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Lesson3,biocomplexity patgrd20110227(small)
- 1. Lesson 3: Biocomplexity ofsmall patterned-ground features D.A. (Skip) Walker Alaska Geobotany Center, Institute of Arctic Biology, UAF
- 2. Overview of talk Introduction: • What is biocomplexity? • What are patterned-ground features? • Why is this an important topic? • Conceptual models of patterned ground formation. Overview of results from project components: • Climate and permafrost • Soils and biogeochemistry • Vegetation • Modeling • Education
- 4. Goal of theBiocomplexity of Patterned-Ground Project To better understand the complex linkages between frost heave, frost cracking, biogeochemical cycles, vegetation, disturbance, and climate across the full Arctic summer temperature gradient in order to better predict Arctic ecosystem responses to changing climate. Biocomplexity Grid at Green Cabin, Banks Island, Canada, 2003
- 5. Why focus on smallpatterned- ground ecosystems?
- 6. BECAUSE: • The processesinvolved in the formation of patterned- ground landscapes are not well understood. • The importance of patterned ground with respect to biogeochemical cycling, carbon sequestration and other ecosystem processes is poorly known. • They are an ideal natural system to to help predict the consequences of climate change of disturbed and undisturbed tundra across the full Arctic climate gradient.
- 7. Frost-heave Complexity Questions Selforganization – How do frost-heave features self-organize themselves? – How is vegetation involved in this process? Complex adaptive systems – How do frost-heave and associated ecosystems change along the arctic climate gradient? – How does the vegetation affect the microclimate, ground ice, disturbance, and soils of frost-heave features along the Arctic climate gradient? Scaling issues – What are the emergent properties of frost-heave systems at different scales? – How do frost-heave features affect trace gas fluxes, hydrological systems, and patterns of wildlife at large spatial scales?
- 8. Variety of frost-boiland earth hummock forms along the Arctic climate gradient • Subzone A and B: Mainly small polygons with vegetation concentrated in the cracks. • Subzone C: Larger polygons, and frost- boils ( nonsorted circles) with vegetation in the cracks and margins of circles and mostly barren frost boils. • Subzone D: Partially vegetated circles with well-vegetated inter-circle areas with thick moss mats. • Subzone E: Mainly small circles and earth hummocks thickly covered in vegetation.
- 9. Some forms caused by differential frost heave • Frost-heave non-sorted circles • Earth hummocks Non-sorted circles, Howe Island, AK, Subzone E. Earth hummock, Inuvik, NWT, Canada,, Northern Boreal Forest. Non-sorted circles, Franklin Bluffs, AK, Subzone D. Photos: D.A. Walker
- 10. Earth hummocks causedby differential frost heave Earth hummocks, Subzone B, Mould Bay Incipient earth hummocks in large non- sorted seasonal frost-crack polygons, Subzone C, Green Cabin Earth hummock, Subzone E, Happy Valley Earth hummocks, northern boreal forest, Inuvik, NWT
- 11. Complexities caused by slope, soil moisture and rocky soils • Stripes on slopes • Very large non-sorted circles in wet sites. • Sorted circles in rocky soils. Non-sorted stripes, Subzone C, Green Cabin. Large non-sorted circles in wet soils, Green Cabin. Sorted Circles at Mould Bay, Canada, Elevation Belt A. Photos: D.A. Walker
- 12. Contraction Cracking • Small non- sorted polygons (Washburn 1980). • Occur on most sandy to clayey soils in the High Arctic (Subzones A, B, C). Mould Bay, Prince Patrick Island, • Contraction cracks in a drained lake basin, Seasonal frost Elevation, Belt A. Prudhoe Bay, Alaska, Subzone D. cracking (Washburn 1980). • Can be confused with desiccation cracking. Green Cabin, Banks Island, Howe Island, northern Alaska, Bioclimate Subzone C. southern Bioclimate Subzone C. Photos: D.A. Walker
- 13. Modification of smallpolygons to form turf hummocks • Erosion and eolian deposition modify the basic forms resulting in turf hummocks (Broll and Tarnocai 2003). Turf hummocks on slopes with Dryas integrifolia and Cassiope tetragona,
- 14. In the HighArctic, small contraction-crack polygons are the dominant patterned-ground features. • Small non- sorted polygons (Washburn 1980). • Occur on soils of all textures in the High Arctic. Mould Bay, Prince Patrick I. • May be caused by either desiccation cracking or seasonal frost cracking (Washburn 1980). Isachsen, Ellef Ringnes I. Howe Island, northern Alaska Photos: D.A. Walker
- 15. Desiccation cracking vs.seasonal frost cracking Desiccation cracking: • Washburn (1980) and Tricart (1967) attributed most fine- scale (<1-m diameter polygons) to desiccation cracking. Seasonal frost Desiccation cracks. Desiccation cracks. cracking: Mould Bay. Dinosaur Provincial Park, Alberta. • Ubiquitous on most High Arctic surfaces. • All soil textures. • Deeper cracking. • Experiments and models are needed to determine conditions Green Cabin, small non-sorted polygons Green Cabin, polygon removed from soil.
- 16. Frost cracking occursat many scales Permafrost crack nonsorted polygons, Kupar;uk Small seasonal frost-crack non-sorted polygons, R., Alaska Green Cabin. Frost cracking within small polygons, Mould Bay. Frost cracking within Dryas hummock, Green Cabin.
- 17. Role of soiltexture Rocky soils: sorted circles and polygons, Sandy soils: no circles nor hummocks Mould Bay, Prince Patrick I. Atkasuk, AK Silty soils: sorted circles without earth hummocks Clayey soils: earth hummocks, Prudhoe Bay, AK Inuvik, NWT
- 18. Variety of formson different substrates Stoney substrates: Mould Bay, Prince Patrick I.
