TRANSFORMATION OF LARCH-DOMINATED TRANSFORMATION OF LARCH-DOMINATED FORESTS AND WOODLANDS INTO MIXED FORESTS AND WOODLANDS INTO MIXED

TAIGATAIGA

E. Levine1, H. Shugart Jr.2, J. Ranson1, N. Mölders3,

J. Shuman2, R. Knox1, G. Sun4, V. Kharuk5 1NASA’s GSFC, Biospheric Sciences Branch, Greenbelt, MD

2Dept. of Environmental Sciences, University of Virginia, Charlottesville, VA3University of Alaska, Fairbanks, Geophysical Institute, Fairbanks, AK

4Dept. of Geography, University of Maryland, College Park, MD5Sukachev Forest Institute, Krasnoyarsk, Russia

Northern Boreal forest/Taiga biomeNorthern Boreal forest/Taiga biome

Siberian Taiga One of the largest unaltered boreal forest areas in the

world making up 19- 20% of the world’s forest area Significant carbon sink estimated to store 74 Pg C and

249 Pg C in the vegetation and soil, respectively Long, severe winters (up to 6 Long, severe winters (up to 6

months with mean temperatures months with mean temperatures below freezing) and short summers below freezing) and short summers (50 to 100 frost-free days) (50 to 100 frost-free days) Annual temperature range: -54°C to Annual temperature range: -54°C to

21°C (-65°F to 70°F ) 21°C (-65°F to 70°F ) with occasional extremes 73°C to 32 (-with occasional extremes 73°C to 32 (-

100°F to 90°F )100°F to 90°F )

mean annual precipitation: 38 to 51 cm mean annual precipitation: 38 to 51 cm (15 to 20 in)(15 to 20 in)

Major soils of the study areaMajor soils of the study area (US Soil Taxonomy) (Cryosol Working Group, 2003)

Permafrost thickness (cm) in the Permafrost thickness (cm) in the study areastudy area

Siberian Larch Siberian Larch (Larix sibirica)(Larix sibirica) Deciduous needleleaf conifer native to Russia and

northern China that loses it foliage each fall Occupies 270 million ha of boreal forest Siberian larch prefers light and is tolerant of both

heat and frost, allowing it to grow on permafrost sites, where it is often found

R R U U S S S S I I

A

A

In Northern SiberiaIn Northern Siberia Average temperatures have risen 1 to 3°C (3 to

5°F) over the past 30 years, compared to the worldwide average increase of 0.6°C (1°F)

Noticeable changes over the past few decades include increases in winter and fall precipitation winter warming higher soil temperatures permafrost thawing fires insect outbreaks ground subsidence

warming of the soil profile warming of the soil profile increased depth of active layerincreased depth of active layer increased organic decompositionincreased organic decomposition release of COrelease of CO22 and methane and methane change in soil moisture storagechange in soil moisture storage increased evaporationincreased evaporation increased runoff increased runoff change in forest specieschange in forest species Increased wildfiresIncreased wildfires

Some possible effects of Some possible effects of permafrost thawingpermafrost thawing

AREA 1

AREA 2

AREA 3

ObjectivesObjectives Use coupled forest gap and soil process models to

understand their process level interaction under different scenarios

Identify the extent of the evergreen conifer invasion using a combination of well-calibrated satellite data and ground measurements

Use these tools to forecast trends of forest species biodiversity in the region

QuestionsQuestions Are historical areas of larch dominance in Siberia Are historical areas of larch dominance in Siberia

transforming into a zone of mixed taiga in areas of transforming into a zone of mixed taiga in areas of disturbance? disturbance?

Will the trees in this ecosystem begin to grow faster Will the trees in this ecosystem begin to grow faster and gradually extend their reach farther north into and gradually extend their reach farther north into the treeless tundra?the treeless tundra?

Will extensive changes in the larch dominated and Will extensive changes in the larch dominated and adjacent forests impact the carbon, energy, and adjacent forests impact the carbon, energy, and water cycles of Siberia?water cycles of Siberia?

Will hotter, drier conditions inhibiting growth and Will hotter, drier conditions inhibiting growth and leave the forest prone to invasive species and leave the forest prone to invasive species and wildfires?wildfires?

Ecological Forecasts•Projected species composition and structure

Areal impacts•Model results mapped to stratified landscapes

COMBINED MODELINGForest Attributes

•Remote Sensing•Maps•Field measurements

•(e.g. forest type and structure, disturbance history)

Soil Attributes•Maps•Field Measurements

•(e.g. soil texture, bulk density, and horizon depths, moss thickness)

Climate•Weather Station Data•Warming and precipitation scenarios

MODEL INITIALIZATION

RESULTS

Remote Sensing•Predicted pixel level attributes•height •biomass •species composition•LAI

Field Measurements•Detailed ground knowledge

VALIDATION

Forest Model(FAREAST)

•Species composition •Stand structure •Seed sources•Others

Soil Model(HSTVS)

•Soil moisture flux•Soil temperature flux •Snow and moss insulation •Depth of active layer thaw •Others

FAREAST: A Boreal Forest SimulatorFAREAST: A Boreal Forest Simulator

Growth:•Available Light•Soil Moisture•Site Quality•Growing-Degree Days•Depth of Thaw•Diameter•Age•Height Mortality:

•Stress•Fire•Insects•Age

Regeneration:•Available Light•Soil Moisture•Site Quality•Depth of Thaw•Seed Bed•Seed Availability•Sprouting•Layering

Yan, X. and Shugart, H.H. (2005) FAREAST: a forest gap model to simulate dynamics and patterns of eastern Eurasian forests. Journal of

Biogeography, 32:1641-1658.

Krankina O.N., Krankina O.N., et al.et al. 2005. 2005. Effects of climate, disturbance, and species on forest biomass Effects of climate, disturbance, and species on forest biomass across Russia. across Russia. Can. J.For.ResCan. J.For.Res. 35: 2281-2293. 35: 2281-2293

Hydro-Thermodynamic Soil-Hydro-Thermodynamic Soil-Vegetation Simulation (HTSVS)Vegetation Simulation (HTSVS) Mölders, N., U. Haferkorn, J. Döring, G. Kramm, 2003: Long-term numerical investigations on the water budget quantities predicted by the hydro-thermodynamic soil vegetation scheme (HTSVS) Meteorol. Atmos. Phys., 84, 115-135.

Multi-layer soil model including peat, moss, and lichen

Multi-layer snow model Includes simulations of

heat conduction and water diffusion soil freezing and thawing and cross

effects release and consumption of latent heat effects of frozen soil layers on vertical

fluxes of heat, moisture and water vapor flux

HSTVS ResultsHSTVS Results Soil temperatures will be predicted more

accurately if frozen soil physics are considered The soil model captures the observed seasonal

course of soil temperature well and moisture acceptably

The largest uncertainty in simulated soil temperature occurs around freezing

Results are sensitive to soil properties Time steps larger than 10 minutes no longer

captures the active layer effectively Soil properties below 1meter are important 20 layers and a depth of -30m provide better

results

Tura field station, SiberiaTura field station, Siberia