and trails. The people who have paid for the park usually expect to have some amount of access; without access, they may not appreciate the land or see the value in its preservation. In the Trail Center mission statement, we say we will "foster stewardship of public lands" and our main strategy to fulfill that mission has been to encourage people's discovery of the value of our wildlands through trail work and trail use. If we accept that our work will have some negative impact on wild-lands, even as we encourage stewardship, what can we do to minimize that impact? Many of the problems - erosion, destruction of habitat, visual scars - may be inherent to trails, but the degree of dam-age is often the result of poor design or construction. The environmental ethic of causing least harm is one which we aim to bring to all of our trail building.
     Sometimes, a trail can be better for the environment than no trail at all. Under the California Environmental Quality Act (CEQA), a project must be evaluated with several options, including the "no project" option - which is the expected out-come if existing conditions are allowed to continue without change. In the area around Castle Rock in Castle Rock State Park, hikers and climbers have created a network of "volunteer" or "social" trails around the sandstone boulders and outcrops. These informal trails are destroying the thin soil cover by compaction and erosion; the existing trail is badly eroded and many visitors don't identify it as a trail at all. With no change, the great number of visitors could cause much of the soil could wash away, with loss of vegetation, slides, and visual blight. One of the Trail Center's current projects is to create an attractive trail that most visitors will want to use while the surrounding area recovers. We anticipate that our rerouted trail will concentrate use and reduce impact much further than the "no project" option would unless the entire area were closed off and fenced.
     Good design is the key to creating a trail with the least impact. Trail Center standards were developed to construct trails which will last a long time with minimal erosion and damage to the environment. Before we ever dig a single shovelful of dirt, we survey our projects very carefully. We take note of any natural features which we may damage or endanger, including plants and rocks, and strive to stay away from them. We look at soil and potential for erosion, including close examination for evidence of earth movement so that we can avoid causing or reactivating a slide. Our grades rarely exceed 10% and we always pay attention to drainages and water flow. We consider the appropriateness of the trail for the terrain and recommend against a route, or even the entire project, if the costs appear to outweigh the benefits. During brushing, we cut carefully, erring on the side of too little, rather than too much; we cut brush up and haul it away instead of piling it on the side of the trail. During construction, we give trail surfaces an outslope that will send water sheeting down a hillside rather than concentrating it, and install drain-age structures such as drain dips and French (rock) drains to carry away excess water. Our reliance on hand tools gives us the ability to shape a trail and minimize scarring in a way that is difficult to achieve with a trail machine. We aim to cut only as much soil as necessary and avoid dumping the excess material over a wide area below the trail. When we finish, we use native materials to cover disturbed ground and speed the healing process. Regular maintenance and monitoring can be a key to minimizing impact. Many erosion problems start small, but if not corrected, can destroy a trail and result in sediment washing into streams. If the soil is fragile, winter closure to some or all users may mean the difference between minor winter damage and a major problem.
     The Trail Center's process of trail design and construction is not perfect - we do make mistakes, but they are nearly all the result of inexperience with a new situation and we learn as much as we can from each problem. Through our experience building trails in grass- lands, we have learned that we can encourage thistle to invade, and that soil exposed to the rains will tend to erode more quickly than trail under tree cover. We pay more attention to soil types since we saw the clay soils on the Stiles Ranch Trail become gullied after winter rains. Every project presents new challenges and variables; we aim to intelligently apply the knowledge we have gained to create the best trails possible in each situation. As I have watched volunteers come to appreciate the land through trail work and have long enjoyed hiking, biking, riding and running on wild-land trails, myself, I, have come to believe that, in the right place and built in the right way, trails can make a positive environmental impact that outweighs their costs. My own support of the environment is the result of time spent on the trail. The more intimately I come to know a wildland, whether by getting my hands dirty in building trail, or as a visitor using a trail to see flowers, trees and birds, the more I value all our wild places. To quote our brochure: "The wealth of public land and open space in the Bay Area is a treasure to value and protect. You can join the hundreds of volunteers who give back to the land through the Trail Center's programs: trail building, restoration, mapping, and other hands-on projects. Help build awareness and support for trails and open space."

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