Investigating Tundra and Taiga Biomes with Remote Sensing

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Investigating Tundra and Taiga Biomes with Remote
Sensing

• Jessica Robin
• SSAI/NASA/GSFC

Photo courtesy of M. K. Raynolds
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Outline of presentation

• Climate change and arctic vegetation
• Remote sensing research
• Field research by Martha Reynolds (UAF)
• Research with GLOBE data

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Arctic Temperatures (1966-1995)
Image courtesy of National Snow Ice Center
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2001 temperatures compared to 1950 to 1981
normal temperatures
Image courtesy of Goddard Institute of Space
Science
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Northern Greening (1981-1999)
Image courtesy of Liming Zhou, Boston University
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Arctic Climate Impact Assessment
Report put out in 2004 by the Arctic Council and
the International Arctic Science Committee (IASC)
International panel The summary report,
graphics and detailed scientific report can be
found on the web at http//www.acia.uaf.edu/
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Key Findings of the ACIA regarding vegetation

• Arctic vegetation zones are very likely to shift
  causing wide-ranging impacts.
• Treeline is expected to move northward and to
  higher elevations, with forest replacing a
  significant fraction of existing tundra, and
  tundra vegetation moving into polar deserts.
• More productive vegetation is likely to increase
  carbon uptake, although reduced reflectivity of
  the land is likely to outweigh this, causing
  further warming.
• Disturbances such as insect outbreaks and forest
  fires are very likely to increase in frequency,
  severity and duration, facilitating invasion by
  non-native species.
• Where suitable soils are present, agriculture
  will have the potential to expand northward due
  to a longer and warmer growing season.

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Remote Sensing Research
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Recent studies have shown increases in
satellite-sensed indices (NDVI) of circumpolar
tundra vegetation. NDVI of boreal forests
shows decreasing trends.
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The spring season has started earlier and max
NDVI has increased

• NDVI trends for the forested and tundra regions,
  broken down by six-year intervals.
• The forested areas show a recent decline in the
  maximum NDVI.
• Tundra regions have shown a continued increase in
  NDVI and a marked 10-day shift toward earlier
  onset of greening.
• There is no corresponding shift in the cessation
  of the greening period.

10 increase in NDVI
10-day spring shift in growing season length
Goetz et al. 2005. PNAS,102 13521-13525
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Changes in arctic shrubs
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Yukon Flats National Wildlife Refuge, Riordan et
al. 2006 JGR
Shrinking lakes due to warmer temperatures
leading to changes in permafrost and more
evaporation affects vegetation.
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• Satellite data show changes
• Greenhouse warming experiments show changes
• but very few studies have been able to document
  changes occurring to undisturbed tundra

Community changes in ITEX experiment after 6 years
Open-top chamber
Control
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Field Research
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Current research by Martha K. Raynolds
University of Alaska Fairbanks

• Trying to measure existing tundra vegetation
  conditions in enough detail and in enough places
  that future changes due to climate change can be
  measured.

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Greenland
Arctic tundra bioclimate subzones
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a mosses, liverworts and lichens, b forbs, c
prostrate dwarf-shrubs, d non-tussock
graminoids, e -hemiprostrate dwarf shrubs, f
erect dwarf shrubs, g low shrubs, h tussock
graminoids

• Plant physiognomy occurring in different Tundra
  Bioclimate Subzones
• A mosses, liverworts and lichens with some
  grasses and forbs
• B rushes and prostrate dwarf shrubs with
  mosses, liverworts and lichens
• C hemiprostrate and prostrate dwarf shrubs
  with bryophytes and lichens
• D sedges, erect and prostrated dwarf shrubs
  with bryophytes and lichens
• E tussock sedges, low and erect dwarf shrubs
  with bryophytes and lichens

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Landscapes of the Tundra Bioclimate Zone
Subzone A
A coldest E warmest
N
Subzone B
No shrubs Erect dwarf shrubs
Hummocks Mounds Tussocks
Subzone C
Subzone D
S
Subzone E
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Research with GLOBE Data
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Monitoring vegetation phenology with GLOBE Data

• Satellite data from the past two decades shows a
  corresponding increase in growing season in
  northern latitudes
• (Myneni, R.B., Keeling, C.D., Tucker, C.J.,
  Asrar, G., and Nemani, R.R., 1997, Increased
  plant growth in the northern high latitudes from
  1981 to 1991, Nature, 386698-702.)
• However, minimal on-ground observations of plant
  phenology exist to validate such satellite
  findings

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OBJECTIVES

• Analyze the efficacy of phenology monitoring
  using GLOBE and satellite derived vegetation
  indices from AVHRR and MODIS data
• Compare AVHRR and MODIS data

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GLOBE SCHOOLS 10 Schools Elementary-High
School Public, Charter, Private, Home Anchorage
area (3) Fairbanks area (7) Lat 61.17 64.85
N Lon 147.52-149.41 W
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FIELDMEASUREMENTS
Birch

• Students made observations measurements
  (2001-2004)
• budburst, green-up, leaf growth green down
• research focused on budburst and green-up
• Trees/Shrubs Betula, Populus, Salix
• (Viereck, Leslie, A. and Little, Elbert L. Jr.
  1972. Alaska Trees and Shrubs. Agriculture
  Handbook No. 410. Forest Service, USDA,
  Washington D.C)

Poplar
Willow
GLOBE Students, Alaska Photo courtesy of Cheryl
Pratt and Elena Sparrow, U of Alaska Fairbanks
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SATELLITE DATA AVHRR

• Advanced Very High Resolution Radiometer
• On board NOAAs POES (Polar Orbiting
  Environmental Satellites) since 1979
• Research includes NDVI data for Fairbanks and
  Anchorage regions from 2001 - 2004

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SATELLITE DATA MODIS

• Moderate Resolution Imaging Spectroradiometer
• On board Terra Earth Observing System (EOS)
• Terra satellite launched in 1999
• This research includes NDVI data for Fairbanks
  and Anchorage regions from 2001 - 2004

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Comparison of satellite data
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Conclusions

• Different processing and spectral characteristics
  restrict continuity between AVHRR and MODIS NDVI
  datasets
• NDVI has limitations in boreal regions due to
  snow, large extent of conifers, and clouds