Sun Gro Horticulture - Avenir, Alberta

Avenir Bog

The Avenir study area is a newly extracted forested continental bog with one peat extraction field and an undisturbed natural site serving as a reference. The bog was cleared and ditched starting in 2019, with vacuum extraction activities commencing in late summer 2020. It is located approximately 210 km north of Edmonton (54.992349, -112.412725) (Figure 5.). The mean annual temperature is 1.6 °C and average precipitation is 443 mm per year.

The vegetation in the adjacent undisturbed site is predominantly bog and poor fen vegetation dominated by Picea mariana, Sphagnum spp., and intermittent Larix laricina and feathermoss species. The soils are typic mesisols sitting on parent material composed of clay-rich moraine and organic deposits. The peat depth ranges from 0.75 m to 2.65 m.

Regular ditch maintenance to facilitate drainage and allow for extraction activities occurred during the spring, summer, and fall months of 2020 and 2021. This extracted peatland is considered "young" in this study because it was recently opened.

Sun Gro Horticulture - Seba Beach, Alberta

Seba Beach Peatland Complex

The Seba Beach facility has been active since 1975, with vacuum harvesting ongoing since 1980. The study area is located approximately 100 km west of Edmonton ( 53.480001, -114.861784) and has a mean annual temperature of 3.0 °C and average precipitation of 508 mm per year (Figure 5.). Prior to development, the peatland was classified as a forested continental bog.

There are multiple extraction and restored sites occurring simultaneously at this facility:

• One natural site (undisturbed, used as a reference) (Figure 14.)

• Two peat extraction sites (Figure 10., Figure 11.)

  • Field 16 - Active peat extraction ("mature" peatland)

  • Field 12 - Peat no longer extracted but restoration has not commenced ("complete" peatland)

• Two restored sites (Figure 12. , Figure 13.)

  • Field 16 - One perimeter ditch is not blocked, soil is not saturated to the surface

  • Field 5 - All ditches are blocked, soil is saturated to the surface

The vegetation in the adjacent undisturbed site is typical of bog and poor fen peatlands. The dominant vegetation at the Seba Beach study area is Picea mariana and Sphagnum spp., with pockets of Larix laricina and feathermoss species. The soils are typic mesisols and have parent material composed of clay-rich moraine and organic deposits. The peat depth ranges from 0.75 m to over 4 m across the study area.

Ditches within and between extracted sites were continuously cleared during active extraction to facilitate drainage and allow for peat extraction activities. At Field 12, extraction operations ceased in fall 2020 and ditches were blocked in summer 2021 in preparation for future restoration efforts. Extraction operations are ongoing in Field 16.

Ditches within the restored area were blocked and the water table was allowed to rise in Field 5 during summer of 2018, and in a portion of Field 16 in the fall of 2019. Due to its close proximity to the extracted area in Field 16, the perimeter ditch surrounding the north section of the Field 16 restoration site was not blocked. This has resulted in a partially lowered water table and unsaturated soil conditions. Restoration sites were revegetated with moss propagules using the moss layer transfer technique from an adjacent donor site, amended with phosphate fertilizer, and protected with straw mulch in the fall of 2019 and spring of 2020. Vegetation at both restoration sites is dominated by Eriophorum spp., Carex spp., Sphagnum spp., and Polytricum strictum.

Plant root simulator (PRS) probes

Sampling Proceedure and Experimental Design

Plant root simulator (PRS) probes measuring ammonium (NH4-N) and nitrate (NO3-N) were used to assess the relative rate of nutrients and major ions available for root and microbial uptake per surface area over a known time in the top 5-10 cm of the peat surface at both peatlands (Harris et al., 2020; Munir et al., 2017) (Figure 24.). A systematic, stratified sampling design was used to conduct transects within undisturbed, extracted, and restored peat fields varying in age and restoration technique (Figure 15.). A random design was not selected due to site operational constraints based on location accessibility and required equipment access that would disrupt the study. A systematic design was selected to cover as much area as possible within these constraints and to encourage measuring the natural variability within each extraction treatment.

