Organic Carbon Pools in Cryogenic Soils (Cryosols) of the Kolyma Lowland

Transcription

1 Organic Carbon Pools in Cryogenic Soils (Cryosols) of the Kolyma Lowland N.S. Mergelov Laboratory of Soil Geography and Evolution, Institute of Geography, RAS, Moscow Implemented through: 1. IPY Project #262, Response of Arctic and Subarctic soils in a changing Earth: dynamic and frontier studies, PI - S.V. Goryachkin 2. IPY Project #373, Carbon Pools In Permafrost Regions, PI - Peter Kuhry Photo by Heidi Kristenson

2 Location of investigation site Geographical coordinates (69 N, 161 E) Cherskiy

3 Climate according to climate station in Cherskiy (forest tundra subzone) Sharply continental - mean annual air temperature (-1)-(-13) C - June-August temperature 12 C - January temperature -35 C - precipitation low ~ 2 mm, 4% in summer - the duration of a frost-free season is about days

4 Investigation site: main types of landscapes (Ikonos image provided by University of Alaska, Fairbanks) The Kolyma River Watershed surfaces depositions of late Pleistocene edoma (loess-icy complex) Incorporated floodplain of Kolyma and Panteleikha rivers Apron of the Rodinka mountain covered by thin layer of loess-like sediments Maximum resolution 1mх1m 1 km

5 Basic types of ecosystems on edoma watersheds Quasi-climax larch open woodland (~ 2 years old) Dense larch forest ( years old) Алас Larch open woodland ( years old)

6 Old larch open woodland (~ 2 years old) Thermokarst depressions (alases) Fire area of 3 years old Fire area of 2 years old

7 Incorporated floodplain of Kolyma and Panteleikha rivers Polygonal bogs (low-center polygons) Laidas (flooded meadows) Calamagrostis meadows Ridges, river banks

8 Catena from edoma watershed to thermokarst valley Old larch Top of edoma watershed open woodland h=25м Middle part of watershed slope lichen-grassmoss associations moss-osier associations Lower part of edoma watershed Bottom of thermokarst valley

9 Top and middle part of slopes at edoma watersheds Haplic/Turbic Cryosols

10 Lower part of edoma watersheds slopes Endogleyi-Turbi-Histic Cryosols

11 Gleyi-Histic Cryosols Bottom of thermokarst valley draining edoma watersheds

12 Burn (age - 2 years) Burn (age ~ 3 years) Gelic Gleysols Gleyic Cryosols

13 Larch open woodland (age ~ years) Dense larch forest (age ~ ) Turbic Cryosols Haplic Cryosols

14 Soil cover of investigation site (129,2 sq.km) Actual scale 1 : 23 Visualization scale 1 : 7

15 Average active-layer depth in various soil combinations Average activelayer depth, cm no data Rivers, lakes Settlements Visualization scale 1 : 7

16 OC densities in the active-layer OC densities, kg/m^2 Visualization scale 1 : 7

17 Average OC density in the active-layer of soils of Kolyma Lowland s forest tundra is 15,1 kg/m^2 The total carbon storage in the region being investigated (129,2 sq.km) is 1,6 Mt. Some estimates of OC densities (кg/m^2 in 1 meter layer) Zone/Subzone Authors Kononova, 1976 Bohn, 1976 Hampicke, Bach, 198 Kobak, Kondrasheva, 1986 Tundra 42, , North-taiga (in Cryolithozone) _, 2,6 1,

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19 OC in min. hor. > OC in org. hor. Organic carbon pools in mineral and organic horizons OC density, kg/m^2 35, 3, 25, 2, 15, 1, 5,, various soil types OC storage in min. and organic hor. in % from total OC storage in the active-layer 1% 9% 8% 7% % 5% 4% 3% 2% 1% % OC density, kg/m^2 2, 15, Average OC storage for all investigated soils OC in min. hor. < OC in org. hor. OC density, kg/m^2 35, 3, 25, 2, 15, 1, 5,, various soil types 1% 9% 8% 7% % 5% 4% 3% 2% 1% % , 5,, 1 OC storage in: - organic horizons - mineral horizons

