, Volume 13, Issue 2, pp 194–204 | Cite as

Spatial Heterogeneity in the Shrub Tundra Ecotone in the Mackenzie Delta Region, Northwest Territories: Implications for Arctic Environmental Change

  • Trevor C. Lantz
  • Sarah E. Gergel
  • Steven V. Kokelj


Growing evidence suggests that plant communities in the Low Arctic are responding to recent increases in air temperature. Changes to vegetation, particularly shifts in the abundance of upright shrubs, can influence surface energy balance (albedo), sensible and latent heat flux (evapotranspiration), snow conditions, and the ground thermal regime. Understanding fine-scale variability in vegetation across the shrub tundra ecotone is therefore essential as a monitoring baseline. In this article, we use object-based classifications of airphotos to examine changes in vegetation characteristics (cover and patch size) across a latitudinal gradient in the Mackenzie Delta uplands. This area is frequently mapped as homogenous vegetation, but it exhibits fine-scale variability in cover and patch size. Our results show that the total area and size of individual patches of shrub tundra decrease with increasing latitude. The gradual nature of this transition and its correlation with latitudinal variation in temperature suggests that the position of the shrub ecotone will be sensitive to continued warming. The impacts of vegetation structure on ecological processes make improved understanding of this heterogeneity critical to biophysical models of Low Arctic ecosystems.


Low Arctic object-oriented object-based climate change airphotos vegetation classification 



The authors thank Sarah Borgart, Stephen Schwarz, Marcella Snijders, Matt Tomlinson, and Rory Tooke. We would also like to thank Greg Henry, Isla Myers-Smith, Nicholas Coops, and two anonymous reviewers for helpful comments on drafts of this manuscript. Funding support was received from Aurora Research Institute (Research Fellowship), Canon USA and the AAAS (Canon National Parks Science Scholarship), Global Forest Research (Research Grant GF-18-2004-212), Indian and Northern Affairs Canada (Cumulative Impact Monitoring Program, Water Resources Division, the Northern Science Training Program, and the Mackenzie Valley Airphoto Project), Killiam Trusts (Predoctoral Fellowship), Natural Resources Canada (Polar Continental Shelf Program), Natural Sciences and Engineering Research Council of Canada (PGS-B and Northern Internship to T. C Lantz).