Sites were spaced approximately 20 m apart in natural, extracted field 12 ("complete"), and restored locations, with a randomly assigned transect starting point and direction where operationally possible (Figure 15.). Each site was comprised of 3 locations spaced 5 meters apart (Figure 15.). In the extraction areas undergoing active extraction (Seba field 16 ("mature") and Avenir ("young")), sites were spread evenly along the length and width of the site ditch to cover as much area as possible; sites were placed 1.5 m in from the ditch edge (Figure 15.). Sites were selected along the ditch because ongoing peat extraction with heavy equipment prevented site placement away from ditches. A 30 m temperature and soil moisture transect across the width of the peat field (encompassing the ditch edge, centre of the field, and the following ditch edge) was conducted prior to the study and showed negligible differences in temperature and soil moisture within the top 10 cm. Thus, the site locations along the ditch edge were determined to be adequately representative of the peat field surface.

Measurement Protocols

Five samples, comprised of three anions and three cations each, were installed in both hummocks and hollows at the non-extraction sites, and in each extraction phase to assess variability between extraction phases (Figures 16. - 23.). At each probe location, a steel rod was inserted into the peat to observe rust accumulation as an indicator of reduction-oxidation conditions at the time of retrieval (Owens et al., 2008) (Figure 25.). Soil moisture at 6 cm below the ground, surface temperature, and peat temperature 10 cm below the ground were measured during installation and at the time of retrieval. A sturdy, steel rod was inserted into the peat to determine the presence of ice. Depth of rust and soil moisture were selected to estimate the aeration and redox conditions at each site. Surface temperature was measured to measure the effect of shading from the presence or absence of vegetation and soil temperature below the ground was recorded to characterize temperatures favorable for microbial activity. Depth of ice was selected to estimate the presence of cool temperatures at depth, and as an indicator of an impermeable layer that may impede vertical water movement and increase soil moisture conditions.

Water Chemistry

Sampling Procedure and Experimental Design

Water chemistry samples measuring electrical conductivity (EC), pH, NH4-N, and NO3-N were collected at surface pools, shallow wells, drainage ditches, and site outflow locations at undisturbed (natural), extracted, and restored peatlands. Samples were collected on three instances while the PRS probes were installed: at installation, halfway through the installation period, and when the probes were removed. Previously established sampling locations in the area near the PRS probes were used in order to tie into an existing multi-year chemistry dataset.

Water chemistry was collected at outflow locations for each peat extraction phase. Water temperature was measured in situ to observe any differences due to shading or low water volume that may have an impact on microbial activity and subsequent nutrient availability. Where the landscape was extremely flat, ditches are often incised into the underlying mineral in order to be deep enough to drain the peatland. Water moving in a ditch comprised of peat versus mineral can take on different chemical properties due to contact with different substrates. With this in mind, ditch composition was noted when sampling, and care was taken to obtain representative samples of peat and mineral ditch substrate (Figures 26. & 27.).

Measurement Protocols

Electrical conductivity (EC), pH, and water temperature were measured on site using a combination pH and EC probe by Hanna Instruments. For NH4-N and NO3-N, samples were collected in HDPE bottles triple-rinsed with the sample water. Filled bottles were kept cool and submitted for analysis within 48 hours of sampling. Samples were filtered with 0.45 μm cellulose acetate syringe filters and analysed using a Lachat QuickChem QC8500 FIA automated ion analyzer.

Data manipulation and statistical analyses were conducted in RStudio (v1.4.1717), using R Statistical Software (v.4.1.1; R Core team, 2021). Data was manipulated and graphed using the tidyverse R package (v1.3.1; Wickham et al., 2019).

To reduce the complexity of the data, nonmetric multidimensional scaling (NMDS) was selected to visualize the relationships between the PRS and physicochemical parameters, and for the outflow water chemistry between peat extraction phases. Data were scaled and a Euclidean distance metric was used. NMDS is a non-parametric, distance-based approach, and was selected because the data did not meet assumptions necessary for parametric techniques. Stress values associated with both NMDS ordinations were stable. PCA and discriminant analysis were used during initial data analysis; however the NMDS was selected for the final analysis to minimize any assumption violations and to reduce the chance of variables being excluded from the ordination. Similar trends were observed using all three techniques.

The majority of the data analysis associated with this project is descriptive. However, to assess the proportion of variance explained by peat extraction phases, a perMANOVA analysis with 999 permutations using Euclidean distance was selected. Pairwise comparisons adjusted for multiple inference were used to correct p-values (alpha = 0.05) obtained from the perMANOVA analysis.