Nitrogen Retention of Terricolous Lichens in a Northern Alberta Jack Pine Forest
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The Athabasca Oil Sands in Alberta, Canada, is one of the largest point sources of nitrogen oxides in Canada. There are concerns that elevated nitrogen (N) deposition will adversely impact forest ecosystems located downwind of emission sources. The role of the forest floor in regulating these potential eutrophication effects was investigated following a 5-year enrichment study in which N was applied as NH4NO3 above the canopy of a jack pine (Pinus banksiana Lamb) stand in northern Alberta close to Fort McMurray at rates ranging from 5 to 25 kg N ha−1 y−1 in addition to background deposition of approximately 2 kg N ha−1 y−1. Chemical analysis of lichen mats revealed that the N concentration in the apical (upper) lichen tissue and necrotic tissue increased with treatment. When expressed as a N pool, the fibric–humic material held the largest quantity of N across all treatments due to its relatively large mass (172–214 kg N ha−1), but there was no significant treatment effect. Soil net N mineralization and net nitrification rates did not differ among N treatments after five years of application. A 15N tracer applied to the forest floor showed that N is initially absorbed by the apical lichen (16.6% recovery), FH material (29.4% recovery), and the foliage of the vascular plant Vaccinium myrtilloides (31.7% recovery) in particular. After 2 years, the FH 15N pool size was elevated and all other measured pools were depleted, indicating a slow transfer of N to the FH material. Applied 15N was not detectable in mineral soil. The microbial functional gene ammonia monooxygenase (amoA) responsible for catalyzing the first step in nitrification was undetectable using PCR screening of mineral soil microbial communities in all treatments, and broad fungal/bacterial qPCR assays revealed a weak treatment effect on fungal: bacterial ratios in mineral soil with decreasing relative fungal abundance under higher N deposition. This work suggests that terricolous lichen mats, which form the majority of ground cover in upland jack pine systems, have a large capacity to effectively retain elevated N deposition in soil humus.
Keywordsnitrogen oil sands eutrophication lichens nitrogen saturation
This work was funded by CEMA (Cumulative Environmental Management Association). The authors would like to thank our laboratory and field staff at Trent University: Sylvie Danse, Katie Mitchell, Eric Grimm, Liam Murray, Liana Orlovskaya, and Jaqueline London. We would also like to thank our close collaborators Shanti Berryman and Justin Straker of Integral Ecology Group.
- Baptista JDC, Lunn M, Davenport RJ, Swan DL, Read LF, Brown MR, Morais C, Curtis TP. 2014. Agreement between amoA gene-specific quantitative PCR and fluorescence in situ hybridization in the measurement of ammonia-oxidizing bacteria in activated sludge. Appl Environ Microbiol 80:5901–10.CrossRefGoogle Scholar
- Bobbink R, Hicks K, Galloway J, Spranger T, Alkemade R, Ashmore M, Bustamante M, Cinderby S, Davidson E, Dentener F, Emmett B, Erisman JW, Fenn M, Gilliam F, Nordin A, Pardo L, De Vries W. 2010. Global assessment of nitrogen deposition effects on terrestrial plant diversity: a synthesis. Ecol Appl 20:30–59.CrossRefGoogle Scholar
- Canada E. 2011. Station results—historical data. http://climate.weather.gc.ca/climateData/dailydata_e.html?StationID=27216. Accessed June 2015.
- Cornelissen JHC, Callaghan TV, Alatalo JM, Michelsen A, Graglia E, Hartley AE, Hik DS, Hobbie SE, Press MC, Robinson CH, Henry GHR, Shaver GR, Phoenix GK, Jones DG, Jonasson S, Chapin FS, Molau U, Neill C, Lee JA, Melillo JM, Sveinbjörnsson B, Aerts R. 2001. Global change and arctic ecosystems: is lichen decline a function of increases in vascular plant biomass? J Ecol 89:984–94.CrossRefGoogle Scholar
- Fenn ME, Nagel HD, Koseva I, Aherne J, Jovan SE, Geiser LH, Schlutow A, Scheuschner T, Bytnerowicz A, Gimeno BS, Yuan F, Watmough SA, Allen EB, Johnson RF, Meixnert T. 2014. A comparison of empirical and modelled nitrogen critical loads for mediterranean forests and shrublands in California. Nitrogen Depos Crit Loads Biodivers Proc Int Nitrogen Initiat Work Link Expert Conv Long-Range Transbound Air Pollut Conv Biol Divers. pp 357–68.Google Scholar
- Glass NL, Donaldson GC. 1995. Development of primer sets designed for use with the PCR to amplify conserved genes from filamentous ascomycetes. Appl Environ Microbiol 61:1323–30.Google Scholar
- Neuwirth E. 2014. RColorBrewer: ColorBrewer palettes. R Package version 11–2:https://cran.R-project.org/package=RColorBrewer. Accessed Aug 2017.