- 19. Variety of formson different substrates Saline sandy loam substrate: Howe Island, Alaska
- 20. Variety of formson different substrates Mesic loamy substrates: Southern Yamal Peninsula (above), Kurishka, Kolyma R. (right)
- 21. In general: • Circular forms are caused by differential heave resulting in circles and earth hummocks. • Polygonal forms are caused by cracking (thermal or desiccation): – Large polygons (thermal contraction cracking penetrates deep into the permafrost) – Small non-sorted polygons (contraction cracking confined to zone of seasonal thaw) • Both differential heave and cracking can occur at a variety of scales forming complex landscape patterns. • The forms can be modified by soil texture and a wide variety of processes including sorting (sorted forms), erosion and eolian deposition (turf hummocks, high- centered polygons), down-slope soil movement (stripes and lobes).
- 22. Project initially focusedon “frost boils” • Caused principally by differential frost heave (Peterson and Krantz 2003). • Also called: • Non-sorted circles (Washburn 1980) • ‘Frost medalllions’ (Russian term), • ‘Mud boil’ (Zoltai and Tarnocai 1981) • ‘Frost boi’ (van Everdingen 1998) • ‘Frost scar’ (Everett 1966) • ‘Spotted tundra’ (pyatnistye tundry, (Dostoyalov and Kudravstev 1967). Subzone C, Howe Island, AK. Photo; D.A. Walker
- 23. What are non-sortedcircles? Sorted circles = Frost boil: “a patterned ground form that is equidimensional in several directions with a dominantly circular outline which lacks a border of stones…” van Everdingen 1998 • Frost “boil” is a misnomer because no “boiling” is involved. • Closest term in Russian is Piyatnoe medalion - “frost medallion” • Moroznoe kepenie - frost churning due to needle-ice formation. • Pyatneestaya tundra: “spotted tundra” in Russian Nonsorted circles Figures from Washburn 1980
- 24. The non-sorted circlesystem Sparsely vegetated circle Vegetated inter-circle area Courtesy of C. Tarnocai
- 25. Central Questions • How do biological and physical processes interact to form small patterned ground ecosystems? • How do these systems change across the Arctic climate gradient? Howe Island, AK. Photo; D.A. Walker
- 26. Conceptual model ofthe non-sorted circle system Non-sorted Circle Inter-circle area Vegetation Vegetation Ice Ice Soil Lenses Soil Lenses The white arrows indicate interactions and feedbacks between elements (frost boils and inter frost boils), and black arrows between components of each element (ice lenses, soils, and vegetation).
- 27. Examination of frostheave features across the Arctic bioclimate gradient Sub- Mean Dominant plant zone July growth forms Arctic bioclimate subzones tempera- ture (˚C) A 2-3 Cushion forbs, mosses, lichens B 3-5 Prostrate dwarf shrubs C 5-7 Hemi-prostrate dwarf shrub, sedges D 7-9 Erect dwarf shrubs, sedges mosses A B E 9-12 Low shrubs, C tussock sedges, D mosses E From the Circumpolar Arctic Vegetation Map, 2003.
- 28. Dominant drivers ofpatterned-ground formation across the Arctic bioclimate gradient Non-sorted circles Inter-circle areas Cold climate (subzone A) Vegetation Vegetation Dominantly physical processes on both circles and inter-circle areas Ice Lenses Soil Ice Lenses Soil Moderate climate (subzone C) Vegetation Vegetation Dominantly physical processes on circles and biological processes in inter- circle areas Ice Lenses Soil Ice Lenses Soil Warm climate (subzone E) Vegetation Vegetation Dominantly biological processes on both circles and inter-circle areas Ice Lenses Soil Ice Lenses Soil
- 29. 2005 Expeditions and Timeline: Dalton Highway:2001-2002 2004 Green Cabin: 2003 Mould Bay: 2004 2003 Isachsen: 2005 Synthesis: 2006-2008 2001-02
- 30. Ken Borak air supportin the
- 31. Low point ofthe 6-year project Stuck in the mud!!
- 32. Field Camp atGreen Cabin, Banks Island
- 33. Project components • Climate and permafrost: Vladimir Romanovsky, Ronnie Daanen, Yuri Shur • Soils and biogeochemistry: Chien-Lu Ping, Gary Michaelson, Howie Epstein, Alexia Kelley • Vegetation: Skip Walker, Anja Kade, Patrick Kuss, Martha Raynolds, Corinne Vonlanthen • Modeling: Ronnie Daanen, Howie Epstein, Bill Krantz, Dmitri Nikolsky , Rorik Peterson, Vladimir Romanovsky • Education: Bill Gould, Grizelle Gonzalez • Coordination and management: Skip Walker
- 34. Climate and permafrost component Vlad Romanovsky
- 35. The ice-lens partof the nonsorted-circle system Ice lenses • Ice lenses drive frost heave. • Numerous closely spaced lenses form as the soil freezes downward from the surface. • The increased volume of the water causes heave. • Heave also is caused by formation of ice at the bottom of the active layer as the soil freezes upward. Frozen soil core from a frost boil Photo Julia Boike
- 36. These processes aredescribed in three models of differential frost heave (Peterson and Krantz 2003, Daanen et al. 2008, Nickolsky et al. 2008). Briefly: • Heat preferentially escapes from the surface at high points of 20 cm organic small irregularities in the surface. horizon • These high points self-organize into patterns controlled by mechanical properties of the soil (e.g., texture) and active layer thickness. Nonsorted • These high points are sites of increased heat and water flux, Inter- circle circle ice-lens development, and more heave. Water is pulled to the site of freezing by cryostatic suction. Lenticular voids in soil in summer created by ice lenses. Schematic of soil undergoing top-down freezing. Ice lenses exist in the frozen region and permafrost underlies the active layer.
- 37. Frost heave measurements • Differential heave is the greatest in subzone D, where centers are unvegetated but areas Soil Heave between features 30.0 are well- Centers of PG features 22.5 Between PG features vegetated. Heave (cm) 15.0 • Heave greatest in 7.5 northern Alaska on silty soils 0 n* y in k nd * Sa ffs on y * se ik Ba lle oc ab e la u gw uv or hs Va tD Bl C Is ld In dh ac ou in en py es e ow ea Is kl M re ap W an D H G H Fr
- 38.