  1. Anderson DR, Burnham KP, Thompson WL. 2000. Null hypothesis testing: problems, prevalence, and an alternative. J Wildlife Manag 64:912–23.CrossRefGoogle Scholar
  2. Aylsworth JM, Burgess MM, Desrochers DT, Duk-Rodkin A, Robertson T, Traynor JA. 2000. Surficial geology, subsurface materials, and thaw sensitivity of sediments. In: Dyke LD, Brooks GR, Eds. The physical environment of the Mackenzie Valley, Northwest Territories: a base line for the assessment of environmental change. Geological Survey of Canada Bulletin, vol 547. Ottawa, ON: Geological Survey of Canada. p 41–8.Google Scholar
  3. Benz UC, Hofmann P, Willhauck G, Lingenfelder I, Heynen M. 2004. Multi-resolution, object-oriented fuzzy analysis of remote sensing data for GIS-ready information. ISPRS J Photogramm Remote Sens 58:239–58.CrossRefGoogle Scholar
  4. Blaschke T, Hay GJ. 2001. Object-oriented image analysis and scale-space: theory and methods for modeling and evaluating multiscale landscape structure. Int Arch Photogramm Remote Sens 34:22–9.Google Scholar
  5. Bliss LC, Matveyeva NV. 1992. Circumpolar Arctic vegetation. In: Chapin FS, Ed. Arctic ecosystems in a changing climate: an ecophysiological perspective. San Diego: Academic Press. p 59–89.Google Scholar
  6. Bock M, Xofis P, Mitchley J, Rossner G, Wissen M. 2005. Object-oriented methods for habitat mapping at multiple scales—case studies from Northern Germany and Wye Downs, UK. J Nat Conserv 13:75–89.CrossRefGoogle Scholar
  7. Bret-Harte MS, Shaver GR, Chapin FS. 2002. Primary and secondary stem growth in arctic shrubs: implications for community response to environmental change. J Ecol 90:251–67.CrossRefGoogle Scholar
  8. Bret-Harte MS, Shaver GR, Zoerner JP, Johnstone JF, Wagner JL, Chavez AS, Gunkelman RF, Lippert SC, Laundre JA. 2001. Developmental plasticity allows Betula nana to dominate tundra subjected to an altered environment. Ecology 82:18–32.Google Scholar
  9. Burn CR. 1997. Cryostratigraphy, paleogeography, and climate change during the early Holocene warm interval, western Arctic coast, Canada. Can J Earth Sci 34:912–25.CrossRefGoogle Scholar
  10. Burn CR, Kokelj SV. 2009. The environment and permafrost of the Mackenzie Delta area. Permafrost Periglac Process 20:83–105. doi: 10.1002/ppp.642.CrossRefGoogle Scholar
  11. Chapin FS, Eugster W, McFadden JP, Lynch AH, Walker DA. 2002. Summer differences among Arctic ecosystems in regional climate forcing. J Clim 13:2002–10.CrossRefGoogle Scholar
  12. Chapin FS, McGuire AD, Randerson J, Pielke R, Baldocchi D, Hobbie SE, Roulet N, Eugster W, Kasischke E, Rastetter EB, Zimov SA, Running SW. 2000. Arctic and boreal ecosystems of western North America as components of the climate system. Global Change Biol 6:211–23.Google Scholar
  13. Chapin FS, Shaver GR, Giblin AE, Nadelhoffer KJ, Laundre JA. 1995. Responses of Arctic tundra to experimental and observed changes in climate. Ecology 76:694–711.CrossRefGoogle Scholar
  14. Chapin FS, Sturm M, Serreze MC, McFadden JP, Key JR, Lloyd AH, McGuire AD, Rupp TS, Lynch AH, Schimel JP, Beringer J, Chapman WL, Epstein HE, Euskirchen ES, Hinzman LD, Jia G, Ping CL, Tape KD, Thompson CDC, Walker DA, Welker JM. 2005. Role of land-surface changes in Arctic summer warming. Science 310:657–60.CrossRefPubMedGoogle Scholar
  15. Corns IGW. 1974. Arctic plant communities east of Mackenzie-Delta. Can J Bot 52:1731–45.CrossRefGoogle Scholar
  16. Definiens. 2006. Definiens Professional 5 User Guide. Munich: Definiens AG.Google Scholar
  17. Definiens. 2007. Definiens Developer 7 User Guide. Munich: Definiens AG.Google Scholar
  18. Dormann CF, Woodin SJ. 2002. Climate change in the Arctic: using plant functional types in a meta-analysis of field experiments. Funct Ecol 16:4–17.CrossRefGoogle Scholar
  19. Dorren LKA, Maier B, Seijmonsbergen AC. 2003. Improved Landsat-based forest mapping in steep mountainous terrain using object-based classification. For Ecol Manag 183:31–46.CrossRefGoogle Scholar
  20. ENVI. 2006. ENVI User’s Guide. Version 4.3. Boulder, CO: Research Systems, Inc.Google Scholar
