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  • OPEN ACCESS
    Opportunities and trade-offs for expanding agriculture in Canada’s North: an ecosystem service perspective
    FACETS • Vol. 6 • pp. 1728 - 1752
    Climate change will create warmer temperatures, greater precipitation, and longer growing seasons in northern latitudes making agriculture increasingly possible in boreal regions. To assess the potential of any such expansion, this paper provides a first-order approximation of how much land could become suitable for four staple crops (corn, potato, soy, and wheat) in Canada by 2080. In addition, we estimate how the environmental trade-offs of northern agricultural expansion will impact critical ecosystem services. Primarily, we evaluate how the regulatory ecosystem services of carbon storage and sequestration and the habitat services supporting biodiversity would be traded for the provisioning services of food production. Here we show that under climate change projected by Canadian Earth System Model (CanESM2) Representative Concentration Pathway 4.5, ∼1.85 million km2 of land may become suitable for farming in Canada’s North, which, if utilized, would lead to the release of ∼15 gigatonnes of carbon if all forests and wetlands are cleared and plowed. These land-use changes would also have profound implications for Indigenous sovereignty and the governance of protected and conserved areas in Canada. These results highlight that research is urgently needed so that stakeholders can become aware of the scope of potential economic opportunities, cultural issues, and environmental trade-offs required for agricultural sustainability in Canada.
  • OPEN ACCESS
    Safety Net Ontario: Ontario’s outsized role in the “Global Safety Net” for climate and biodiversity
    FACETS • Vol. 8 • pp. 1 - 17
    Dinerstein et al. present a spatially explicit global framework for protected areas needed to reverse catastrophic biodiversity losses and stabilize climate. The Province of Ontario (Canada) stands out in this “Global Safety Net (GSN)” as a critical jurisdiction for meeting those goals, because of both the large extent of roadless lands and high carbon storage in terrestrial ecosystems. Simultaneously, pressure is increasing to develop unmanaged lands in Ontario, particularly in the Far North, for resource extraction. Here, we extract data from the GSN to identify and calculate the areal extent of target regions present in Ontario and critically review the results in terms of accuracy and implications for conservation. We show that when region-specific data are incorporated, Ontario is even more significant than what is shown in the GSN, especially in terms of carbon stocks in forested and open peatlands. Additionally, the biodiversity metrics used in the GSN only partially capture opportunities for conservation in Ontario, and the officially recognized extent of Indigenous lands vastly underestimates the role of First Nations in conservation. Despite these limitations, our analyses indicate that Ontario plays an outsized role in terms of its potential to impact the trajectories both of biodiversity and climate globally.
  • OPEN ACCESS
    Using Holocene paleo-fire records to estimate carbon stock vulnerabilities in Hudson Bay Lowlands peatlands
    FACETS • Vol. 8 • pp. 1 - 26
    Holocene fire records from charcoal are critical to understand linkages between regional climate and fire regime and to create effective fire management plans. The Hudson Bay Lowlands (HBL) of Canada is one of the largest continuous peatland complexes in the world and is predicted to be increasingly impacted by wildfire. We present three charcoal records from a bog in the western HBL and demonstrate that median fire frequency was higher in the Middle Holocene, related to warmer regional temperatures and higher evaporative demand. Holocene fire frequencies are lower than in western Canadian peatlands, supporting that the HBL lies in the transition between continental and humid boreal fire regimes. Apparent carbon accumulation rates at the site were not significantly different between the Middle and Late Holocene, suggesting that higher fire frequency and enhanced decomposition offset the potential for higher rates of biomass production. We compile records from the boreal region and demonstrate that increasing fire frequency is significantly correlated with diminishing long-term carbon accumulation rates, despite large variation in response of peatlands to fire frequency changes. Therefore, the paleo-record supports that higher fire frequencies will likely weaken the capacity of some northern peatlands to be net carbon sinks in the future.
  • OPEN ACCESS
    Snow, ponds, trees, and frogs: how environmental processes mediate climate change impacts on four subarctic terrestrial and freshwater ecosystems
    FACETS • Vol. 8 • pp. 1 - 15
    Amplified warming in subarctic regions is having measurable impacts on terrestrial and freshwater ecosystem processes. At the boundary of the discontinuous and continuous permafrost zones, and at the northern extent of the boreal forest, the Hudson Bay Lowlands has experienced, and is projected to continue to experience dramatic rates of climate change in the coming decades. In this review, we explore the impacts of climate change on terrestrial and freshwater ecosystems in the Hudson Bay Lowlands and other environmental processes that mediate these impacts. We surveyed published literature from the region to identify climate indicators associated with impacts on snowpacks, ponds, vegetation, and wood frogs. These climate indicators were calculated using statistically downscaled climate projections, and the potential impacts on ecosystem processes are discussed. While there is a strong trend towards longer and warmer summers, associated changes in the vegetation community mean that snowpacks are not necessarily decreasing, which is important for freshwater ponds dependent on snowmelt recharge. A clear throughline is that the impacts on these ecosystem processes are complex, interconnected, and nonlinear. This review provides a framework for understanding the ways in which climate change has and will affect subarctic regions.
