Restoration of Degraded Trail Crossings in Wet and Riparian Areas Using Balsam Poplar Cuttings, Blue Rapids Provincial Recreation Area, Alberta

Protected areas are established and maintained in Alberta, Canada for the conservation and preservation of natural features and to facilitate their use and enjoyment for outdoor recreation and education. The use of off-highway vehicles (OHV) is a popular recreational activity in Alberta’s parks. OHV use can cause immediate negative impacts on natural areas. These impacts include: soil compaction, altered water infiltration dynamics, inhibition of root growth, and direct damage to native plants, which in turn facilitates the establishment of non-native species. Consequently, the plant community structure on the directly impacted trail and in adjacent forest, can be affected. The structure and function of such degraded ecosystems can be restored through active restoration, including stopping continued damage, recontouring of surface area, and revegetation. One way to quickly re-establish trees or shrubs is through the use of hardwood cuttings, which are stems cut from donor plants. Balsam poplar (Populus balsamifera L.) is a common native tree species in Alberta that is well-suited for such an approach.Blue Rapids Provincial Recreation Area (BRPRA), located outside of Drayton Valley, Alberta, Canada, has supported OHV recreational use for several decades on trails that were originally developed for oil and gas activities (e.g., seismic lines), but is also positioned to conserve the area’s natural features. BRPRA has several kilometers of unmanaged OHV trails, which traverse wet and riparian areas of the North Saskatchewan River. Some of these trails have been decommissioned and targeted for active restoration. This study focused on the revegetation of those decommissioned OHV trails with the use of balsam poplar cuttings. To better understand the factors influencing plant establishment on restored trails I investigated: i) the efficacy of three pre-planting treatments for restoration with balsam poplar cuttings; and ii) if the plant community composition differed on enhanced trails, adjacent edges and adjacent forested areas, as well as if there were differences at each position within two years after trail enhancement. We established a revegetation experiment by planting balsam poplar cuttings prepared with three different treatments (rooted, unrooted, and direct plant) on 15 decommissioned OHV trails within BRPRA. For the rooted and unrooted treatments cuttings were collected from live trees at BRPRA during dormancy, whereas for the direct plant treatment cuttings were collected in early summer. Rooted cuttings were initially rooted in the greenhouse and transferred to the field at the end of the first growing season, whereas for the unrooted and direct plant treatments cuttings were planted in the field in early summer. Survival and growth of the planted cuttings was monitored during the year of establishment through the end of the subsequent growing season. We also investigated the plant community and abiotic variables on restored trails, on their adjacent edges and in the adjacent 10 m forested area both during the year the re-vegetation experiment was established and one year later. The rooted treatment showed overall better survival and taller plants, but did not perform better than the other two treatments in height growth difference during the second growing season; the unrooted treatment had the second-best survival and direct plant had the poorest survival. All three treatments were recommended, since each one might be practical to specific needs of different restoration programs. Initial diameter of the cutting had a nearly significant positive influence on survival during the first growing season and height growth in both growing seasons, optimal initial diameters ranged from 4 to 8 mm. Thus, the use of cuttings with initial diameters from 4 to 8 mm and collected during dormancy is recommended for maximum survival and growth. Environmental conditions on the trail also influenced survival and height growth. Enhanced OHV trails and their associated edges had different plant communities when compared to adjacent forested areas. The increased abundance of non-native species and increase in graminoids on trails and edges is of concern. Trails seem to be favouring the establishment of annual vegetation. Therefore, the planting of native woody species might help plant succession on these trails, although, this cannot yet be predicted. Longer-term monitoring of the enhanced OHV trails can help inform their successional trajectories, including evaluating survival and growth patterns of the three restoration planting treatments.

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