20 Processes controlling SOC distribution in mineral soil profiles Cryoturbation (Douglas&Tedrow, 1959; Tarnocai and Smith, 1992; Michaelson et al., 1996; Bockheim et al., 1998; Ping et al., 1998 Ignatenko, 1971; Gubin, 1998, 1999 and others) Cryogenic retinization (illuviation and retention of DOC at permafrost table) (Karavaeva, Targulian, 19, 1963; Teterina, 1964 and others) In situ root decomposition and humification (Karavaeva, 1963; Ignatenko, 1971, 1972; Vasilievskaia, 198 and others) Inheritance of OC from parent material (Kaplina, 1978; Gubin, 1998, 1999; Vasilievskaia, 198 and others)

21 Models of organic carbon distribution induced by different processes (in mineral soil!) C org content mineral surface,5 1 1,5 2 C org content,5 1 1,5 2 C org content,5 1 1,5 2 C org content,5 1 1, Depth 3 4 Depth 3 4 Depth 3 4 Depth PT Cryoturbation In situ root decomposition and humification Cryogenic retinization (illuviation and retention of DOC at permafrost table) Inheritance of OC from parent material

22 Types of organic carbon distribution (in mineral soil) OC, %, 2, 4, 6, 8, Accumulative (41,6% out of all profiles) Depth, cm, 2, 4,, 8, With maximum in middle part of profile (11,7%) OC, %, 2, 4, 6, 8,, 1, 12, 2, OC, % 4, With second maximum above permafrost table (APT) (46,7%) Depth,cm, 2, 4, 6, 8,, 2, 4,, 8, Depth, cm, 8, 1, 12, 1, 12,

23 Types of DOC distribution in soils of Kolyma lowland open forests (based on UV-photometry of water extracts from fresh soil samples ) Absorbance, %, 2, 4,, 8, 2 Accumulative (35,7%) Depth,cm 4 With maximum in middle part of profile (28,6%) 8 Absorbamce, %, 2, 4,, 8, 1 2 Absorbance, % 4 With second maximum APT (35,7%) Depth,cm, 2, 4,, 8, 2 4 Depth,cm

24 Occurrence of different organic carbon distribution types in cryohydromorphic gleyic and non-gleyic soils (Cryosols) Occurrence of certain profile type, % Accumulative With a second maximum above permafrost table With maximum in middle part of profile 1 - cryohydromorphic gleyic soils (number of profiles: 42) 2 - cryohydromorphic non-gleyic soils (number profiles: 18)

25 Occurrence of soils with different organic carbon distribution in tundra and open forests Occurrence of certain profile type, % Accumulative With a second maximum above permafrost table With maximum in middle part of profile 1 tundra (number of profiles: 49) 2 open forests (number of profiles: 11)

26 Occurrence of different organic carbon distribution types depending on types of organic horizons Number of profiles Accumulative With a second maximum above permafrost table With maximum in middle part of profile Organic horizons: 1 О; 2 О+Т; 3 О+А1; 4 А1; 5 absent (soils of spots)

27 Ratio of labile to inert organic matter in soils labile fractions inert fractions labile fractions inert fractions, 1, 2, 3, 4, labile fractions inert fractions Depth, cm Depth, cm Depth, cm with maximum in upper part with maximum in central part with maximum above permafrost table Value of labile to inert fractions ratio in loess-icy complex sediments (edoma) ~,2 (Zhigotskiy, 1982) Labile fractions: Iа fraction of fulvic acids, I fractions of humic and fulvic acids, II fraction of fulvic acids Inert fractions: II fraction of humic acids, III fractions of humic and fulvic acids, pyrophosphate non-extractable carbon

28 Hydrophilous and hydrophobous organic matter fractions in Gleyic Cryosol Fractions content, % Hydrophilous fractions hydrophilous Hydrophobous fractions Ah T hydrophilous 3 - hydrophobous 4 - hydrophobous peak numbers G Bg B Fractions content, % Hydrophilous Hydrophobous fractions fractions T3 58,61 17,35 9,59 14,44 Ah 66,22 1,71 6,53 12,58 3,96 B 52,39 6,96 4,15 2,7 1,34 5,46 Bg 38,26 17,5 13,6 31,64 G 55,61 1,4 5,86 28,13

29 Change of color in mineral horizons after heating (2 C) B1 Before heating B1 After heating Bg Bg

30 Distribution of roots biomass and SOC reserves Depth, cm Roots biomas, kg/m^ kg/m^ kg/m^ Roots biomass, kg/m^2; - SOC reserves, kg/m^2 3 kg/m^ kg/m kg/m kg/m

