DOI: 10.5061/dryad.2280gb5xb
title: Establishing peat-forming plant communities: A comparison of wetland reclamation methods in Alberta's oil sands region

description: The Sandhill Wetland (SW) and Nikanotee Fen (NF) are two wetland research
 projects designed to test the viability of peatland reclamation in the
 Alberta oil sands post-mining landscape. To identify effective approaches
 for establishing peat-forming vegetation in reclaimed wetlands, we
 evaluated how plant introduction approaches and water level gradients
 influence species distribution, plant community development, and
 establishment of bryophyte and peatland species richness and cover. Plant
 introduction approaches included seeding with a Carex aquatilis-dominated
 seed mix, planting C. aquatilis and J. balticus seedlings, and spreading a
 harvested moss layer transfer. Establishment was assessed six years after
 introduction at SW and five years after introduction at NF. A total of 51
 species were introduced to the reclaimed wetlands, and 122 species were
 observed after five and six years. The most abundant species in both
 reclaimed wetlands was C. aquatilis, which produced dense canopies and
 occupied the largest water level range of observed plants. Introducing C.
 aquatilis also helped to exclude marsh plants such as Typha latifolia that
 has little to no peat accumulation potential. Juncus balticus persisted
 where the water table was lower and encouraged formation of a diverse
 peatland community and facilitated bryophyte establishment. Various
 bryophytes colonized suitable areas, but the moss layer transfer increased
 cover of desirable peat-forming mosses. Communities with the highest
 bryophyte and peatland species richness and cover (averaging 9 and 14
 species, and 50% to 160% cover respectively) occurred where summer water
 level was between -10 and -40 cm. Outside this water level range, a marsh
 community of Typha latifolia dominated in standing water and a wet-meadow
 upland community of Calamagrostis canadensis and woody species established
 where the water table was deeper. Overall, the two wetland reclamation
 projects demonstrated that establishing peat-forming vascular plants and
 bryophytes is possible, and community formation is dependent upon water
 level and plant introduction approaches. Future projects should aim to
 create microtopography with water tables within 40 cm of the surface and
 introduce vascular plants such as J. balticus that facilitate bryophyte
 establishment and support development of a diverse peatland plant
 community.
description: <strong>Study Region</strong> The
 Sandhill Wetland (SW) and Nikanotee Fen (NF) are located north of Fort
 McMurray, Alberta, Canada. Mean total annual precipitation in Fort
 McMurray is 419 mm, with mean annual rainfall of 316 mm and snowfall of
 134 cm. Daily mean temperatures dip to -17.4<sup>o</sup> C in
 January and peak at 17.1<sup>o</sup> C in July (1981-2010
 climate normal from weather station at 56° 39’ N, 111° 13’ W; Environment
 Canada 2018a). The data reported here were collected in the summer of
 2017, when total annual precipitation was 312 mm and daily mean July
 temperature averaged 22.9<sup>o</sup> C. (daily data report
 for 2017 from weather station at 56° 39’ N, 111° 13’ W; Environment Canada
 2018b). <strong>Vegetation
 Sampling</strong> Vegetation composition was
 sampled and depth to water measured in 79 plots at SW and 42 plots at NF
 in July 2017. Canopy cover by species was assessed by visual estimation to
 the nearest 5 % in an 8 m<sup>2</sup> circular plot at SW and
 to the nearest 1 % in a 4 m<sup>2</sup> square plot at NF. The
 sampled area represents 0.37% of the total wetland area at SW (632
 m<sup>2</sup> of 17 ha) and 0.76% of the total fen area of NF
 (168 m<sup>2</sup> of 2.2 ha).  Plot sizes differed due to
 original sampling protocols at each fen, but are both within recommended
 plot sizes for low-growing (bryophyte) and herbaceous vegetation (4 – 16
 m<sup>2</sup>; Chytrý and Otýpková 2003). Species-area
 relationships assume that species richness increases with increased
 sampling area (Connor and McCoy 1979); however, species richness was
 higher in 4 m<sup>2</sup> plots at NF (mean = 16 species, se =
 1.2) than at SW in 8 m<sup>2</sup> plots (mean = 9 species, se
 = 0.7). In addition, Otýpková and Chytrý (2006) showed that ordinations
 containing differently sized plots (of less than a factor of four) do not
 produce patterns associated with plot size. The data
 represent the sixth-year post-introduction at SW (2012 to 2017) and
 fifth-year post-introduction at NF (2013 to 2017). Despite the difference
 in number of growing seasons, establishment outcomes by 2017 are
 relatively equivalent because of the different propagule growth
 stages. Latin and common names for vascular plants
 follow the Alberta Conservation Information Management System (ACIMS 2017,
 2018), mosses follow Flora of North America Editorial Committee (FNA 2007,
 2014), and Stotler and Crandall-Stotler (1977) for liverworts.
 Depth to water was measured in an open pit dug adjacent to each
 vegetation plot during the 2017 sampling. Total precipitation in Fort
 McMurray during the days between the survey dates was negligible at 9 mm
 (local weather station at 56o 39’ N, 111<sup>o</sup> 13’ W;
 Environment Canada 2018b).
