Off-highway vehicle (OHV) use in natural areas results in changes in the physical, chemical and structural properties of these ecosystems. Wet areas have lower resilience and longer recovery times following OHV disturbance than surrounding upland areas. Within Blue Rapids Provincial Recreation Area (BRPRA), Alberta, Canada, numerous unmanaged OHV trail crossings traverse wet areas and watercourse features. The current condition and use of these crossings have resulted in vegetation loss, erosion, compaction and sedimentation. This project focuses on the revegetation of 15 crossings in BRPRA, including: exploring how vegetation of degraded and edge areas differs from undisturbed areas; and an investigation of four different balsam poplar and willow planting treatments to identify the most effective method for restoring native canopy vegetation. We used four different types of experimental cutting treatments: dormant un-rooted balsam poplar (Populus balsamifera), dormant rooted (greenhouse) balsam poplar, dormant willow (Salix spp.) and direct plant spring balsam poplar; measured initial diameter when planted the cuttings; height growth, and diameter at the end of the growing season; and monitored survival rates for all treated plants. In addition, we conducted vegetation surveys to compare the plant community composition on the enhanced trail, at the edge, and in adjacent undisturbed forest.
Results/Conclusions
Using 50% as a threshold for acceptable survival rate for restoration in riparian areas, propagation by cuttings was deemed effective for the direct plant spring and dormant un-rooted balsam poplar treatments (56.4-62.2%). The main observed factor causing mortality in the enhanced crossings was OHV use, which despite the efforts of Parks staff is still occurring unsanctioned in nine of the experimentally planted crossings. Plant height growth performance was similar for the field treatments and had increased growth for the greenhouse treatment. The vegetation surveys indicated that the trail had lower species diversity and percent cover when compared to the edge and undisturbed plots. Abiotic and non-vascular composition were characterized by a strong presence of mineral soil on the trail; litter and mineral soil on the edge; and litter, wood and moss on undisturbed areas. The findings of our study will help guide management decisions in recovery after recreational disturbance in natural areas and the practical actions will help to restore the degraded areas so that they are on the trajectory of having similar structure and function to the surrounding area.