- 39. Charles Tarnocai Chien-Lu Pingand Gary Michaelson
- 40. Complete characterizationof soils • Large soil pits across full patterned ground cycle. • Lots of student help.
- 41. Current Buried carbon in the Active intermediate layer of Layer permafrost table Intermediate Layer of Upper Permafrost Courtesy of Gary Michaelson
- 42. Sequestered carbon beneathfrost boils Carbon-rich horizon at base of non- sorted circle Movement of carbon from margin of circle to kg OC m-2 the base of the Active layer – 37 Permafrost – 19 circle via gravity Total 56
- 43. Carbon is concentratedin the cracks between small polygons. Nonsorted circles, Ostrov Belyy, Russia. After removal of top 10 cm of soil. Circles are situated in the centers of 60-90-cm diameter nonsorted polygons with cracks.
- 44. Movement of organicmaterial along thermal cracks to the base of the active layer. Photos: Left and center: Laborovaya, Russia; right: Mould Bay, Canada
- 45. Large amounts ofcarbon are sequestered at the top of the permafrost table in the intermediate layer. Major questions: Courtesy of Misha Kenevskiy & Yuri Shur How old is the carbon? How stable is the carbon? Is it susceptible to decomposition if the active layer becomes deeper?
- 46. Structure of activelayer and top permafrost layers beneath a nonsorted circle. 1 – Active layer (zone of annually thawed soil). 2 – Transient layer (frozen in some summers and thawed in). 3 – Intermediate layer). 4 – Original permafrost. Arrows denote hyphothsized movement of organic
- 47. Ice-rich intermediate layer in the upper permafrost
- 48. Needle-ice (Pipkrakes) Soil surfaceis lifted by ice crystals during diurnal freeze-thaw cycles. Photos: Outcalt 1971; Davies 2001
- 49. Needle-ice consequences Cottage-cheese soil Braya bartlettiana and root
- 50. Biotic soil crusts •Important component of nitrogen cycle on frost boils. Soil crust on dry center of frost boil
- 51. Marl and bioticsoil crusts on wet soils
- 52. Marl with interior liningof algae and fungal hyphae
- 53. Nitrogen Mineralization studies Howie Epstein Alexia Kelley
- 54. Biogeochemical cycling andcarbon sequestration within frost heave features Based on Ping et al. 2002
- 55. Spatial variation in soil properties across a non- Available Nitrogen (ug cm-3) sorted circle 6 5 3 2 Michaelson, G.J., Ping, C.L., 0 interboil rim >3cm <3cm Bare Epstein, H., et al. 2008. Soils and frost boil ecosystems across the Water Content (cm3 cm-3) 1.0 North American Arctic Transect. Journal of 0.5 Geophysical Research - 0 Biogeosciences. 113:1-11. interboil rim >3cm <3cm Bare Inter Rim >3cm <3cm Bare Ping, C.L., Michaelson, G.J., Boil Veg. Veg. Soil Kimble, J.M., et al. 2008. Cryogenesis and soil formation along a bioclimate gradient in
- 56.
- 57. The added rolesof vegetation Plant cover: • Insulates the surface decreasing the heat flux and summer soil temperatures. • stabilizes cryoturbation and limits needle-ice formation. • Promotes nitrogen and carbon inputs to the soil. Bill Steere collecting Bryum wrightii on a frost N, Matveyeva - Map and drawing of frost boil at Prudhoe Bay, July, 1971. boil vegeation on the Taimyr Peninsula, Russia.
- 58. Approach: Measurements alongthe NAAT Measurements • 21 Grids and maps • Active layer • Vegetation • Snow • Climate /permafrost • Met station • Soil temperatures • Frost heave • Soils • Characterization • Nitrogen mineralization • Decomposition • Remote sensing • NDVI • Biomass 10 x 10 m grid at Isachsen
- 59. North American ArcticTransect Arctic Bioclimate Subzones Sub- MJT SWI zone (˚C) (˚C mo) A <3 <6 B 3-5 6-9 C 5-7 9-12 D 7-9 12-2 0 Canada E 9-12 20-3 5 Dalton Highway (7 locations) Fores >12 >35 t
- 60. Subzone A: Subzone D: Satellite Bay, Canada - 1 Biocomplexity grids Deadhorse, Alaska - 1 Isachsen, Canada - 3 planned Franklin Bluffs, Alaska - 3 Subzone B: Sagwon MNT, Alaska- 2 Mould Bay, Canada - 2 Ambarchik, Russian - 1 Subzone C: Subzone E: Howe Island, Alaska - 1 Sagwon MAT, Alaska - 1 West Dock, Alaska - 1 Happy Valley, Alaska - 3 Green Cabin, Canada - 3 Kurishka, Russia - 1 TOTAL 20 + (3 planned) = 23 Happy Valley Grid
- 61. Vegetation mapping andanalysis of Martha Raynolds of active-layer/heave/vegetation relationships Anja Kade
- 62. Small landscape mapsalong climate gradient: 10 x 10 grids Maps of 10 x 10 m study areas (Raynolds et al. 2008, JGR). Raynolds, M.K., Walker, D.A., Munger, C.A., et al. 2008. A map analysis of patterned- ground along a North American Arctic Transect. Journal of Geophysical Research - Biogeosciences. 113:1-18
- 63. Trends in patterned-groundmorphology and vegetation on zonal sites across the Arctic bioclimate gradient
- 64. Subzone A Isachsen, EllefRingnes Island, mean July temperature = 3 ˚C, SWI = 4 ˚C mo
- 65. Subzone C Howe Island,Ak and Green Cabin, Banks Island, MJT, 8 ˚C, SWI = 16 ˚C mo
- 66. Subzone E Tuktuyaktuk, NWT,Happy Valley, AK, MJT = 12 ˚C, SWI = 30 ˚C mo
- 67. Classification of patterned-groundvegetation along Plant communities the NAAT Soil and site data • Used the Braun-Blanquet appraoch. • Low Arctic: Kade, A., Walker, D.A., and Raynolds, M.K., 2005, Plant communities and soils in cryoturbated tundra along a bioclimate gradient in the Low Arctic, Alaska: Phytocoenologia, v. 35, p. 761-820. • High Arctic: Vonlanthen, C.M., Walker, D.A., Raynolds, M.K., Kade, A., Kuss, H.P., Daniëls, F.J.A., and Matveyeva, N.V., 2008, Patterned- ground plant communities along a bioclimate gradient in the High Arctic, Canada: Phytocoenologia, v. 38, p. 23-63.
