Assessing the Environmental Impacts, Condition and Sustainability of Mountain Biking Trails in an Urban National Park.

Mountain biking is a popular recreational activity in natural areas, with thousands of formal trails designed, constructed and maintained by land managers. Increasingly, there are also rising numbers of informal trails created by riders. A challenge for land managers is identifying, assessing, and then mitigating environmental impacts created by trails, including in protected areas. Here we assessed mountain biking trails in a large, popular national park on the Gold Coast, Australia, addressing the currently limited research comparing the extent, environmental impacts, condition and sustainability of these trails. Impacts from the 31.4 km of formal and 33.7 km of informal trails through the forests in Nerang National Park (1659 ha) included soil erosion (16.48 m3) and loss of vegetation along and adjacent to the trails (90,955 m2). Formal trails were six times more popular and wider on average (1.1 m vs 0.7 m) than informal trails, but less incised than informal trails (4.6 cm deep vs 6.3 cm). Generalised Linear Models showed that Trail Grade, slope and alignment best-predicted trail condition, highlighting the importance of good trail design in minimising trail impacts. It is recommended most of the informal trails are closed and rehabilitated, as they were not well-designed, increase fragmentation and have environmental impacts, with some traversing ecologically sensitive areas. In addition, some formal trails need to be upgraded to deal with erosion and other impacts. More broadly, the increasing demand for mountain biking must be addressed, including exploring opportunities to promote areas outside of national parks while minimising environmental impacts and other challenges associated with the creation and use of informal mountain bike trails in protected areas.

Trail sustainability: A state-of-knowledge review of trail impacts, influential factors, sustainability ratings, and planning and management guidance.

Protected areas (PAs) provide many important recreational, social, and economic benefits that are largely dependent on their ability to sustain visitation. Trail networks are a critical tourism infrastructure element that directly accommodate high quality recreation activities and experiences while providing access to and protection of irreplaceable natural and cultural resources. Unfortunately, most trail networks consist of historic "legacy" trails that were not sustainably designed and whose intensive use cause unacceptable impacts to PA resources, experiences, and values. This paper provides an international state-of-knowledge review of trail science research within the field of recreation ecology to describe common trail impacts and factors that influence trail degradation that trail stewards can manipulate to enhance the sustainability of trail networks. Two emerging models that seek to rate trail topographic sustainability are presented to illustrate their potential utility to PA managers. Expanding and incorporating trail science research into the sustainable trail planning, design, and Best Management Practice literature are also discussed.

Comparison of trailside degradation across a gradient of trail use in the Sonoran Desert.

As recreational visitation to the Sonoran Desert increases, the concern of scientists, managers and advocates who manage its natural resources deepens. Although many studies have been conducted on trampling of undisturbed vegetation and the effects of trails on adjacent plant and soil communities, little such research has been conducted in the arid southwest. We sampled nine 450-m trail segments with different visitation levels in Scottsdale's McDowell Sonoran Preserve over three years to understand the effects of visitation on soil erosion, trailside soil crusts and plant communities. Soil crust was reduced by 27-34% near medium and high use trails (an estimated peak rate of 13-70 visitors per hour) compared with control plots, but there was less than 1% reduction near low use trails (peak rate of two to four visitors per hour). We did not detect soil erosion in the center 80% of the trampled area of any of the trails. The number of perennial plant species dropped by less than one plant species on average, but perennial plant cover decreased by 7.5% in trailside plots compared with control plots 6 m off-trail. At the current levels of visitation, the primary management focus should be keeping people on the originally constructed trail tread surface to reduce impact to adjacent soil crusts.

Differences in the impacts of formal and informal recreational trails on urban forest loss and tree structure.

Recreational trails are one of the most common types of infrastructure used for nature-based activities such as hiking and mountain biking worldwide. Depending on their design, location, construction, maintenance and use, these trails differ in their environmental impacts. There are few studies, however, comparing the impacts of different trail types including between formal management-created trails and informal visitor-created trails. Although both types of trails can be found in remote natural areas, dense networks of them often occur in forests close to cities where they experience intense visitor use. To assess the relative impacts of different recreational trails in urban forests, we compared the condition of the trail surface, loss of forest strata and changes in tree structure caused by seven types of trails (total network 46.1 km) traversing 17 remnants of an endangered urban forest in Australia. After mapping and classifying all trails, we assessed their impact on the forest condition at 125 sites (15 sites per trail type, plus 15 control sites within undisturbed forest). On the trail sites, the condition of the trail surface, distance from the trail edge to four forest strata (litter, understory, midstorey and tree cover) and structure of the tree-line were assessed. Informal trails generally had poorer surface conditions and were poorly-designed and located. Per site, formal and informal trails resulted in similar loss of forest strata, with wider trails resulting in greater loss of forest. Because there were more informal trails, however, they accounted for the greatest cumulative forest loss. Structural impacts varied, with the widest informal trails and all formal hardened trails resulting in similar reductions in canopy cover and tree density but an increase in saplings. These structural impacts are likely a function of the unregulated and intense use of large informal trails, and disturbance from the construction and maintenance of formal trails. The results demonstrate that different types of recreational trails vary in the type and range of impacts they cause to forests. They highlight the importance of careful consideration towards management options when dealing with trail networks especially in areas of high conservation value.