  • OPEN ACCESS
    Wet–dry cycles influence methylmercury concentrations in water in seasonal prairie wetland ponds
    FACETS • Vol. 8 • pp. 1 - 14
    Methylmercury concentrations [MeHg] in whole water were measured in 28 prairie wetland ponds in central Saskatchewan between 2006 and 2012. Ponds fell into four land use categories (established grass, recent grass, traditional cultivated, and certified organic cultivated) and two water level patterns (“Mainly Wet” ponds stayed wet at least until October and “Mainly Dry” ponds dried up each summer). Despite similar atmospheric Hg deposition, average [MeHg] and proportion of total Hg that was MeHg (%MeHg) were higher in water from ponds surrounded with established grass or organic farming; this trend may be driven by high [MeHg] at one Organic site. A stronger relationship was observed with water level patterns. Average [MeHg] and %MeHg were significantly higher in Mainly Wet ponds compared to Mainly Dry ponds. Higher [MeHg] in Mainly Wet ponds were correlated with much higher dissolved organic carbon (DOC) and sulfate (SO4−2) concentrations and higher specific UV absorbance of DOC. We suggest that prairie wetland ponds may not fit the accepted paradigm that wetlands with high [SO4−2] show inhibition of Hg methylation. Our work suggests controls such as the chemical nature of DOC or redox fluctuations in hydrologically dynamic systems may be important in determining net [MeHg] in these sites.
  • OPEN ACCESS
    Assessment of soil organic carbon stocks in Alberta using 2-scale sampling and 3D predictive soil mapping
    FACETS • Vol. 8 • pp. 1 - 17
    A three-dimensional predictive soil mapping approach for predicting soil organic carbon (SOC) stocks (t/ha) at high spatial resolution (30 m) for Alberta for 2020–2021 is described. A remote sensing data stack was first prepared covering Alberta’s agricultural lands. A total of 404 sampling locations were distributed across Alberta using 2-scale sampling: (1) 22 pilot farms representing main climatic zones and (2) conditioned Latin hypercube sampling at each farm. Soil samples were taken at four standard depths (0–15, 15–30, 30–60, 60–100 cm) using soil probes and analyzed for SOC. Predictive models for SOC content and bulk density were built separately and then used to predict at 0, 15, 30, 60, and 100 cm and calculate aggregated SOC stocks per pixel. The SOC content and bulk density models had R squares of 0.61 and 0.68, respectively. Based on these mapping results, grassland soils were consistently associated with higher SOC stocks across all soil types as compared to croplands. The average SOC stock increase for grassland soils compared to cropland soils was 2.1 Mg per hectare, ranging from 2.17 to 6.09 Mg per hectare depending on soil type. Results also showed that >15 % of total SOC stocks were located in subsoil, which was higher than expected.
  • OPEN ACCESS
    A temporal record of microplastic accumulation in sediment cores of the Great Lakes, North America, reflects macroeconomic and regional influences
    FACETS • Vol. 9 • pp. 1 - 10
    Documented plastic pollution throughout the Laurentian Great Lakes system prompted investigation of microplastics (MPs) in sediment cores. We examined offshore sediment cores from Lake Huron (LH43) and Lake Ontario (403A) to understand temporal trends and changes in microplastic (MP) pollution in the size range 53 µm to 2 mm. MP abundances varied from 18.1 to 280.1 particles per g of dry weight sediment (N g−1 dw) in LH43, and 8.2–488.4 g−1 dw in core 403A. The 15 cm cores are equivalent to 56 years of accumulation in Lake Huron and 72 years of accumulation in Lake Ontario. Analysis of the two cores shows an increasing trend in MP accumulation from 1964 to 1989, which mirrors the global plastic production rate. Subsequent peaks and troughs in the MP abundance profiles reflect macroeconomic changes and regional controls. These results show how changing abundances of MPs in lake sediment cores can act as proxies for global perturbations in oil supply as well as national economic shifts.