- 68. Plant community table(cover) Plant species and cover information for each plant community Classification according to Braun-Blanquet approach Kade et al. 2005, Plant communities and soils in cryoturbated tundra along a bioclimate gradient in the Low Arctic, Alaska. Phytocoenologia, 35: 761-820.
- 69. Frost-boil plant communities,soil and site information Plant communities Soil and site data Kade et al. 2005, Plant communities and soils in cryoturbated tundra
- 70. Patterned-ground features Intermediate Ordination of zonal patterned Between patterned-ground features ground vegetation: controlling environmental gradients • NMDS ordination. • Clear gradient of vegetation response to cryoturbation within each subzone and clear floristic separation between subzones. • But no clear overall controlling factors for the whole data set. • Floristic separation between Alaska and Canada portions of the gradient due to different floristic provinces, and substrate differences. Walker, D.A., Kuss, P., et al., 2011 (in revision), Vegetation and patterned-ground relationships along the Arctic bioclimate gradient
- 71. Biomass for eachrelevé was used to develop landscape-level biomass for each grid. Raynolds, M.K., Walker, D.A., Munger, C.A., Vonlanthen, C.M., and Kade, A.N.a., 2008, A map analysis of patterned-ground (Raynolds et al. 2008, JGR) along a North American Arctic Transect: Journal of Geophysical Research - Biogeosciences, v. 113, p. 1-18.
- 72. To examine theinsulative effect of vegetation: n-factor was determined for each vegetation type. Loggers: i-button data loggers 1. base of live vegetation 2. base of organic horizons 3. center of circle vascular plant canopy live moss mat dead organic matter Typical frost boil mineral soil Tundra Circle Tundra Kade, A., Romanovsky, V.E., and Walker, D.A., 2006, The N-factor of nonsorted circles along a climate gradient in Arctic Alaska: Permafrost and Periglacial Processes, v. 17, p. 279-289.
- 73. n-factors for patterned-ground n-factor: features along the NAAT –Ratio of the degree-day total at the soil surface to the degree-day total of the air. n = DDTsoil / DDTair – Summer n factor uses thawing- degree days. – Winter n factor uses freezing- degree days. High Arctic: Mineral soil temperature warmer than air temperature because of radiative warming of the soil surface. Low Arctic: Interboil mineral-soil temperatures are colder than air Walker, D.A., Kuss, P., et al., 2011 (in revision), Vegetation and temperatures because of patterned-ground relationships along the Arctic bioclimate gradient insulation of vegetation and in North America Applied Vegetation Science. organic soil. Winter: Soil temperatures much warmer than air temperature, particularly in Low Arctic because of snow insulation.
- 74. Experimental alteration ofvegetation canopy to examine effects of vegetation on active layer and frost heave Ph.D. project of Anja Kade Control Vegetation Removal Graminoid Transplants Moss Carpet Transplants Response Variables: Frost Heave, Thaw Depth, Soil Moisture, Soil Temperature
- 75. Effects of vegetationon summer and winter soil surface temperatures. Barren Mean Summer Temperature: Summer Vegetation removal: +1.5˚C (+22%) Control Moss addition: -2.8 ˚C (-42%) Mosses Winter Mean Winter Temperature: Mosses Control Vegetation removal: -0.9˚C (-6%) Moss addition: +1.3˚C (+7%) Mosses • The sedge treatment had a similar response as the barren treatment. Kade and Walker, 2008, Arctic, Alpine and Antarctic Research
- 76. Effects vegetation onthaw depth and heave Maximum Thaw Depth 90.0000 Thaw depth (cm) 67.5000 45.0000 Thaw: 22.5000 Vegetation removal: +5 cm (+6%) Moss addition: -11 cm (-14%) 0 Treatment Sedges Mosses Control Frost Heave 16.0 Frost Heave 12.0 Heave (cm) 8.0 Heave: 4.0 Vegetation removal: +3 cm (+24%) 0 Moss addition: -5 cm (-40%) Treatment Sedges Mosses Control Kade and Walker, 2008, Arctic, Alpine and Antarctic Research
- 77. Effect of naturalvegetation on thaw along the climate gradient Average August 2006 Thaw Depth for Patterened Ground-features and Between Features 90.0000 Centers of Pattern-ground features Between Pattern-ground features 67.5000 Thaw Depth (cm) 45.0000 22.5000 Subzone I Forest I E I D I C I B I A I 0 ik y c ic fs e nd in y en lle Ba di s uv id ab uf or hs la ci Va ac Bl In Is C ld dh -A ac on ou in en py e ea Is on ow kl -N M ap re D an gw H G H on Fr Sa gw Sa Each bar represents the mean of 5 vegetation plots at each location.
- 78. Soil moisture Vegetation and Snow/vegetation Pattern insulation and Environmental Climate/weather heave Variables Soil Physics Soil Chemistry TMHM DFH accurate heave pattern density Models WIT3D ARCVEG liquid water vegetation redistribution succession vegetation pattern succession Measured input and/or calibration data DFH: Differential Heave model TMHM: Thermo Mechanical Heave Model Simulated calibration and/or Input data WIT3D: 3D Water Ice Temperature model Feedback ARCVEG: Arctic Vegetation succession model
- 79. Differential frost heave(DFH) model of frost-heave feature formation (Peterson and Krantz 2003) • Heat preferentially escapes from the surface at high points of small irregularities in the surface. 20 cm organic • These high points self-organize into patterns controlled horizon by mechanical properties of the soil (e.g., texture) and active layer thickness. • These high points are sites of increased ice-lens development, and more heave. Nonsorted Inter- circle circle • Theoretically, non-sorted circles should be more closely spaced in shallowly thawed soils. Lenticular voids in soil created by ice lenses. Schematic of soil undergoing top-down freezing. Ice lenses exist in the frozen region and permafrost underlies the active layer.