  21. Epstein HE, Beringer J, Gould WA, Lloyd AH, Thompson CD, Chapin FS, Michaelson GJ, Ping CL, Rupp TS, Walker DA. 2004a. The nature of spatial transitions in the Arctic. J Biogeogr 31:1917–33.CrossRefGoogle Scholar
  22. Epstein HE, Calef MP, Walker MD, Chapin FS, Starfield AM. 2004b. Detecting changes in Arctic tundra plant communities in response to warming over decadal time scales. Global Change Biol 10:1325–34.CrossRefGoogle Scholar
  23. Euskirchen ES, Mcguire AD, Chapin FS. 2007. Energy feedbacks of northern high-latitude ecosystems to the climate system due to reduced snow cover during 20th century warming. Global Change Biol 13:2425–38.CrossRefGoogle Scholar
  24. Forest Management Institute. 1975. Vegetation types of the Lower Mackenzie and Yukon corridor. Report No. 74-40. Canadian Forest Service, Ottawa, ON.Google Scholar
  25. Gould WA, Edlund S, Zoltai S, Raynolds M, Walker DA, Maier H. 2002. Canadian Arctic vegetation mapping. Int J Remote Sens 23:4597–609.CrossRefGoogle Scholar
  26. Gould WA, Raynolds M, Walker DA. 2003. Vegetation, plant biomass, and net primary productivity patterns in the Canadian Arctic. J Geophys Res Atmos 108(D2):8167. doi: 10.1029/2001JD000948.CrossRefGoogle Scholar
  27. Hassol SJ, Ed. 2004. Arctic climate impact assessment: impacts of warming climate. Cambridge: Cambridge University Press.Google Scholar
  28. Holroyd P, Retzer H. 2005. A peak into the future: the potential landscape impacts from gas development in Northern Canada. Calgary, AB: The Pembina Institute for Appropriate Development.Google Scholar
  29. IEG. 2002. Vegetation classification and wildlife habitat suitability modeling in the Mackenzie Delta Region. Project #5003–01. Calgary, AB: Inuvialuit Environmental and Geotechnical Inc.Google Scholar
  30. Johannessen OM, Bengtsson L, Miles MW, Kuzmina SI, Semenov VA, Alekseev GV, Nagurnyi AP, Zakharov VF, Bobylev LP, Pettersson LH, Hasselmann K, Cattle AP. 2004. Arctic climate change: observed and modelled temperature and sea-ice variability. Tellus Ser A 56:328–41.CrossRefGoogle Scholar
  31. Johnstone JF, Kokelj SV. 2008. Environmental conditions and vegetation recovery at abandoned-drilling mud sumps in the Mackenzie Delta region, NWT, Canada. Arctic 61:199–211.Google Scholar
  32. Kaplan JO, Bigelow NH, Prentice IC, Harrison SP, Bartlein PJ, Christensen TR, Cramer W, Matveyeva NV, McGuire AD, Murray DF, Razzhivin VY, Smith B, Walker DA, Anderson PM, Andreev AA, Brubaker LB, Edwards ME, Lozhkin AV. 2003. Climate change and Arctic ecosystems: 2. Modeling, paleodata-model comparisons, and future projections. J Geophys Res Atmos 108(D19):8171. doi: 10.1029/2002JD002559.CrossRefGoogle Scholar
  33. Laliberte AS, Rango A, Havstad KM, Paris JF, Beck RF, McNeely R, Gonzalez AL. 2004. Object-oriented image analysis for mapping shrub encroachment from 1937 to 2003 in southern New Mexico. Remote Sens Environ 93:198–210.CrossRefGoogle Scholar
  34. Kemper JT, Macdonald SE. 2009. Effects of contemporary Winter seismic exploration on Low Arctic plant communities and permafrost. Arct Antarct Alp Res 41:228–37.CrossRefGoogle Scholar
  35. Kokelj SV, Lantz TC, Kanigan J, Smith SL, Coutts R. 2009. Origin and polycyclic behavior of tundra thaw slumps, Mackenzie Delta region, Northwest Territories, Canada. Permafrost Periglac Process 20:173–84. doi: 10.1002/ppp.642.CrossRefGoogle Scholar
  36. Lantz TC. 2008. Relative influence of temperature and disturbance on vegetation dynamics in the Low Arctic: an investigation at multiple scales. PhD Dissertation, University of British Columbia, Vancouver.Google Scholar
  37. Lantz TC, Kokelj SV. 2008. Increasing rates of retrogressive thaw slump activity in the Mackenzie Delta region, N.W.T., Canada. Geophys Res Lett 35:L06502. doi: 06510.01029/02007GL032433.CrossRefGoogle Scholar
  38. Lantz TC, Kokelj SVK, Gergel SE, Henry GHR. 2009. Relative impacts of disturbance and temperature: persistent changes in microenvironment and vegetation in retrogressive thaw slumps. Global Change Biol 15:1664–75. doi: 10.1111/j.1365-2486.2009.01917.x.CrossRefGoogle Scholar