  • OPEN ACCESS
    Historical gold mining increased metal(loid) concentrations in lake sediments from Nova Scotia, Canada
    FACETS • Vol. 9 • pp. 1 - 14
    Historical gold mining operations between the 1860s and 1940s have left substantial quantities of arsenic- and mercury-rich tailings near abandoned mines in remote and urban areas of Nova Scotia, Canada. Large amounts of materials from the tailings have entered the surface waters of downstream aquatic ecosystems at concentrations that present a risk to benthos. We used paleolimnological approaches to examine long-term trends in sedimentary metal(loid) concentrations, assess potential sediment toxicity, and determine if geochemical recovery has occurred at four lakes located downstream of three productive gold-mining districts. During the historical mining era, sedimentary total arsenic and mercury concentrations and enrichment factors increased substantially at all downstream lakes that received inputs from tailings. Similarly, chromium, lead, and zinc concentrations increased in the sediments after mining activities began and the urbanization that followed. The calculated probable effects of concentration quotients (PEC-Qs) for sediments exceeded the probable biological effects threshold (PEC-Q > 2) during the mining era. Although sedimentary metal(loid) concentrations have decreased for most elements in recent sediments, relatively higher PEC-Q and continued exceedance of Canadian Interim Sediment Quality Guidelines suggest that complete geochemical recovery has not occurred. It is likely that surface runoff from tailing fields, urbanization, and climate-mediated changes are impacting geochemical recovery trajectories.
  • OPEN ACCESS
    Seasonal patterns and key chemical predictors of dissolved greenhouse gases in small prairie pothole ponds
    FACETS • Vol. 9 • pp. 1 - 18
    Shallow ponds can provide ideal conditions for production of greenhouse gases (GHGs) carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O), and thus are important to include in global and regional GHG budgets. The Canadian Prairie Pothole Region contains millions of shallow natural ponds, and we investigated GHG dynamics in 145 ponds across the region. Ponds were consistently supersaturated with CH4, often supersaturated with CO2 (57% occurrence), and often undersaturated with N2O (65% occurrence). Spring measurements showed higher N2O saturation (p = 0.0037) than summer, while summer had higher CH4 (p < 0.001) and CO2 (p = 0.023) saturation than spring. Ponds exhibited large physicochemical variation, yet sulfate concentration and pH were strong predictors of dissolved CH4 and CO2, respectively. No predictor was identified for N2O. The link between sulfate and CH4 has important implications as dissolved CH4 in low sulfate (<178 mg L−1) systems was much more responsive to changes in temperature. This research fills an important knowledge gap about the GHG dynamics of prairie pothole ponds and the role of water chemistry for diffuse GHG release. Our work can also be used in ongoing efforts to describe ecosystem services (or disservices) assigned to ponds in this agriculture-dominated region.
  • OPEN ACCESS
    A pilot bioavailable strontium isotope baseline map of Southern British Columbia, Canada
    FACETS • Vol. 9 • pp. 1 - 11
    Strontium isotopes are used for provenience and mobility studies in archaeology, ecology, and forensic studies, and rely on accurate baseline maps that are used to compare and interpret human and animal strontium ratios. Here, we present a bioavailable 87Sr/86Sr map, also called an isoscape, for southern British Columbia derived from modern plant samples’ 87Sr/86Sr ratios. We sampled 67 medium root depth plants over a 900 km transect from the southern BC coast to inland BC to capture the natural 87Sr/86Sr ratios of plants along the four major geological belts in British Columbia. Non-parametric Kruskal–Wallis and pairwise Wilcox tests were used to examine whether the geological belts had statistically significant mean differences. It was found that the province could be effectively divided into east and west, with the Coastal–Intermontane and Omineca–Foreland regions having statistically different means from each other. 87Sr/86Sr ratios had statistically significant relationships with salt deposition, volcanic deposition, and mean age of the underlying lithology. Generally, 87Sr/86Sr ratios increased with distance from the coast as the atmospheric input of radiogenic strontium from marine-derived rainwater decreased and the input of radiogenic strontium isotopes from the underlying geology of the Rockies in the far east of the province increased.
  • OPEN ACCESS
    An integrated assessment of impacts to ecosystem services associated with prairie pothole wetland drainage quantifying wide-ranging losses
    FACETS • Vol. 9 • pp. 1 - 15
    In many regions, a tradeoff exists between draining wetlands to support the expansion of agricultural land, and conserving wetlands to maintain their valuable ecosystem services. Decisions about wetland drainage are often made without identifying the impacts on the services these systems provide. We address this gap through a novel assessment of impacts on ecosystem services via wetland drainage in the Canadian prairie landscape. Draining pothole wetlands has large impacts, but sensitivity varies among the indicators considered. Loss of water storage increased the magnitude of median annual flows, but absolute increases with drainage were higher for larger, less frequent events. Total phosphorus exports increased in concert with streamflow. Our analysis suggested disproportionate riparian habitat losses with the first 30% of wetland area drained. Dabbling ducks and wetland-associated bird abundances respond strongly to the loss of small wetland ponds; abundances were predicted to decrease by half with the loss of only 20%–40% of wetland area. This approach to evaluating changes to key wetland ecosystem services in a large region where wetland drainage is ongoing can be used with an economic valuation of the drainage impacts, which should be weighed against the benefits associated with agricultural expansion.
