Environ Monit Assess (2020) 192: 743 https://doi.org/10.1007/s10661-020-08645-z A protocol for monitoring plant responses to changing nitrogen deposition regimes in Alberta bogs Dale H. Vitt & Melissa House & Samantha Kitchen & R. Kelman Wieder Received: 20 April 2020 /Accepted: 28 September 2020 /Published online: 2 November 2020 # The Author(s) 2020 Abstract Bogs are nutrient poor, acidic ecosystems that to future environmental inputs of nutrients and provide a receive their water and nutrients entirely from precipita- structured means for collecting annual data. The proto- tion (= ombrogenous) and as a result are sensitive to col centers on measurement of five key plant/lichen nutrient loading from atmospheric sources. Bogs occur attributes, including changes in (1) plant abundances, frequently on the northern Alberta landscape, estimated (2) dominant shrub annual growth and primary produc- to cover 6% of the Athabasca Oil Sands Area. As a tion, (3) lichen health estimated through chlorophyll/ result of oil sand extraction and processing, emissions of phaeophytin concentrations, (4) Sphagnum annual nitrogen (N) and sulfur (S) to the atmosphere have led to growth and production, and (5) annual growth of the increasing N and S deposition that have the potential to dominant tree species (Picea mariana). We placed five alter the structure and function of these traditionally permanent plots in each of six bogs located at different nutrient-poor ecosystems. At present, no detailed proto- distances from the center of oil sand extraction and col is available for monitoring potential change of these sampled these for 2 years (2018 and 2019). We com- sensitive ecosystems. We propose a user-friendly proto- pared line intercept with point intercept plant assess- col that will monitor potential plant and lichen responses ments using NMDS ordination, concluding that both methods provide comparable data. These data indicated that each of our six bog sites differ in key species Electronic supplementary material The online version of this abundances. Structural differences were apparent for article (https://doi.org/10.1007/s10661-020-08645-z) contains supplementary material, which is available to authorized users. the six sites between years. These differences were mostly driven by changes in Vaccinium oxycoccos,not : : D. H. Vitt (*) M. House S. Kitchen the dominant shrubs. We developed allometric growth School of Biological Sciences, Southern Illinois University, equations for the dominant two shrubs (Rhododendron Carbondale, IL 62901, USA e-mail: [email protected] groenlandicum and Chamaedaphne calyculata). Equa- tions developed for each of the six sites produced R. K. Wieder growth values that were not different from one another Department Biology, Villanova University, Villanova, PA 19085, nor from one developed using data from all sites. An- USA nual growth of R. groenlandicum differed between sites, R. K. Wieder but not years, whereas growth of C. calyculata differed Center for Biodiversity and Ecosystem Stewardship, Villanova between the 2 years with more growth in 2018 com- University, Villanova, PA 19085, USA pared with 2019. In comparison, Sphagnum plant den- R. K. Wieder sity and stem bulk density both had strong site differ- Faculty of Science and Technology, Athabasca University, ences, with stem mass density higher in 2019. When Athabasca, Alberta, Canada combined, annual production of S. fuscum was greater 743 Page 2 of 25 Environ Monit Assess (2020) 192: 743 − in 2019 at three sites and not different at three of the N, NO3 -N, and/or dissolved inorganic N concentra- sites. Chlorophyll and phaeophytin concentrations from tions (DIN) in bog porewaters (e.g., Berendse et al. the epiphytic lichen Evernia mesomorpha also differed 2001; Bragazza and Limpens 2004; Bragazza et al. between sites and years. This protocol for field assess- 2005; Gunnarsson and Rydin 2000;Gunnarssonetal. ments of five key plant/lichen response variables indi- 2004; Hoosbeek et al. 2002; Lamers et al. 2000; cated that both site and year are factors that must be Limpens and Berendse 2003; Limpens et al. 2003; accounted for in future assessments. A portion of the site Wiedermann et al. 2008). In eastern North America, at variation was related to patterns of N and S deposition. Mer Bleue bog in eastern Ontario, after 5 years of N fertilization, Bubier et al. (2007) reported an increase in Keywords Allometric equation . Atmospheric vascular plant cover and decease in Sphagnum abun- deposition .Bog .Boreal .Nitrogen .Peatland .Oilsands . dance. However, all of these studies were done in areas Sphagnum where ambient levels of N deposition have been signif- icantly higher than those found in western Canada. In addition, many studies have shown