 <strong>Analysis</strong> Species
 were classified as ‘peatland’, ‘marsh-swamp’, ‘upland’, or ‘widespread’
 based on habitat type designations obtained primarily from the Alberta
 Wetland Classification System (AWCS; ESRD 2013) for vascular plants, and
 Vitt and House (2015) and Vitt et al. (2023) for bryophytes. The
 Reclamation Criteria for Well Sites and Associated Facilities for
 Peatlands (Environment and Parks 2017), the National Wetland Plant List
 (USACE 2018), and the Flora of North America (FNA 2007, 2014) were used in
 support. Habitat classifications are not static as many plants occur
 across multiple habitat types. Priority was given to the ‘peatland’
 classification even if the species was not an obligate peatland species
 and may occur in other habitat types. Species designated as ‘marsh-swamp’
 typically are found in mineral soil wetlands and are not known to occur in
 peatlands. Wet meadow species occur on mineral soil in the transition area
 between an upland and marsh were also classified as ‘marsh-swamp’. Species
 designated as ‘upland’ are not known to occur in wetlands. If the species
 is not strongly associated with one particular habitat type and can occur
 from uplands to wetlands, it was classified as ‘widespread’.
 Rank abundance curves were calculated to assess the relative
 proportion of each species within each plant introduction approach (Kindt
 and Coe 2005). Best fit regressions for species distribution along the
 water level gradient at each wetland were determined by selecting the most
 parsimonious model with the lowest Akaike information criterion (AIC)
 value (Akaike 1987, Burnham et al. 2011). Analyses were performed in R
 using the Stats and BiodiversityR  packages (R Core Team 2018).
 For multivariate analyses, species abundance data were
 relativized by plot total and square root transformed to downweight the
 contribution of dominant species. Plots were then compared using
 Bray-Curtis similarity (Bray and Curtis 1957) and analyzed using a
 non-metric multidimensional scaling ordination (NMDS). Two NMDS
 ordinations were produced, one NMDS to evaluate change over time from the
 initial plant composition in each plant introduction approach and the
 plant composition data from 2017, and a second NMDS with only the data
 from 2017 to compare plots and communities across the reclaimed wetlands.
 A solution for the NMDS ordination with all data years was reached in 2
 dimensions after 50 iterations with a stress value of 0.12. The trajectory
 distance between plots across years was calculated on a 2D coordinate
 plane. A solution for the 2017 NMDS ordination was reached in 2 dimensions
 after 50 iterations with a stress value of 0.14. A permutational
 multivariate analysis of variance (PERMANOVA; Anderson et al. 2008) using
 Type II sums of squares was conducted to assess multivariate differences
 between plant introduction approaches and in response to water level.
 Communities were identified using a group average cluster analysis with a
 cut-off level of 47% similarity, determined by similarity profile analysis
 (SIMPROF) (Appendix 1: Figure S1). The SIMPROF test provides statistically
 significant evidence of groups in samples. The 47% cut-off level was
 ultimately selected to obtain the most parsimonious solution that
 minimized the number of outlier samples and maximized the similarity
 between clustered groups. A similarity percentages analysis (SIMPER)
 identified the species contributing most to the similarities and
 differences between groups. Diversity within communities was calculated as
 species richness, the total number of species in each plot, and the
 average multivariate dispersion of plots from the group (community)
 centroid (PERMDISP), where higher average dispersion (Bray-Curtis
 distance) indicates more variability in the assemblage composition
 (Anderson et al. 2008). Multivariate dispersions from the group centroid
 are directly interpretable as beta diversity among groups, which may be
 defined as the variability in species composition among sampling units for
 a given area at a given spatial scale (Anderson 2006, Anderson et al.
 2006). Differences between variables were not determined statistically due
 to unequal sample sizes within communities. All multivariate analyses were
 conducted in Primer 7, Version 7.0.21, and with PERMANOVA +1 (Primer-E
 Ltd.; Anderson et al. 2008, Clarke and Gorley 2015). We
 used published reclamation criteria for peatlands in Alberta (Environment
 and Parks 2017) to assess whether the vegetation composition six- and
 five-years post-introduction would achieve reclamation certification from
 AER. For reclaimed fens from bare soil, the target criteria for each
 relevant vegetation assessment component include: 
 bryophyte canopy cover ≥ 50 %;  peatland
 (desirable fen) species canopy cover ≥ 50 %; 
 non-peatland (marsh-swamp, upland, or widespread) species canopy
 cover ≤ 20 %; and  peatland plant species richness of
 ≥ 4 for saline fens. Species introduction
 approaches include:  Spreading a native
 seed mix dominated by Carex aquatilis (CaSdMx-SW)
 Carex aquatilis seedlings (Ca-NF), Juncus
 balticus seedlings (Ju-NF), C. aquatilis seedlings
 and MLT (moss layer transfer) (Ca-MLT-NF), J.
 balticus seedlings and MLT (Ju-MLT-NF), and MLT
 (MLT-NF).  Dataset and metadata that
 describe the abbreviated terms used in the dataset are
 available.
description: # SWNF\_master\_df\_allyrs\_2023-08-11.csv *** ## Summary of dataset
 contents: The dataset contains abiotic and biotic variables measured in
 2017 at the Sandhill Wetland and the Nikanotee Fen. ## Description of the
 Data and file structure The data is structured with plots as rows and
 abiotic and biotic variables as columns. A metadata tab is included in the
 file to explain abbreviated variable names. ## Sharing/access Information
 This is the only location that this data is available.