Carbon in ecosystems of Central : the effect of forest invasion to tundra Prokushkin A.S., Klimchenko A.V., Korets M.A., Rubtsov A.V., Kirdyanov A.V., Shashkin A.V., Prokushkina M.P., Zrazhevskaya G.K., Shibistova O.B., Guggenberger G. and Richter A.

V.N. Sukachev Institute of Forest SB RAS, Akademgorodok 50/28, Krasnoyarsk, [email protected]

ENVIROMIS-2012, June 27, Irkutsk 1 How forest vegetation freezes the soil

ENVIROMIS-2012, June 27, Irkutsk 2 ESF JRP: Long-term Carbon Storage in Cryoturbated Arctic Soils Cryocarb • The overarching goal of CryoCARB is to advance organic carbon estimates for cryoturbated soils, focusing on the Eurasian Arctic and to understand the vulnerability of these carbon stocks in a future climate. • The constraints to our understanding of carbon dynamics in cryogenic soils are currently manifold:

First, due to cryoturbation, organic matter is unevenly distributed within the soil, making SOC estimation very difficult. There is evidence that the North American arctic carbon stock is bigger than previously thought, also because of underestimation of carbon stored in distorted, broken and warped horizons [4]. Second, most studies dealing with SOC in arctic soils fail to account for carbon stored in the upper permafrost, although the latter is directly under threat in a rapidly warming Arctic [1]. Thawing of the upper permafrost will also mobilize old, geogenic C [8], which is rarely addressed. Third, the mechanisms of carbon stabilization are largely unknown thus hampering the prediction of [3,5] climate-CO2 feedbacks . Knowledge of the chemical composition of organic matter and the processes on how carbon is stabilized is necessary to predict the magnitude and the time-scale at which SOC will get remobilized from thawing permafrost under climate change [9]. 3 Cryosols are reservoir of 747 Gt C in the upper 3 m, excluding peatlands and carbon in deep loess sediment

4 Problem Accelerated decomposition and release of ancient soil carbon in extensive Tundra biome (12 million km2) upon global warming may cause significant increase of net C fluxes to atmosphere in Northern Hemisphere McGuire et al. (2010) Shaver et al. (2006) J. of Ecology Corradi et al. (2005) Global Change Biol. Etc.

Climatic response of permafrost soils will vary significantly with (i) location (e.g. tundra subzone), (ii) SOM quality, (iii) involved stabilization mechanisms and (iv) invasion of woody vegetation. Key goal of “Cryocarb” Project is to obtain the explicit information on factors from i to iii, which are specifically important with regard to cryoturbation processes Gundelwein et al. (2007) Eur. J. SoilSci. Associated project (RFBR #10-04-01003) “Stabilization of organic matter in cryoturbated soils of Siberia” aimed to estimate the role of forest invasion to tundra in carbon budget 5 Examples of Cryoturbation processes and OC distribution within the soil

6 Research objectives: go into forest- tundra ecotone and…

• Determine OC storage in vegetation and soil • Assess ecosystem-scale variability in OC stocks between tundra, sparse and closed forests • Study transformation of soil organic matter by isotopic and biomarker fingerprints

7 Study sites

• Taymyr (Ary-Mas) Ary-Mas MAT = -13oC - 3 transects Kyndyn

• (Kyndyn) MAT = -10oC - 1 transect Tembenchi • Putorana (Tembenchi) MAT = -9oC Tura MAT = -6oC - 2 transects Baykit

• Tura

sites - 3 transects Notundra • Baykit - survey is planned in near future 8 Table 1. Characteristics of altitudinal transects (upland landforms) within Central Siberia.

Soil properties Transect, Coordinates Altitude, MAAT, Vegetation Patterned stone number of m a.s.l. oC ground, % content, % plots Ary-Mas 72o30’ N southern n=11 102o30 E 20-90 -13.8 tundra-larch 0-35 0-10 forests Kyndyn 70o52’ N mountain n=4 102o56’E 70-370 -13.1 tundra-larch 0-40 5-25 forests Tembenchi 65o25’ N mountain n=25 97o35’ E 200-900 -10.8 tundra-larch 0-50 5-90 forests

9 Structure of presentation

• Some words about forest research in high latitudes of Northern Eurasia and Northern America

• Tree-line advances and retreats in past

• Present forests: tree generations and TRW (Ary-Mas case study)

• Vegetation biomass, soil organic carbon, soil temperatures and permafrost on altitudinal transects of Taimyr, Anabar and Putorana Plateaus

10 Current knowledge about forest-tundra terrains • Taimyr forest research history: Middendorf 1867, Tolmachev 1920s, Tyulina 1930s, Lovelius 1970s-80s, Naurzbaev 1990s-2000s

• Numerous dendroclimatic studies in Circum-arctic Eurasia (publications of McDonald, Briffa, Vaganov, Naurzbaev etc.)