- 80. Modeling Components ofthe Project • Differential Frost Heave (DFH) model (Peterson & Krantz): Describes the self-organization of non-sorted circles in the absence of vegetation. Models the process of differential frost heave and spacing of frost features using linear instability analysis. • Thermo-mechanical model (TMM) of frost heave (Nikolskiy et al.): Detailed simulation of heaving process within a non-sorted circle that includes mass, momentum and energy conservation laws for water, ice, and soil. Accounts for the observation that heave is considerably greater than can be accounted for by simply freezing the amount of the water in the soil. • WIT/ArcVeg (Daanen & Epstein): A 3-dimensional model of frost heave. Mainly a hydrology-heave model driven by temperature differentials and changes in vegetation patterns.
- 81. Vegetation Component (Epstein, Walker et al.) Linking modeling Mineralization Soil Soil Recruitment Organic Organic efforts Carbon Nitrogen Climate Plant Carbon/ Resorption Cryoturbation Nitrogen Plant-Available Nitrogen N2-fixation N loss Ice-lens Component Soil Component (Krantz, Romanovsky, et al.) (Ping, Epstein et al.)
- 82. Differential Frost-Heave (DFH)Model • The model successfully predicts order of magnitude heave and spacing of frost boils. • Other predictions Position of ground surface and Particle trajectories over include effect of soil freezing fronts several hundred years texture, air temperature, snow depth on magnitude of heave. Soil creep Time to stabilization
- 83. Non-linear heat Liquid water balance conduction equation + Equation Soil particles conservation equation Heat Flux Active Layer Ice Lenses (organic soil) Seasonal frost So chin lea il m g Active Layer ov (mineral soil) em en Water Flux t& Ice Lens Heave Permafrost Permafrost change over time Nicolsky, D.J., Romanovsky, V.E., Tipenko, G.S., Walker, D.A. 2008. Modeling biogeophysical interactions in nonsorted circles in the Low Arctic. Journal of Geophysical
- 84. The effect ofinsulation: Themo-mechanical model of frost heave vegetation interactions 0.18 Displacement of the ground surface • Each blue line corresponds to the 0.16 No additional insulation different depth of an 0.14 2cm additional insulation 0.12 layer over boil. 4cm Heave (m) 0.1 6cm • The insulation 0.08 simulates the effect of 10cm vegetation cover on 0.06 frost heave. 0.04 0.02 • Thicker vegetation layer causes better thermal 0 0 0.2 0.4 0.6 0.8 1 1.2 insulation and lowers Distance from the center of a frost boil, m cryogenic suction, hence the smaller frost heave of the ground.
- 85. ArcVeg Model (Epsteinet al. 2000) CRYOTURBATION C Mineralization Climate CRYOTURBATION Soil Soil Current PlantBiomass Organic Organic Plant Attributes Recruitment Nutrient Carbon Nitrogen Resorption Senescence/ Mortality Plant Carbon / Climate N Mineralization Nitrogen by CRYOTURBATION N Immobilization Functional Type Plant Uptake/ in Foliage, Roots Growth and Wood Plant-Available Nitrogen Climate Current Plant Biomass Plant Attributes N2-Fixation N loss • Simulates the interannual dynamics of tundra plant community composition and biomass. • Parameterized for up to 20 plant growth forms. • Based on nitrogen mass balance among pools of soil organic and inorganic nitrogen, and live plant nitrogen in live phytomass. • Changes in temperature drive changes in net N mineralization and the length of the growing season and thereby alter the community biomass and composition. • Climate and disturbance are stochastic forcing variables.
- 86. Modeling WIT-ArcVeg Random vegetation Year1 Organized vegetation Year >1000 http://snowy.arsc.alaska.edu/WIT3D/ Daanen, R.P., Misra, D., Epstein, H., et al. 2008. Simulating nonsorted circle development in arctic tundra ecosystems. Journal of Geophysical Research - Biogeosciences. 113:1-10.
- 87. 3-D Modeling ofpatterned-ground formation (R. Daanen, D. Misra, H. Epstein) WIT3D/ArcVeg Model in ARSC Discovery Lab. Photo: Ronnie Daanen
- 88. Modeling did notaddress issue of cracking. The formation of almost all nonsorted circles also involve cracking! We didn’t understand this until late in the project. Scale 2m Howe Island, AK Photo by Anja Kade
- 89. Small non-sorted polygons SmallNon- Scale sorted polygons 2m (35-50 cm) Howe Island, AK Photo by Anja Kade
- 90. Non-sorted circles Frost- heave non- sorted circles (90-200 cm) Scale 2m Howe Island, AK Photo by Anja Kade
- 91. Medium-size non-sorted polygons Medium non-sorted polygons (200-300 cm) Scale 2m Howe Island, AK Photo by Anja Kade
- 92. Components of landscape modifiedby both cracking and differential heave Non-sorted polygon 35 cm Non-sorted circle 90 cm Medium non- sorted polygon 200 cm Large and small seasonal frost-crack non-sorted polygons, Howe Island. Photo: Anja Kade Large non-sorted permafrost crack polygons (20-30 m diameter), Howe Island Photo: D.A. Walker
- 93. New tools forlooking at complexity of patterned ground Ground-base LIDAR units for detailed 3-D views of frost heave: Daanen et al. 2010. Has shown that the annual frost can exceed 25 cm! Frost cracking model: Zhang et al. (in progress): Has replicated horizontal cracking observed at the top of the permafrost table and could help explain development of intermediate layer.