  39. Lillesand TM, Kiefer RW, Chipman JW. 2003. Remote sensing and image interpretation. 5th edn. New York: Wiley.Google Scholar
  40. Mackay JR. 1963. The Mackenzie Delta Area, N.W.T., Geographical Branch Memoir 8. Ottawa, ON: Department of Mines and Technical Surveys.Google Scholar
  41. McGuire AD, Chapin FS, Walsh JE, Wirth C. 2006. Integrated regional changes in Arctic climate feedbacks: implications for the global climate system. Ann Rev Environ Resour 31:61–91.CrossRefGoogle Scholar
  42. McGuire AD, Wirth C, Apps M, Beringer J, Clein J, Epstein H, Kicklighter DW, Bhatti J, Chapin FS, de Groot B, Efremov D, Eugster W, Fukuda M, Gower T, Hinzman L, Huntley B, Jia GJ, Kasischke E, Melillo J, Romanovsky V, Shvidenko A, Vaganov E, Walker D. 2002. Environmental variation, vegetation distribution, carbon dynamics and water/energy exchange at high latitudes. J Veg Sci 13:301–14.CrossRefGoogle Scholar
  43. Muller SV, Racoviteanu AE, Walker DA. 1999. Landsat MSS-derived land-cover map of northern Alaska: extrapolation methods and a comparison with photo-interpreted and AVHRR-derived maps. Int J Remote Sens 20:2921–46.CrossRefGoogle Scholar
  44. Nelson FE, Shiklomanov NI, Mueller GR, Hinkel KM, Walker DA, Bockheim JG. 1997. Estimating active-layer thickness over a large region: Kuparuk River Basin, Alaska, USA. Arctic Alpine Res 29:367–78.CrossRefGoogle Scholar
  45. Notaro M, Vavrus S, Liu ZY. 2007. Global vegetation and climate change due to future increases in CO2 as projected by a fully coupled model with dynamic vegetation. J Clim 20:70–90.CrossRefGoogle Scholar
  46. Oechel WC, Vourlitis GL, Verfaillie J, Crawford T, Brooks S, Dumas E, Hope A, Stow D, Boynton B, Nosov V, Zulueta R. 2000. A scaling approach for quantifying the net CO2 flux of the Kuparuk River Basin, Alaska. Global Change Biol 6:160–73.CrossRefGoogle Scholar
  47. Olthof I, Pouliot D, Latifovic R, Chen WJ. 2008. Recent (1986–2006) Vegetation-specific NDVI trends in Northern Canada from satellite data. Arctic 61:381–94.Google Scholar
  48. Parsons AN, Welker JM, Wookey PA, Press MC, Callaghan TV, Lee JA. 1994. Growth responses of 4 Sub-Arctic dwarf shrubs to simulated environmental change. J Ecol 82:307–18.CrossRefGoogle Scholar
  49. Payette S, Fortin MJ, Gamache I. 2001. The subarctic forest-tundra: the structure of a biome in a changing climate. Bioscience 51:709–18.Google Scholar
  50. PCI Geomatics. 2001. OrthoEngine Reference Manual. Version 8.2. Richmond Hill, ON: PCI Geomatics.Google Scholar
  51. Pelletier BR. n.d. Environmental Atlas of the Beaufort Coastlands. Geological Survey of Canada. Accessed December 2009.
  52. Pomeroy JW, Marsh P, Gray DM. 1997. Application of a distributed blowing snow model to the Arctic. Hydrol Process 11:1451–64.CrossRefGoogle Scholar
  53. Pomeroy JW, Marsh P, Jones HG, Davies TD. 1995. Spatial distribution of snow chemical load at the tundra-taiga transition. In: Tonnessen KA, Williams MW, Tranter M, Eds. Biogeochemistry of seasonally snow-covered catchments. International Association of Hydrological Sciences No. 228. Wallingford: IAHS Press. p 191–203.Google Scholar
  54. R Development Core Team. 2006. R: a language and environment for statistical computing, reference index, version 2.6.2. R Foundation for Statistical Computing., Vienna, Austria.
  55. Reeburgh WS, King JY, Regli SK, Kling GW, Auerbach NA, Walker DA. 1998. A CH4 emission estimate for the Kuparuk River basin, Alaska. J Geophys Res Atmos 103:29005–13.CrossRefGoogle Scholar
  56. Richards JA, Jia X. 2006. Remote sensing digital image analysis: an introduction. Heidelberg: Springer.Google Scholar
  57. Ritchie JC. 1984. Past and present vegetation of the far Northwest of Canada. Toronto, ON: University of Toronto Press.Google Scholar
  58. Schimel JP, Bilbrough C, Welker JA. 2004. Increased snow depth affects microbial activity and nitrogen mineralization in two Arctic tundra communities. Soil Biol Biochem 36:217–27.CrossRefGoogle Scholar
  59. Schneider J, Grosse G, Wagner D. 2009. Land cover classification of tundra environments in the Arctic Lena Delta based on Landsat 7 ETM+ data and its application for upscaling of methane emissions. Remote Sens Environ 113:380–91.CrossRefGoogle Scholar