  • OPEN ACCESS
    Drivers of high rates of carbon burial in a riverine-influenced freshwater marsh in the Long Point Walsingham Priority Place of southern Ontario
    FACETS • Vol. 10 • pp. 1 - 14
    Reported rates of soil organic carbon (SOC) accumulation in wetlands are markedly higher over recent versus longer timescales, caused by SOC losses through decomposition, paleoenvironmental changes, and recent increases in sedimentation or biomass production. Explaining changes in SOC sequestration rates and determining the time horizon over which high rates are sustained are both critical for accurately measuring the potential for wetland conservation as a natural climate solution. Here, we present analyses on a 4-m core from a riverine-influenced marsh in Big Creek watershed, southern Ontario, to track changes in SOC accumulation regimes. Since wetland initiation ∼5700 years ago, mean long-term (pre-industrial) rates of SOC accumulation were 24 g C m−2 year−1, and recent rates up to four times higher. We demonstrate that elevated recent rates of SOC accumulation are largely explained by more labile carbon in surficial soils, and are sustained for less than a century before transitioning to slower burial rates of predominantly recalcitrant organic matter. However, there are exceptions to this trend, such as when labile SOC was buried intermittently during Holocene Lake Erie highstands. Our research underscores the importance of organic matter type and hydroclimatic context in predicting long-term potential for marsh soils to stabilize atmospheric carbon.
  • OPEN ACCESS
    Data and knowledge needs for improving science and policy for peatlands in Canada in a changing world: insights from Global Peatlands Initiative Workshop, June 2023
    FACETS • Vol. 10 • pp. 1 - 19
    Knowledge and data on the current function, future threats, and benefits of peatlands in Canada are required to support evidence-based decision-making to ensure they continue to provide critical ecosystem services. This is particularly relevant for Canada, given the large expanse of relatively intact peatland area. There is a need, not only to standardize protocols, but also to prioritize types of information and knowledge that can best meet conservation and management goals. This was the challenge posed to the participants of the Global Peatlands Initiative workshop in June 2023 in Quebec City, Quebec, Canada. Participants were composed of researchers using primarily Western science approaches that use peatland data for carbon accounting, policy or sustainable land use, reclamation/restoration, conservation, wildlife, and water resources applications. For seven peatland data categories (hydrometeorological and environmental sensing; peat coring and depth; greenhouse gas monitoring; biodiversity; vegetation, woody debris, and litter; Traditional Knowledge; water quality), three priority measurements were identified and recommendations for their collection were discussed. The key recommendations from the workshop were to (1) create standardized, yet flexible protocols; (2) coordinate field data collection where possible; (3) weave more Traditional Knowledge into understanding of peatlands; (4) create an atlas of existing peatland information; (5) scope opportunities to create a network of peatland “super sites”.
  • OPEN ACCESS
    An ensemble machine learning bioavailable strontium isoscape for Eastern Canada
    FACETS • Vol. 10 • pp. 1 - 17
    Bioavailable strontium isotope ratios (87Sr/86Sr) distribution across the landscape mainly follow the underlying lithology, making 87Sr/86Sr baseline maps (isoscapes) powerful tools for provenance studies. 87Sr/86Sr has already been used in Eastern Canada (EC) to track food and human remains origins, or to reconstruct animal mobility. While bioavailable 87Sr/86Sr isoscapes for EC can be extrapolated from global datasets using random forest modelling (RF), no regionally calibrated isoscape exists. Here, we produce a regionally calibrated bioavailable 87Sr/86Sr isoscape by analysing plants collected at 136 sites across EC, incorporating updated geological variables and applying a novel ensemble machine learning (EML) framework. We generated and compared isoscapes generated by the traditional RF and the EML approaches. Adding local bioavailable 87Sr/86Sr to a global dataset significantly improved the model prediction with a drastic increase of predicted 87Sr/86Sr and increased spatial uncertainty in the northern Canadian craton. EML produced similar 87Sr/86Sr predictions but with tighter spatial uncertainty distribution. Regionally calibrated RF and EML isoscapes significantly outperformed the global bioavailable RF isoscape, confirming the requirement for collecting local data in data-poor regions. This isoscape provides a baseline in EC to monitor and manage the movements and provenance of agricultural products, natural resources, endangered/harmful migratory species, and archaeological human remains and artifacts.