|Thursday, July 08|
The bryophyte friends of ecological restoration in northern climates
* Line Rochefort, Université Laval, Canada
Thirty years of research on the ecology of bryophytes in northern disturbed ecosystems has proven to be useful to improve the success of restoring degraded boreal ecosystems. We argue that the moss layer should be taken into account, not only vascular plants, in ecological restoration. First approaches on the use of bryophytes in ecological restoration, based on what was known on the ecology of mosses in the 1980s, started on the wrong footing. Through numerous experiments and observations at different scales (from petri dish to greenhouses experiments to extensive burnt or degraded ecosystems) several species of bryophytes have emerged as stars of ecological restoration. A superstar in bog restoration is definitively Polytrichum strictum. Fens are more diverse in plant communities; consequently, several stars have been uncovered. Ptychostomum pseudotriquetrum and Marchantia polymorpha are good candidates as pioneer bryophytes to prepare the ground for later successional such as Campylium stellatum and Tomentypnum nitens. Sphagnum warnstorfii should be included in the plant material for reintroduction if a rapid return of the carbon sequestration function is sought. When wetland rewetting is not optimal, Aulacomnium palustre is a good ally for restoring degraded ecosystems. In northern boreal roadside borrow pits, Racomitrium canescens and Sterocaulon paschale are the best species to reintroduce to restart soil formation processes. Data supporting the work of these stars in ecosystem restoration will be presented.
What do lichens tell us about landscapes?
* Yolanda Wiersma, Memorial University, Canada
Patrick Lauriault, Memorial University
Tegan Padgett, Memorial University
Rachel Wigle, Memorial University
Troy McMullin, Canadian Museum of Nature
An essential part of ecological restoration is the ability to assess progress towards a desired state. Ideally, we can use benchmarks of “pristine” conditions to assess the success of restoration actions. In the absence of historical data on a particular site, the presence of indicator species known to be sensitive to anthropogenic disturbances can be a useful tool. Scientists have long known that lichens are good indicators for air quality. Research in my landscape ecology lab has shown that they can also indicate the ecological condition of the wider landscape. In this talk, I will highlight recent research from my lab group that merges expertise in landscape ecology and lichenology. We have used lichens to assess critical habitat for a species-at-risk, and developed strategic sampling techniques to assess nuances in habitat quality. These have included both micro-scale habitat (e.g., tree condition) and site level (stand condition) attributes as well as consideration of air quality and forest continuity. Our work has informed long-term monitoring in a national park, identified critical habitat for a species-at-risk, and helped to assess if lichens can be useful indicators for forested wetland classification.
Rich fens may be prone to retrogressive succession after in situ oil sands exploration disturbance without restoration measures
* Richard Caners, Royal Alberta Museum, Canada
Vic Lieffers, University of Alberta
Varina Crisfield, Université de Sherbrooke
Bryophytes have key roles in the formation of hummock-hollow topography in rich fens, and influence the development of vegetation with different elevation requirements relative to the water table. However, in the preparation of drilling pads for in situ oil sands exploration (OSE) in winter, peatland surfaces are reworked and flattened. When pads are abandoned after drilling, the depressed surface layers and reduced microtopography tends to leave most surface positions flooded after heavy summer rains. In northeastern Alberta, Canada, we examined natural regeneration in rich fens 7 (2012) and 14 years (2019) after OSE with minimal restoration measures. Within each fen for both years, we examined bryophyte diversity and composition at the highest and lowest elevations relative to the water table, as well as tree regeneration and surface topography, on drilling pads and in adjacent reference habitat. In 2019, tamarack seedling densities and bryophyte richness had decreased significantly on drilling pads and adjacent reference habitat compared to 2012. The frequency of most bryophytes was also lower than 2012, including some mosses that are seedbeds for tree establishment. We propose that heavy summer rains during the study caused surface flooding and a significant shift in bryophyte composition between years for sampled habitats. Past research shows that development of artificial hummock topography on OSE drilling pads provides elevated habitat for flood-intolerant plants, including hummock-forming bryophytes. However, in the absence of restoration measures, OSE-disturbed rich fens with a water table near the surface may be susceptible to periodic surface flooding and successional retrogression.
Bryophyte and lichen responses to environmental changes resulting from seismic line disturbance in boreal ecosystems of northwestern Alberta
* Anna Dabros , Natural Resources Canada, Canadian Forest Service, Canada
Kellina Higgins , Natural Resources Canada, Canadian Forest Service
Jaime Pinzon , Natural Resources Canada, Canadian Forest Service
Bryophytes and lichens often provide a growing medium for vascular plants, therefore, knowledge of how they respond to seismic line disturbances may improve understanding of succession, regeneration potential. We assessed environmental conditions and non-vascular species abundance and composition on seismic lines (used for oil and gas exploration), and in the adjacent ecosystem at two sites in Alberta: an upland boreal forest (near Swan Hills) and a boreal peatland (near Peace River). In the uplands, we studied less than a decade old low-impact seismic lines, and in the peatland, ~30-70 year old conventional seismic lines. Soil moisture and light were higher on the lines at both sites. Soil at 2-25m from the line edge was also drier than interior peatland 75m away, indicating edge effects. Soil temperature was higher on the seismic lines at the upland, but not the peatland site. At the upland site, bryophytes and lichens were less abundant on the lines than in the forest when sampled in 2014, but five years later, they have shown a remarkable recovery on the lines. At the peatland site, lichens were less abundant 2-25m from the line edge, compared to 75m away. On the lines, Sphagnum constituted a nearly 100% cover, while other bryophytes and lichens were almost absent. However, Sphagnum and feathermoss were equally and highly abundant in the adjacent peatland. Environmental conditions and vascular and non-vascular species composition did not differ among the lines of different ages in the peatland, indicating arrested succession, and a need for active restoration.
The role of bryophytes in carbon exchange in disturbed and restored peatlands in Canada
* Maria Strack, University of Waterloo, Canada
Resource development across Canada has resulted in a network of disturbances, including peat extraction areas, mines, well-pads, transportation corridors and seismic lines, many of which intersect with peatland ecosystems. While structural and hydrological changes resulting from these disturbances are usually readily apparent, how they affect carbon storage and greenhouse gas exchange remain understudied. Nevertheless, restoration treatments have been designed and are now being applied, with evidence suggesting they can restore carbon sink function in many cases. Bryophytes play a critical role in peatland carbon storage in undisturbed ecosystem, but vascular plants have been shown to dominate carbon uptake in many disturbed and restored sites. Using a series of case studies, the role of bryophytes in carbon and greenhouse gas exchange in disturbed and restored peatlands will be explored.