- 94. Conceptual model frost boils and earth hummock formation in relationship to permafrost dynamics Only model that invokes the permafrost and cracking! Others operate entirely in the active layer. Shur, Y., Jorgenson, T., Kanevskiy, M., and Ping, C.-L., 2008, Formation of frost boils and earth hummocks, in Kane, D.I., and Hinkel, K.M., eds., Ninth Internaitonal Conference on Permaforst, Fairbanks, Institute of Northern Engineering, University of Alaska Fairbanks, p.
- 95. Quickbird imagery: Deadhorse BiocomplexitySite Vlad’s Deadhorse climate station Nonsorted circles covering much of the image. Sizes about 2-4 m diameter.
- 96. Education component ill Gould,Grizelle Gonzalez, and students of Arctic Field Ecology course
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- 98. Conclusions 1. Patterned-ground morphology on zonal sites changes in predictable ways with differences in climate, soil-moisture, soil-texture, and the structure of the vegetation. 2. Contrasts in the vegetation on and between patterned-ground features is best developed in Subzones C and D. These differences drive the movement of heat and water and the development of frost heave. 3. Strong thermal, hydrological, and chemical gradients help to maintain the position of these features in the same locality over long time periods. 4. Cryoturbation of organic material and aggrading permafrost tables act to sequester large amounts of carbon within the permafrost of these ecosystems. 5. Models have replicated the patterns related to frost heave (non-sorted circles and earth hummocks). Contraction cracking will require new models. 6. The presence of non-sorted circles strongly affect a wide variety of ecosystem properties (soil temperatures, active-layer depths, carbon storage, flux rates, biodiversity, successional pathways) and determine how these systems respond to disturbances including climate change.
- 99. Synthesis of biocomplexity project 9 Articles from the North America transect: Walker, D.A., Epstein, H.E., Romanovsky, V.E., Ping, C.L., Michaelson, G.J., Daanen, R.P., Shur, Y., Peterson, R.A., Krantz, W.B., Raynolds, M.K., Gould, W.A., Gonzalez, G., Nicolsky, D.J., Vonlanthen, C.M., Kade, A.N., Kuss, P., Kelley, A.M., Munger, C.A., Tarnocai, C.T., Matveyeva, N.V., and Daniëls, F.J.A., 2008, Arctic patterned- ground ecosystems: A synthesis of field studies and models along a North American Arctic Transect: Journal of Geophysical Research - Biogeosciences, v. 113, p. G03S01.
- 100. Děkuji! Photo courtesy ofMartha Raynolds
- 101. Děkuji! Funding and Support: NSFOffice of Polar Programs, Grant No. OPP-0120736 International Arctic Research Center VECO Polar Resources Aurora Institute Parks Canada Inuvialuit Corp. Institute of Arctic Biology, UAF Participants in the Project: Howard E. Epstein and Alexia Kelley (Department of Environmental Science, University of Virginia) William A. Gould and Grizelle Gonzalez (International Institute of Tropical Forestry, USDA Forest Service) William B. Krantz (Department of Chemical Engineering, University of Cincinnati) Rorik A. Peterson (Geophysical Institute and Department of Geology and Geophysics, University of Alaska Fairbanks) Chien-Lu Ping and Gary Michaelson (Palmer Research Center, University of Alaska Fairbanks, Palmer, AK) Skip Walker, Martha K. Raynolds, Hilmar Maier, Christine Martin, Anja N. Kade, Julie A. Knudson, Patrick Kuss, Corinne Munger, Erin Cushing, Ronnie Daanan, Ina Timling (Alaska Geobotany Center, Institute of Arctic Biology, University of Alaska Fairbanks) Vladimir E. Romanovsky, Dimitri Nikolsky, and Gennadiy Tipenko (Geophysical Institute and Department of Geology and Geophysics, University of Alaska Fairbanks) Yuri Shur (Civil and Environmental Engineering Department, University of Alaska Fairbanks) Charles Tarnocai (Agriculture and Agri-Food Canada, Ottawa, CA) Students of Bill Gould’s Arctic Field Ecology Course (University of Minnesota)
Editor's Notes
- #2 This talk focus on factors that affect small patterned-ground forms and their interactions across a bioclimate gradient in northern Alaska and the western Canadian Arctic. \nThis is a collaborative effort by team members of an NSF-funded biocomplextiy project. \n
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- #5 This project focuses on frost-boil ecosystems. \n\nThe goal of the project is to better understand the complex linkages between frost heave, biogeochemical cycles, vegetation, disturbance, and climate across the full Arctic summer temperature gradient in order to better predict Arctic ecosystem responses to changing climate and land use.\n
- #6 Why focus on small patterned-ground features?\nThe processes involved in the formation of patterned-ground landscapes are not well understood.\n\nThe importance of patterned ground with respect to biogeochemical cycling, carbon sequestration and other ecosystem processes is poorly known. \n\nThey are an ideal natural system to to help predict the consequences of climate change of disturbed and undisturbed tundra. \n
- #7 Why focus on small patterned-ground features?\nThe processes involved in the formation of patterned-ground landscapes are not well understood.\n\nThe importance of patterned ground with respect to biogeochemical cycling, carbon sequestration and other ecosystem processes is poorly known. \n\nThey are an ideal natural system to to help predict the consequences of climate change of disturbed and undisturbed tundra. \n
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- #10 In summary, differential heave can cause a variety of non-sorted circle and hummock forms depending on the climate, soils, and the intensity of the vegetation action.\n
- #11 We first noticed that frost boils inter-graded with large hummocks, which have been called earth hummocks by Tarnocai and Zoltai. \n\nPeterson and Krantz recognized that hummocks had a similar origin to frost boils. In fact, their model was originally made to describe hummock formation and not formation of non-sorted circles.\n\nTwo things appear to lead to hummock formation. The first is an organic vegetation mat, that prevents the disturbance of soil by frost action. \n\nThe second is the presence of clay-rich soils, that restrict the soil from collapsing back to its original state when ice-lenses melt during the summer. \n\nWe also found that earth hummocks can occur in from Subzone B to Subzone E, but that they are most common in the south, where they are the predominant surface form. And are common even in forested areas. \n
- #12 The surface forms are subject to modifications by gravity, soil moisture, and the presence of rocky soils, which are outside the scope of this talk.\nBut: \nStripes often form on slopes. There are also many other forms that are created by slope processes. \n\nVery large non-sorted circles can form in wet silty soils of subzones C and D. These often have a ring of peat or tussocks around the perimeter of the circle.\n\nSorted circles commonly form in rocky soils.\n
