| Popis: |
Resource exploration and extraction in the arctic causes long lasting disturbances as natural recovery is a long and slow process in the north. With three Canadian diamond mines expected to close in the next fifteen years, many hectares of land will require revegetating. Research conducted in the field at Diavik Diamond Mine Inc, Northwest Territories, Canada (Diavik), and in growth chambers at the University of Alberta, focused on propagation and establishment of shrub species and lichen biocrusts with the objective of developing integrated shrub heath tundra communities. To address the lack of previous research, we conducted a number of large scale studies to assess species behaviours under a variety of conditions that can be used to inform current reclamation practices and guide future research directions. Two growth chamber experiments were conducted over 60 days to examine the effects of common and novel rooting techniques on adventitious and lateral root development on cuttings from eight arctic shrub species. The first experiment had six soaking times (0, 1, 3, 5, 10, 20 days), four indole-3-butyric acid (IBA) concentrations (0, 0.1, 0.4, 0.8 %), and three seasons (summer, fall, spring). The second had a control, three IBA concentrations (0.1, 0.4, 0.8 %), three Salix water extracts, or three smoke water extracts, in two seasons (summer, fall). All eight species developed at least primary and secondary roots in at least one season in one experiment, including one previously untested species, Kalmia procumbens. This is an important milestone for using vegetative propagation for shrub species that lack reliable seed sources. Rooting characteristics were highly variable, with maximum rooting percentages between 3 and 94, and maximum number of roots per cutting between 1 and 117, across species, seasons, and experiments. Dormant Salix cuttings should be collected for revegetation due to strong seasonal influences on rooting; only small seasonal effects were observed for the other seven species. Although rooting percentages were generally low, species specific interactions between season and Salix and smoke water extracts were observed. For Salix, common and novel treatments in our study affected primary and secondary root development differently, indicating treatments must be carefully selected to optimize root system architecture for specific site conditions. Field research focused on biocrust establishment on mining by-products (crushed rock, lake sediment, processed kimberlite), inoculant dispersal (dry placement, slurry), with habitat amelioration techniques (erosion control blanket, tundra soil, woody debris), and containment (jute mat) at Diavik. After three field seasons, uninoculated plots had significantly lower species richness and vegetation cover than inoculated plots. Biocrust retention was highest on plots with erosion control blanket, containment, woody debris, and crushed rock; larger scale application of these treatments should be assessed in future. Growth chamber experiments were conducted to assess the effects of substrate (crushed rock, tundra soil), substrate depth (1, 1.5, 2 cm), substrate sterilization, lichen inoculation, and community composition (Flavocetraria cucullata alone, mixed sieved biocrust, unsieved mixed biocrust) and watering frequency (damp, 1 day, 2 day, 3 day, 10 day) on survival of arctic biocrusts collected from Diavik over six weeks. Mixed species had less decline in live lichen between the start and end of the experiment than Flavocetraria cucullata, and substrate interacted with species inoculation to affect species survival over time. We found that a three day watering frequency and a substrate depth of 1 cm had the least decline in live lichen. Sterilization did not affect lichen survival, and no contamination was observed. Our results highlighted the challenges of growing lichens under controlled conditions as only a few treatments increased live lichen. Given the lack of research and limited success to date in restoring tundra vegetation communities, our research assessing novel propagation and establishment techniques for both shrub species and lichen biocrusts is foundational for community focused arctic revegetation. These results can guide future work incorporating different vegetation types, in conjunction with anthroposol development and placement, that meets the current and future needs of different species and communities, and can create new research opportunities assessing community assembly, vegetation succession, and recovery of ecosystem processes in the arctic. |