• Forest invasion to the tundra: - Polar Ural (Shiyatov et al. numerous publications) - Taymyr Peninsula (e.g. Kharuk et al., 2004, Ranson et al., 2004) - Alaska (e.g. Suarez et al., 1999)

• Vegetation change (e.g. Sturm et al., 2001, Tchebakova et al., 2009 etc.)

• Effects of woody species invasion to tundra on soil C stock are controversial: - Positive (e.g. Steltzer 2004) - Negative (e.g. Wilmking et al. 2006) 11 Global temperatures for last 150,000 years

12 Taimyr tree-line advances and retreats: 50,000 years

Pleistocene Holocene

74 Каргинское время Голоцен Сартанское время Karginskoe inter-glacial Sartanskoe glacial 73

Ary-Mas

72 Present Larix tree-line Latitude Северная широта

71 NO fossil wood 0 2000 -8000 -6000 -4000 -2000 -52000 -50000 -48000 -46000 -44000 -42000 -40000 -38000 -36000 -34000 -32000 -30000 -28000 -26000 -24000 -22000 -20000 -18000 -16000 -14000 -12000 -10000 годы до нашей эры и годы нашей эры Year

• Dating based on Larix wood macrofossils distribution in Taimyr Peninsula during the last 50,000 years (Naurzbaev, Vaganov, 2000; Briffa et al., 2000, Naurzbaev et al., 2002, 2003 http://www.cru.uea.ac.uk/ 13 cru/people/briffa/qsr1999). Fossil wood

Fossil wood in eroded river bank of River – large peat deposit

Fossil wood on the lake bank in 3 km from Novaya River (ca 60 m a.s.l.) 14 Tree-line advances and retreats: Holocene optimum (10,000-3,500 years BP)

MacDonald G et al. Phil. Trans. R. Soc. B 2008; 363:2283-2299

• forest-tundra ecotone shifted ca. 300 km north 10,000 years BP and retreated ca. 3,500 years BP.

• NB: SOC older 3,500 years has been formed in forested terrain.

15 Northern Hemisphere (Mann et al. 1999), Arctic (Overpeck et al. 1997) and northern Eurasian (Briffa & Osborn 1999; Briffa 2000) summer surface-temperature trends over the past 1000 years (adapted from Overpeck et al. 1997; Briffa & Osborn 1999; Mann et al. ... Cit.: MacDonald G et al. Phil. Trans. R. Soc. B 2008; 363:2283-2299

40 3 35 2 30 1 25 20 • Tree establishment generally 15 coincides with temperature peaks Frequency 10 5 0 1690 2010 • Large frequency of trees 1530 1570 1610 1650 1730 1770 1810 1850 1890 1930 1970 established in 20th century Naurzbaev 2005

16 Approaches

• Stand - Measurements of DBH and H (tree census): - S = 200-10,000 m2 - >150 trees/plot - All seedlings

- Tree cores (n=15-25) and discs (n=5) for TRW measurements

- 5-10 seedlings for age and biomass measurements

• Biomass through allometric equation (Bondarev et al. 1970)

17 C stock estimate: sampling and measurements of ground vegetation and soil

• Shrubs (Salix spp., B. nana, D. fruticosa) - Cross transect (10×1 m) - Stem counting and measurement of total weight of samples (n=3-5) • Ground vegetation: 5-7 subplots (25×20 cm) - Dwarf shrubs (wet weight, subsamples to dry) - Grasses (wet weight, subsamples to dry) - Moss/lichen layer (wet weight, subsamples to dry) • Topsoil: 5-7 subplots - O horizon: (20×20 cm, wet weight, subsamples to dry) - Upper 0-5 cm: 5-7 subplots (1-3 cylinders) • Subsoil: 1 soil pit across mound and trough - Sampling at 0-5, 5-10, 10-20,… and upper 10 cm of permafrost (1-3 cylinders) - Soil temperature (every 5 cm) 18 Taimyr Peninsula: Ary-Mas site

• 3 altitudinal transects: - 2 north-facing slopes - 1 south-facing slope

• N-facing: - tree-line - 60 m a.s.l. - sparse forests - 40 m a.s.l. - “dense” forests – 10-20 m a.s.l.

• S-facing slope - species-line (krumholz) - 90 m a.s.l. - sparse forests – 60-20 m a.s.l.

Total number of plots: 11

19 Species-line (Krumholz): 90 m a.s.l. Plot views

Tree-line (biogroups): 60 m a.s.l.

Sparse forests (individual trees and biogroups): 40 m a.s.l.