that lichens, espe- Introduction cially fruticose growth forms, are among the most sen- sitive components of vegetation to increasing N inputs Bogs are Sphagnum-dominated, acidic, nutrient poor, (e.g., Gilbert 1986; Van Dobben et al. 2001). peat-accumulating ecosystems found in subarctic, bore- The Oil Sands Administrative Area in northern Al- al, and cool-temperate regions, mainly in the northern berta occupies 140,329 km2 with bogs covering 6% of hemisphere (Vitt 2006). In western Canada, they cover the area (Wieder et al. 2016b). Atmospheric deposition 365,157 km2 (or about 20%) of the land surface in of N is low in the region (< 1 kg N ha−1 year−1; Hember Alberta, Saskatchewan, and Manitoba (Vitt et al. 2018;Wiederetal.2016a); however, oil sand develop- 2000). Hydrologically, bogs are ombrogenous, receiv- ment north of Fort McMurray, Alberta, has led to in- ing water and nutrient inputs only from atmospheric creasing N deposition with values as high as sources and have naturally low nutrient and base cation 17 kg N ha−1 year−1 (Fenn et al. 2015;Wiederetal. levels. In pristine areas, nutrient inputs are completely 2016a). These high values of atmospherically deposited absorbed and utilized in growth by the plants and li- N have the potential to alter the structure and function of chens occupying the bog ecosystem (Wieder et al. these traditionally nutrient-poor ecosystems; however, 2019). Species richness is low, and plant communities no detailed protocol is available for monitoring potential exhibit high species similarity across sites (Vitt et al. change of these sensitive ecosystems. Although the 1995a). All bogs in continental Canada have a canopy Alberta Biodiversity Monitoring Institute has a dominated by one tree species, Picea mariana, a shrub province-wide program to track Alberta’swildlifeand layer of 5–6 species of Ericaceae and dominated by their habitats, and tracks the health of many species either Rhododendron (Ledum) groenlandicum or (ABMI 2017), the program is not designed to assess Chamaedaphne calyculata, and a hummocky ground ecosystem changes on an annual basis. Furthermore, layer mostly dominated by one species of peat moss - bogs are only a small part of their broad program. We Sphagnum fuscum (Vitt et al. 1995a). Fruticose lichens are aware of only two studies that aimed to track the (especially Evernia mesomorpha and Usnea spp.)are change of vegetation through time in wetland plant abundant on tree branches (Vitt 2006). These species- communities, and both of these determined vegetation poor plant communities are sensitive to environmental change after restoration of bogs recovering from horti- changes and, owing to their ombrogenous water source, cultural peat mining in eastern Canada (Poulin et al. are especially sensitive to nutrient loading from atmo- 2013; Rochefort et al. 2013). spheric sources (Wieder et al. 2019). Previous research at a bog near Mariana Lakes, Al- Research in European bogs has shown that increasing berta, experimentally added N over a 5-year time period −1 --1 atmospheric nitrogen (N) deposition leads to changes in (atlevelsupto25kgNha year ,asNH4NO3 in ecosystem structure and function, including altered simulated rainfall) At the higher levels, Sphagnum growth and species composition of Sphagnum mosses, fuscum net primary production (NPP) was inhibited, increase in vascular plant abundances, increased N con- dominant shrub and Picea mariana aboveground NPP + centrations and quantities in peat, and increased NH4 - were stimulated, with increased root biomass and Environ Monit Assess (2020) 192: 743 Page 3 of 25 743 production, and Sphagnum species relative abundance (Evernia mesomorpha), can we develop a suitable tech- changed. Higher N deposition also increased the abun- nique for using lichen chlorophyll/phaeophytin ratios as dance of Rhododendron groenlandicum and Androme- an indicator of lichen health? (5) Using cranked wires how da polifolia and to vascular plants in general, with an variable is annual growth and NPP of Sphagnum?(6)Can increase in shrub leaf N concentrations in Andromeda we use leader length of Picea mariana to assess variability polifolia, Chamaedaphne calyculata, Vaccinium in growth of this species? Here we assess the outcomes of oxycoccos (= Oxycoccus microcarpus), V. vitis-idaea, these protocols over a 2-year time period for a series of six and Picea mariana (Wieder et al. 2019). Of fundamental bog sites in northeastern Alberta, Canada, and provide importance to the N cycle in bogs, this research showed evidence of whether the variability in responses can be that biological N2-fixation greatly exceeded atmospher- related to growing season N and S deposition from oil ic N deposition as a source of new N inputs to the bog; sands activities.