- Nihlgard B. 1985. The ammonium hypothesis: an additional explanation to the forest dieback in Europe. Ambio 14:2–8.Google Scholar
- Pardo LH, Templer PH, Goodale CL, Duke S, Groffman PM, Adams MB, Boeckx P, Boggs J, Campbell J, Colman B, Compton J, Emmett B, Gundersen P, Kjønaas J, Lovett G, Mack M, Magill A, Mbila M, Mitchell MJ, McGee G, McNulty S, Nadelhoffer K, Ollinger S, Ross D, Rueth H, Rustad L, Schaberg P, Schiff S, Schleppi P, Spoelstra J, Wessel W. 2006. Regional assessment of N saturation using foliar and root δ15N. Biogeochemistry 80:143–71.CrossRefGoogle Scholar
- Phoenix GK, Emmett BA, Britton AJ, Caporn SJM, Dise NB, Helliwell R, Jones L, Leake JR, Leith ID, Sheppard LJ, Sowerby A, Pilkington MG, Rowe EC, Ashmore MR, Power SA. 2012. Impacts of atmospheric nitrogen deposition: responses of multiple plant and soil parameters across contrasting ecosystems in long-term field experiments. Glob Change Biol 18:1197–215.CrossRefGoogle Scholar
- R Core Team. 2017. R: a language and environment for statistical computing. R Found Stat Comput. Vienna, Austria. https://www.R-project.org. Accessed Nov 2017.
- Robinson D. 2017. broom: convert statistical analysis objects into tidy data frames. R package version 0.4.3.Google Scholar
- Rotthauwe JH, Witzel KP, Liesack W. 1997. The ammonia monooxygenase structural gene amoA as a functional marker: molecular fine-scale analysis of natural ammonia-oxidizing populations. Appl Environ Microbiol 63:4704–12.Google Scholar
- Soil Classification Working Group. 1998. The Canadian System of Soil Classification. Can Syst Soil Classif, 3rd ed, Agric Agri-Food Canada Publ 1646:187.Google Scholar
- Stephen JR, Chang YJ, Macnaughton SJ, Kowalchuk GA, Leung KT, Flemming CA, White DC. 1999. Effect of toxic metals on indigenous soil β-subgroup proteobacterium ammonia oxidizer community structure and protection against toxicity by inoculated metal-resistant bacteria. Appl Environ Microbiol 65:95–101.Google Scholar
- Templer PH, Mack MC, Chapin FS, Christenson LM, Compton JE, Crook HD, Currie WS, Curtis CJ, Dail DB, D’Antonio CM, Emmett BA, Epstein HE, Goodale CL, Gundersen P, Hobbie SE, Holland K, Hooper DU, Hungate BA, Lamontagne S, Nadelhoffer KJ, Osenberg CW, Perakis SS, Schleppi P, Schimel J, Schmidt IK, Sommerkorn M, Spoelstra J, Tietema A, Wessel WW, Zak DR. 2012. Sinks for nitrogen inputs in terrestrial ecosystems: a meta-analysis of 15N tracer field studies. Ecology 93:1816–29.CrossRefGoogle Scholar
- Tuominen Y. 1967. Studies on the strontium uptake of the Cladonia alpestris thallus. In: Annales Botanici Fennici. JSTOR. pp 1–28.Google Scholar
- Watmough SA, Bird A, Mcdonough A, Grimm E. 2018. Forest fertilization associated with oil sands emissions. Ecosystems 1–14. https://doi.org/10.1007/s10021-018-0249-x.
- Wickham H. 2016. ggplot2. Create elegant data visualizations using the grammar of graphics. R package version 2.1.0. https://cran.r-project.org/web/packages/ggplot2/index.html. Accessed June 2016.