  60. Silapaswan CS, Verbyla DL, McGuire AD. 2001. Land cover change on the Seward Peninsula: the use of remote sensing to evaluate the potential influences of climate warming on historical vegetation dynamics. Can J Remote Sens 27:542–54.Google Scholar
  61. Sirois L. 1992. The transition between boreal forest and tundra. In: Shugart HH, Leemans R, Bonan GB, Eds. A systems analysis of the global boreal forest. Cambridge University Press: Cambridge, p 197–215Google Scholar
  62. Smith A, Strand E, Steele C, Hann D, Garrity S, Falkowski M, Evans J. 2008. Production of vegetation spatial-structure maps by per-object analysis of juniper encroachment in multitemporal aerial photographs. Can J Remote Sens 34:S268–85.Google Scholar
  63. Soil Landscapes of Canada Working Group. 2007. Soil Landscapes of Canada v3.1.1 (digital map and database at 1:1 million scale). Ottawa, ON: Agriculture and Agri-Food Canada.Google Scholar
  64. Stafford JM, Wendler G, Curtis J. 2000. Temperature and precipitation of Alaska: 50 year trend analysis. Theor Appl Climatol 67:33–44.CrossRefGoogle Scholar
  65. Stow DA, Hope A, McGuire D, Verbyla D, Gamon J, Huemmrich F, Houston S, Racine C, Sturm M, Tape K, Hinzman L, Yoshikawa K, Tweedie C, Noyle B, Silapaswan C, Douglas D, Griffith B, Jia G, Epstein H, Walker D, Daeschner S, Petersen A, Zhou LM, Myneni R. 2004. Remote sensing of vegetation and land-cover change in Arctic tundra ecosystems. Remote Sens Environ 89:281–308.CrossRefGoogle Scholar
  66. Sturm M, McFadden JP, Liston GE, Chapin FS, Racine CH, Holmgren J. 2001a. Snow-shrub interactions in Arctic tundra: a hypothesis with climatic implications. J Clim 14:336–44.CrossRefGoogle Scholar
  67. Sturm M, Racine C, Tape K. 2001b. Climate change—increasing shrub abundance in the Arctic. Nature 411:546–7.CrossRefPubMedGoogle Scholar
  68. Sturm M, Schimel J, Michaelson G, Welker JM, Oberbauer SF, Liston GE, Fahnestock J, Romanovsky VE. 2005. Winter biological processes could help convert Arctic tundra to shrub land. Bioscience 55:17–26.CrossRefGoogle Scholar
  69. Tape K, Sturm M, Racine C. 2006. The evidence for shrub expansion in Northern Alaska and the Pan-Arctic. Global Change Biol 12:686–702.CrossRefGoogle Scholar
  70. Thompson C, Beringer J, Chapin FS, McGuire AD. 2004. Structural complexity and land-surface energy exchange along a gradient from Arctic tundra to boreal forest. J Veg Sci 15:397–406.CrossRefGoogle Scholar
  71. Walker DA. 2000. Hierarchical subdivision of Arctic tundra based on vegetation response to climate, parent material and topography. Global Change Biol 6:19–34.CrossRefGoogle Scholar
  72. Walker DA, Gould WA, Maier HA, Raynolds MK. 2002. The circumpolar Arctic vegetation map: AVHRR-derived base maps, environmental controls, and integrated mapping procedures. Int J Remote Sens 23:4551–70.CrossRefGoogle Scholar
  73. Walker MD, Wahren CH, Hollister RD, Henry GHR, Ahlquist LE, Alatalo JM, Bret-Harte MS, Calef MP, Callaghan TV, Carroll AB, Epstein HE, Jonsdottir IS, Klein JA, Magnusson B, Molau U, Oberbauer SF, Rewa SP, Robinson CH, Shaver GR, Suding KN, Thompson CC, Tolvanen A, Totland O, Turner PL, Tweedie CE, Webber PJ, Wookey PA. 2006. Plant community responses to experimental warming across the tundra biome. Proc Natl Acad Sci USA 103:1342–6.CrossRefPubMedGoogle Scholar
  74. Walker MD, Walker DA, Auerbach NA. 1994. Plant communities of a tussock tundra landscape in the Brooks range foothills, Alaska. J Veg Sci 5:843–66.CrossRefGoogle Scholar

Copyright information

© Springer Science+Business Media, LLC 2010

Authors and Affiliations

  • Trevor C. Lantz
    • 1
  • Sarah E. Gergel
    • 2
  • Steven V. Kokelj
    • 3
  1. 1.School of Environmental StudiesUniversity of VictoriaVictoriaCanada
  2. 2.Department of Forest Science, Centre for Applied Conservation ResearchUniversity of British ColumbiaVancouverCanada
  3. 3.Renewable Resources and Environment, Indian and Northern Affairs, CanadaYellowknifeCanada

Personalised recommendations