- #13 In the High Arctic (Subzones A, B, and C), most surfaces with fine-grained soils have small polygons that are the result of contraction cracking.\n\nThere is some debate regarding whether or not the majority of these are caused by desiccation cracking or by frost cracking that is confined to the active layer.\n
- #14 Modification of small polygons occurs on slopes where erosion and eolian deposition modify the basic polygon forms resulting in turf hummocks, which have been described by Broll and Tarnocai (2003).\nThese features often are associated with snow beds and distinctive plant communities that form a tight turf.\n
- #15 In the High Arctic (Subzones A, B, and C), most surfaces with fine-grained soils have small polygons that are the result of contraction cracking.\n\nThere is some debate regarding whether or not the majority of these are caused by desiccation cracking or by frost cracking that is confined to the active layer.\n
- #16 My impression from the literature is that the prevailing view is that most of these small polygons are the result of desiccation cracking.\n\nWashburn states in his 1980 book that most fiine-scale (<1-m diameter) polygons are the result of desiccation cracking.\n\nI think that this statement needs to be re-evaluated, through experiments and models to see just what conditions are necessary for the formation of small polygons.\n\nThese features are ubiquitous on most High Arctic surfaces, in all soil textures and all moisture regimes. And they seem to have deeper cracking than soils that have obvious desiccation cracking.\n\nAnother factor suggesting that seasonal frost cracking is the cause of most of these features, is the lack of such features in non-permafrost cold desert areas outside of the Arctic.\n\nIt seems that these features are possibly a result of both processes, but that frost cracking initiates the process of polygon formation and then other processes of erosion, desiccation, and repeated frost cracking modify the original features. \n
- #17 Contraction cracking occurs at several scales. \nIn the upper left, ice-wedge polygons up to 20 m across are the result of permafrost cracking at very cold temperatures.\n\nWe have been discussing much smaller features the result from cracking within the active layer. As in the upper right. \n\nWithin these features, even smaller polygons form such as in the lower left. \n\nCracking at similar scales can even occur within cushions of vegetation as in the lower right, Suggesting that within a certain range of scales, frost cracking may be fractal. \n
- #18 Soil texture also strongly influences the form of the patterned ground features.\n\n Sorted circles form in rocky soils.\n Earth hummocks in clayey soils.\n Sorted circles without hummocks in silty soils.\n And sandy soils are generally featureless without circles or hummocks.\n
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- #22 In general:\nCircular forms are caused by differential heave resulting in circles and earth hummocks.\n\nPolygonal forms are caused by cracking (thermal or desiccation):\nLarge polygons (thermal contraction cracking penetrates deep into the permafrost)\nSmall non-sorted polygons (contraction cracking confined to zone of seasonal thaw)\n\nBoth differential heave and cracking can occur at a variety of scales forming complex landscape patterns.\n\nThe forms can be modified by a wide variety of processes including sorting (sorted forms), erosion and eolian deposition (turf hummocks, high-centered polygons), down-slope soil movement (stripes and lobes).\n
- #23 The project initially focused on frost boils and spotted tundra. \n\nThese features are caused by differential frost heave. \n\nTheir formation has been modelled by Peterson and Krantz.\n\nThese features have a variety of names including: \nNon-sorted circles (Washburn 1980) \n &#x2018;Frost medalllions&#x2019; (Russian term), \n &#x2018;Mud boil&#x2019; (Zoltai and Tarnocai 1981) \n &#x2018;Frost scar&#x2019; (Everett 1966)\n &#x2018;Spotted tundra&#x2019; (pyatnistye tundry, (Dostoyalov and Kudravstev 1967).\n\nFor the remainder of this talk, I will refer to these features as nonsorted circles in conformance with the terminology of Washburn.\n
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- #26 The central questions are:. \nHow do biological and physical processes interact to form the patterned ground ecosystems?\n\nHow do these systems change across the Arctic climate gradient?\n\n\nTheir formation has been modelled by Peterson and Krantz.\n\nThese features have a variety of names including: \nNon-sorted circles (Washburn 1980) \n &#x2018;Frost medalllions&#x2019; (Russian term), \n &#x2018;Mud boil&#x2019; (Zoltai and Tarnocai 1981) \n &#x2018;Frost scar&#x2019; (Everett 1966)\n &#x2018;Spotted tundra&#x2019; (pyatnistye tundry, (Dostoyalov and Kudravstev 1967).\n\nFor the remainder of this talk, I will refer to these features as nonsorted circles in conformance with the terminology of Washburn.\n
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- #28 In our study, we are examining how these feature change across the arctic climate gradient in conjunction with climate and differences in vegetation. \n\nThis map shows the five bioclimate subzones of the Arctic vegetation Zone as described on the Circumpolar Arctic Vegetation Map.\n\nEach subzone is defined on the basis of a combination of climate and dominant vegetation. \n\nSubzone A is the coldest with a mean July temperature between 2 and 3 degrees C, and Subzone E is the warmest with mean July temperatures between 9 and 12 degrees C.\n
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- #31 Ken Borek Air Ltd. Was the company that rescued Dr. Jerri Nielsen from the South Pole a few years ago, when she realized she had breast cancer during the Antarctic winter.\n
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- #37 Differential frost heave occurs because soils do not uniformily freeze from top to bottom. Some areas form more ice-lenses than others.\n\nThe processes involved in differential frost heave have been described in a model by Peterson and Krantz (2003)\nVery briefly: Briefly: \n\n Heat preferentially escapes from the surface at high points of small irregularities in the surface. \n\n These high points self-organize into patterns controlled by mechanical properties of the soil (e.g., texture) and active layer thickness.\n\n These high points are sites of increased heat and water flux, ice-lens development, and more heave. Water is pulled to the site of freezing by cryostatic suction.\n
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- #58 Plant cover:\nInsulates the surface decreasing the heat flux and summer soil temperatures.\nstabilizes cryoturbation and limits needle-ice formation.\nPromotes nitrogen and carbon inputs to the soil.\n\nThe effect of vegetation on patterned ground morphology increases toward the south.\n