31 Models of organic carbon distribution induced by different processes (in mineral soil!) C org content mineral surface,5 1 1,5 2 C org content,5 1 1,5 2 C org content,5 1 1,5 2 C org content,5 1 1, Depth 3 4 Depth 3 4 Depth 3 4 Depth PT 7 Cryoturbation 7 In situ root decomposition and humification 7 Cryogenic retinization (illuviation and retention of DOC at permafrost table) 7 Inheritance of OC from parent material

32 Models of organic carbon distribution induced by different processes C org content mineral surface,5 1 1,5 2 C org content,5 1 1, Depth 3 4 Depth PT 7 Cryoturbation 7 Cryogenic retinization (illuviation and retention of DOC at permafrost table)

33 Dynamics of forest fires at the North-East of Kolyma Lowland Number of fires years

34 Sequence of postpyrogenic succession change Old larch open woodland Fire Low shrub grassy stage Larch open woodland Quasiclimax larch open woodland Dense larch forest

35 Soil properties alteration in dependence to fire age and/or type of postpyrogenic succession Active-layer depth, cm lg (t, years) , 2, 4,, 8, 1, 12, 14, 1, Level of profile disturbance by cryoturbations, % 25, 2, 15, 1, 5, 1 2 2, lg (t, years) consecutive postpyrogenic development of larch open forest; 2 - development through stage of dense larch forest Postpyrogenic stages of vegetation recovery Burn without arboreal vegetation Burn without arboreal vegetation Burn without arboreal vegetation Larch open woodland Dense larch forest Quasiclimax larch open woodland Time passed after the last fire, years

36 Soil properties alteration in dependence to fire age and/or type of postpyrogenic succession Soil moisture, % Percentage of morphological gleyic features in profile 4, 35, 3, 25, 2, 15, 1, , lg (t, years), lg (t,years) 1 - consecutive postpyrogenic development of larch open forest; 2 - development through stage of dense larch forest Postpyrogenic stages of vegetation recovery Burn without arboreal vegetation Burn without arboreal vegetation Burn without arboreal vegetation Larch open woodland Dense larch forest Quasiclimax larch open woodland Time passed after the last fire, years

37 Alteration of OC densities in organic and mineral horizons in dependence to fire age and/or type of postpyrogenic succession OC density, kg/m^2 16, 14, I 12, 2 1, 1 2 8, , 4, 2 2, 1 2, Organic horizons Mineral horizons Total OC density, kg/m^2 16, 14, II 12, 2 1, 1 2 8, 1 2 6, 3 2 4, 3 2 2, 3 1 2, Organic horizons Mineral horizons Total lg (t, years) lg (t, years) 1 - consecutive postpyrogenic development of larch open forest; 2 - development through stage of dense larch forest Postpyrogenic stages of vegetation recovery Burn without arboreal vegetation Burn without arboreal vegetation Burn without arboreal vegetation Larch open woodland Dense larch forest Quasiclimax larch open woodland Time passed after the last fire, years

38 Conclusion Contemporary soils of Kolyma Lowlands s forest tundra contain large amounts of OC. The important aspect of Kolyma carbon-rich Cryosols is the proportion between OC in mineral and organic horizons. Our data shows that in most cases OC storage in the mineral part of profile is higher than in organic horizons. In average more than % of the active-layer carbon pool is concentrated in mineral horizons. Each organic profile in mineral soil is formed by combination of several processes: a) cryoturbations; b) humus accumulation due to root fall decomposition in situ; c) migration and retention of water-soluble organic matter; d) inheritance of OC from parent material. Cryoturbations and migration of water-soluble organic matter play the major role. Fires are among major factors influencing vegetation and soil successions at open forests of the Kolyma Lowland. All loamy cryohydromorphic soils formed at watersheds on loess-icy complex sediments represent various stages of postpyrogenic development. Intensity and strength of fires determine the type of plant succession, active-layer thickness, intensity of cryoturbations, development of gleyic processes, soil carbon stock and therefore classification status of soils. The influence of fires on soil carbon pools has dual nature: on the first stages - expected dramatic reduction of carbon pools in organic horizons and less expressed in mineral horizons; on the later stages - postpyrogenic effect of organic matter accumulation on the mineral surface and OC enrichment of mineral horizons due to intense recovery processes in ecosystem.