“Dense” forests (individual trees): 10-20 m a.s.l.

20 Tree-line Sparse forest Sparse forest Closed forest Transect 1 Altitude, m a.s.l. 60 40 20 10 DBH, cm 5,69 8,73 10,77 9,55 H, m 5,72 7,47 8,51 7,90 * Logged in the past Tree density, ha-1 155 430* 400* 1860 "closinest" 0,04 0,11 0,14 0,35

Basal area, m2/ha 0,77 2,53 3,57 8,71 Wood stock, m3/ha 2,65 10,45 16,27 37,56 Wood stock, kg/m2 0,14 0,55 0,85 1,97 Transect 2 Altitude, m a.s.l. 60 40 20 DBH, cm 6,82 5,32 7,09 H, m 6,41 5,49 6,56

Northernaspect Tree density, ha-1 195 720 1950 "closinest" 0,03 0,08 0,33 Basal area, m2/ha 0,70 1,57 7,54 Wood stock, m3/ha 2,59 5,23 28,43 Wood stock, kg/m2 0,14 0,27 1,49

Transect 3 Altitude, m a.s.l. 60 40 20 DBH, cm 5,60 5,94 4,38 H, m 5,67 5,88 4,86 Tree density, ha-1 125 195 415 "closinest" 0,01 0,02 0,03 Basal area, m2/ha 0,30 0,53 0,61 3 21

Southernaspect Wood stock, m /ha 1,03 1,85 1,89 Wood stock, kg/m2 0,05 0,10 0,10 Tree growth

1.2 Uneven age structure: forests consist of 4-7 generations tree-line 1.0 sparse stand of larch trees (the oldest dated by1530) sparse stand Transect 1 closed forest No fire effect: no one tree with fire scare 0.8

0.6

Periods of larger TRW correspond to new larch mm width, ring Tree 0.4 generation establishment 0.2

th 0.0 20 century showed 4 periods with good growth of 1.21650 1680 1710 1740 1770 1800 1830 1860 1890 1920 1950 1980 2010 Year AD stands and new tree generation establishment tree-line 1.0 sparse stand closed forest Transect 2 Better radial growth of tree generations established after 0.8 1940’s 0.6

0.4 mm width, ring Treee

The latter generation (mid-1990’s) does not reach 1.3 m 0.2 height yet 0.0 2.51650 1680 1710 1740 1770 1800 1830 1860 1890 1920 1950 1980 2010 12 Year AD

2.0 10

1.5 8

1.0

6 mm width, ring Tree 0.5

Diameter (DBH), cm Diameter 4 0.0 1650 1680 1710 1740 1770 1800 1830 1860 1890 1920 1950 1980 2010 2 Year AD

0 22 1650 1680 1710 1740 1770 1800 1830 1860 1890 1920 1950 1980 2010 Year AD Ground vegetation

1,0 1,00 dwarf shrubs moss-lichen 0,90 grasses

0,8 grasses 0,80 moss-lichen 2 dwarf shrubs 0,70 /m kg , 0,6 0,60 ck o 0,50 St 0,4 0,40 0,30

0,2 0,20 0,10

0,0 0,00 AM11-1 AM11-2 AM11-3 AM11-4 AM11-1 AM11-2 AM11-3 AM11-4 Tree-line Sparse forests Dense forest

100%

90%

80%

70%

60% dwarf shrubs 50% grasses 40% moss-lichen 30%

20%

10% 0% 23 AM11-1 AM11-2 AM11-3 AM11-4 Carbon pools in ecosystems

30

25 Trees 20 shrubs 15 dwarf shrubs grasses 10 moss-lichen

Carbon stock, kgC/m2 5 O horison Mineral 0.5 m 0 60 m 40 m 20 m 10 m Altitude, m a.s.l.

100% 90% 80% 70% Mineral 0.5 m 60% O horison 50% moss-lichen 40% grasses 30% dwarf shrubs 20% 10% shrubs 0% Trees 24 Soil organic matter

25 2,0 -20 mineral 0.5 m O layer 0 2 20 1,6

2 20 15 1,2

Krummholz 40 Tree-line 10 0,8 Soil depth, cm depth, Soil

O layer, kgC/mO layer, cryoturbated? Sparse forest 60

Mineral layer (0,5 m), kgC/m Mineral (0,5 layer 5 0,4 80 Closed forest tree-line Sparse forest Dense forest

0 0,0 100 0 20 40 60 80 100 0 20 40 60 80 100

Altitude, m a.s.l. Ratio (LOI250:LOI550) %

• Invasion of forest has little effect on the C stock in 0.5 m layer of soil • Invasion of forest leads to the accumulation of C in O layer • Forest SOM is less thermoresistant: in short-term perspective to analyze biodegradability in incubation experiment 25 Forest invasion (moss and O layer development) affects soil temperature