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- #76 The results showed as exoected, the vegetation strongly affects the soil surface temperatures.\nMean summer soil temperatures increased 1.5&#x2DA;C by vegetation removal and decreased 2.8&#x2DA;C by the addition of moss. \nMean winter soil temperatures decreased 0.9&#x2DA;C by vegetation removal and increased 1.3&#x2DA;C by the addition of moss.\nThe sedge treatment had a similar response as the barren treatment.\n
- #77 The differences in temperature had major effects on thaw depth and frost heave.\nThaw increased 5 cm with removal of vegetation and decreased 11 cm with addition of moss. \nHeave increased 3 cm with removal of vegetation and decreased 7 cm with addition of moss.\n
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- #80 The upper photo shows two soil plugs taken from a nonsorted circel (right) and an area in between two circles (left). \n\nThe lenticular voids that are evident in both soils are formed by ice lenses that form during the winter.\n\nThe model of Peterson and Krantz describes the formation of these lenses.\n\nVery briefly the model assumes homogeneous initial conditions in a silty soil that is prone to ice-lens formation.\n\nHeat preferentially escapes from the surface at high points of small irregularities in the surface. \n\n These high points self-organize into patterns controlled by mechanical properties of the soil (e.g., texture) and active layer thickness.\n\n These high points are sites of increased ice-lens development, and more heave. \n\n Theoretically, non-sorted circles should be more closely spaced in shallowly thawed soils.\n
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- #82 \nThe ArcVeg model will pass to the DFH model the total live phytomass by plant type and the total soil organic matter.&#xAF;&#xAF;\n
- #83 Quote from Bill Krantz: email 25 Aug 2003: \nThe DFH is very complex to model because of the vastly different scales of the various physical phenomena that must be incorporated into a viable model. The heat transfer occurs over the largest scale, namely the depth of the active layer, about one meter or so. However, the frost heave arises because the micron-scale pores in the particulate soil are preferentially wet by liquid water rather than by ice. Hence, freezing occurs on the micron scale in the pores, in involves a core of ice penetrating the center of a pore; the gap between the pore wall and this core of ice is occupied by unfrozen water. As the freezing soil becomes progressively colder, the ice core becomes thicker and the thin film of unfrozen water becomes thinner. When this film of unfrozen water thins to the scale of the long-range molecular dispersion forces (around 0.1 micron), the pressure tensor become anisotropic; that is the pressure in the direction parallel to the pore wall becomes less than the pressure perpendicular to the pore wall. This causes a suction (cryostatic suction) to be generated that pulls unfrozen water up from the water table thereby causing significantly more frost heave than can occur by just freezing the water in the soil. So far, we have three scales: the scale of the active layer (1 meter); the scale of the pore diameter in the soil (a few microns); and the scale for generating cryostatic suction (submicron). Yet there is another scale, namely that of differential frost heave: I.e., the diameter of the frost boils or hummocks. The scale is determined by a balance between nature wanting to make the corrugation or wavelength that characterizes the spacing between frost boils or hummocks as short as possible to permit more heat transfer and thereby more freezing, and the counter tendency of nature to avoid trying to bend a layer of frozen soil too much. Hence, what happens is compromise between nature trying to choose a short length scale to gie a lot surface area for hat transfer and long length scale to minimize the energy required to bend frozen soil. Believe it or not, the DFH model incorporates the physics occurring on all these scales! Now if that is not enough scales for you I suggest that you visit a fish market!\n\nI forgot to mention yet another scale that we incorporate into the DFH model. Although the heat transfer occurs over the longest length scale of the active layer depth, all the ice formation essentially occurs within the frozen fringe that is only a centimeter or so in thickness! One of the really difficult problems that we had to handle mathematically in the model was how to incorporate the physics of the frozen fringe. It is important to mention this centimeter length scale as well in your overview.\n\nOh, I forgot to mention yet another scale that we incorporate in the DFH model. Although the heat transfer occur over the longest length scale of the active layer depth, all the ice formation essentially occurs within the frozen fringe that is only a centimeter or so in thickness! One of the really difficult problems that we to handle mathematically in the model was how to incorporate the physics of the frozen fringe. \n
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- #86 ArcVeg simulates the interannual dynamics of tundra plant community composition and biomass based on nitrogen mass balance among pools of soil organic and inorganic nitrogen, and live plant nitrogen in live phytomass. \n Changes in temperature drive changes in net N mineralization and the length of the growing season and thereby alter the community biomass and composition. \n Climate and disturbance are stochastic forcing variables.\nThe DFH model will provide for ArcVeg the spatial frequencies of frost boil disturbances.\n Spatial and temporal dynamics of cryoturbation will influence the tundra system in ArcVeg through vegetation mortality and direct and indirect effects on soil nitrogen.\n
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- #89 In the High Arctic contraction cracking interacts with differential frost heave.\n\nThis remarkable photo was taken by Anja Kade at Howe Island, from an elevation of about 30 m above a field of nonsorted circles.\n\nThe scale bar shows the diameter of the features.\n
- #90 The smaller features are small non-sorted seasonal frost-crack polygons about 35 to 50 cm in diameter.\n
- #91 The white areas are nearly barren frost-heave non-sorted circles 90 to 200 cm in diameter.\n
- #92 Differential heave also appears to have aggregated the small non-sorted polygons into larger features that are 200 to 300 cm across.\n
- #93 This schematic summarizes the main components of the landscape. There are also much larger non-sorted ice-wedge polygons that enclose the entire field.\n\nThe aggregation of the small polygons into larger polygons by frost heave is fairly common, but vegetation often masks the smaller polygons particularly in more southern sites.\n
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