0 0

20 Transect #1 20 Transect #2

40 40

60 60 Soil depth, cm depth, Soil Soil depth, cm depth, Soil

tree-line tree-line 80 80 sp a rse fo re st sp a rse fo re st closed forest closed forest 100 100 0 5 10 15 20 0 5 10 15 20 o Temperature, C Temperature, oC

26 …and permafrost depth

0

10

20

30

y = -53.633x + 97.767 40 R2 = 0.908 50

60

Permafrost depth, cm depth, Permafrost 70

80

90

100 0.0 0.5 1.0 1.5 O layer, kg/m2 27 Tundra, tree-line and forests in Anabar plateau

369 m a.s.l.

71 a.s.l.

28 Soil C stocks

б) 30

25 2 20

15 кгСм , / Запасы 10

5

0 0 100 200 300 400 29 Высота н.у.м., м

Soil Temperature

Температура почвы, оС 0 2 4 6 8 10 12 0

28 см 20 15 10 43 см 5 С о , 0 ы 40 в ч -5 55 см о п а -10

см , Глубина р ту а -15 р е 60 71 см п -20 м е Forest Т -25 АМ-1 Tundra -30 АМ-4 80 25.7.09 25.9.09 25.11.09 25.1.10 25.3.10 25.5.10 25.7.10 АМ-2 Дата АМ-3

100

30 Tree-line and forests in

350 m 500 m 700 m

800 m

900 m

31 Ecosystem C stocks

25 y = -0,0128x + 18,107 "Tembenchi" R? = 0,4754 2 /m C 20 g k , y it s n 15 e d n o rb a 10 c m te s y s 5 o c E

20

0 18

0 200 400 600 800 1000 16

14 Altitude, m a.s.l. larch 12 tall shrub

dw shrub

10 grass

moss-lichen

8 O layer

Mineral soil 6

4

2

0 900 800 700 600 500 300 200 300 500 600 N-facing slope, m a.s.l. Valley, m a.s.l. S-fasing slope, m a.s.l. 32 Soil Temperature

0 Forests at 300 m

20

Forests at 700 m 40

60 Soil depth, cm depth, Soil Tree-line at 900 m 80

100 0 2 4 6 8 10 12 Soil T, oC 33 Organic layer stock vs. active layer thickness 0

20

40

ALT, cm ALT, 60

80

100 0 2 4 6 8 10 34 O layer, kgC/m2 “Forest” effects

• Changed plant species composition in ground vegetation (i.e. mosses replace grasses) • Increased ground vegetation coverage (no or little frost boils); • Enhanced O layer thickness

Causes: - Canopy effect? - Snow accumulation? - Litterfall biochemistry? 35 Tundra soils: Carbon stock comparison within top 100 cm (modified after Gundelweinet al., 2007 Eur. J. Soil Sci.) Author(s) Region Number of Organic carbon profiles kg OC m-2 Tarnokai& Smith Canada 14 4 –63 (1992) Matsumura& Russia 7 11 –20 Yefremov(1995) Batjes(1996) Worldwide 5 16 –125 Ping et al. (1997, Alaska 42 10 –94 2002) Stolbovoi(2000, Russia <163 17 2002) Post (2006) Worldwide – 14 Gundelweinet al. Sibiria 10 31 (2007)

within top 50 cm (depth estimate limited by shallow forest soils) This study Central Siberia 7 4–16 Tundra (tree-line) This study Central Siberia 27 6-27 36 Forests CONCLUSIVE REMARKS:

1. Soil organic matter of present tundra ecosystems could be formed in forested terrain of past warm period in HOLOCENE;

2. Larch invasion to tundra and stand development patterns such as closed canopy, complete moss cover of ground surface and accumulation of O layer all induce the raise of permafrost and decrease of soil temperature, both resulting in conservation of C (including previously cryoturbated horizons) in frozen subsoil for “LONG” period of time. 3. Warming as predicted for 2oC (for 2060) may convert tundra and forest-tundra ecotone areas to northern Larix taiga, but still underlain by continuous permafrost. 37 Perspectives:

1. Carbon age, biomarker analysis, isotopic composition (C, N) of SOM and vegetation at latitudinal transect (Central Siberia: Ary-Mas … Baykit) and altitudinal transects at all 5 sites; 2. Biodegradability of SOM in incubation experiments; 3. Retrospective analysis of satellite data (NDVI) for 10 km belt near 102oE from 71 to 73oN to estimate “greening” of the area. 38 Acknowledgements

• RFBR and ESF for financial support • Special thanks to all people assisted with field works and lab analyses

39 Thank you for attention!

40