Land ecosystems cover nearly 30% of the Earth’s surface. The
land surface changes over days, seasons, decades, and longer.
Vegetation boundaries shift, cities grow, rain forests and farm
lands shrink, amounts of trace chemicals in the air increase
and decrease, rivers flood, forests burn, and volcanoes erupt.
Activities of the growing human population cause or influence
many of these changes.
Land ecosystems cover nearly 30% of the Earth’s surface. The
land surface changes over days, seasons, decades, and longer.
Vegetation boundaries shift, cities grow, rain forests and farm
lands shrink, amounts of trace chemicals in the air increase
and decrease, rivers flood, forests burn, and volcanoes erupt.
Activities of the growing human population cause or influence
many of these changes.
Space provides an excellent vantage point from which to
observe and record land surface changes, especially at a global
scale. NASA has embarked on an ambitious program called the
Earth Science Enterprise to measure the effects of changes on
our planet and to understand the roles that human activities
play in them. A suite of Earth-observing satellites looks at
different aspects of the land and builds a global picture of
change, one location at a time.
Space provides an excellent vantage point from which to
observe and record land surface changes, especially at a global
scale. NASA has embarked on an ambitious program called the
Earth Science Enterprise to measure the effects of changes on
our planet and to understand the roles that human activities
play in them. A suite of Earth-observing satellites looks at
different aspects of the land and builds a global picture of
change, one location at a time.
The Moderate Resolution Imaging Spectroradiometer (MODIS) Enhanced Vegetation Index (EVI) gives a detailed look at global vegetation patterns on a weekly basis. This image is an EVI image from early October 2000 that shows global vegetation distributions. Vegetation is denser near the equator, but is beginning to fade in the northern latitudes as they move into fall. Vegetation indices are useful for a wide range of scientific and environmental applications, including monitoring changes in the extent of deserts or wetlands, determining where
water stress may be causing habitat loss, and tracking changes in the length of growing seasons.
Image credit: MODIS Land Team/Vegetation Indices, Alfredo Huete, Principal Investigator; Kamel Didan
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Looking at Ecosystems and Vegetation
Looking at Ecosystems and Vegetation
Enhanced VegetationIndex
This image is an example of a MODIS land cover map. This map contains 17 different land cover types,
differentiating among eleven natural vegetation types such as deciduous and evergreen forests, savannas,
grasslands, and shrublands. High-quality land cover maps greatly aid scientists and policy makers involved in
a wide range of activities from natural resource management, such as land use and resource exploitation, to
research and global monitoring objectives.
Image credit: MODIS Land Cover Product, Alan Strahler, Principal Investigator; Mark Friedl and John Hodges, Boston University
Looking at Ecosystems and Vegetation
Looking at Ecosystems and Vegetation
0 Water1 Evergreen Needleleaf Forest2 Evergreen Broadleaf Forest3 Deciduous Needleleaf Forest4 Deciduous Broadleaf Forest5 Mixed Forests6 Closed Shrublands7 Open Shrublands8 Woody Savannas9 Savannas10 Grasslands11 Permanent Wetlands12 Croplands13 Urban and Built-Up14 Cropland/Natural Vegetation Mosaic15 Snow and Ice16 Barren or Sparsely Vegetated
Rapid change occurs as Mt. Etna erupts in
this Advanced Spaceborne Thermal
Emission and Reflection Radiometer
(ASTER) image taken on Sunday, July 29,
2001. Lava flows appear dark purple and
red and yellow indicate areas of highest
temperatures. Bluish smoke drifts across
the scene, and white clouds of volcanic
steam make shadows on the changing land.
Image credit: NASA/GSFC, METI/ERSDAC/JAROS, and U.S./Japan ASTER Science Team
Mount Etna EruptsMount Etna Erupts
Trailblazing firefighters and land
managers now use NASA satellite data
to combat wildfires. This image of the
southeastern coast of Australia on
January 2, 2002, from MODIS onboard
the Terra satellite, shows thick plumes
of grayish smoke streaming eastward
from more than a dozen active fires.
Fires encircle the city of Sydney,
which stands out in tan against the
surrounding green vegetation.
Image credit: Jacques Descloitres, MODIS Land Rapid Response Team at NASA/GSFC
Fighting Fires with Satellite Imagery
Fighting Fires with Satellite Imagery
In a collaboration between NASA, the
University of Maryland, and the U.S.
Department of Agriculture’s Forest
Service, firefighters receive maps and
satellite images of current active fires,
and use them for strategic planning.
After the fire is controlled, land
managers use the satellite images and
maps for post-fire rehabilitation and
protection of water quality.
This photograph was taken on August
6, 2000 in the Bitterroot National
Forest, Montana, when the forest was
ravaged by wildfires.
Image credit: John McColgan, Fire Behavior Analyst, Alaska Forest Service
Fighting Fires with Satellite Imagery
Fighting Fires with Satellite Imagery
A Landsat image (above, left) taken in 1972 and an ASTER image (above, right) taken in 2000 of Riyadh, Saudi Arabia dramatize evidence of an increasing human population. Population increases around the world have caused all sorts of problems, such as air pollution, traffic jams, overextended water resources, overfilled garbage dumps, and the destruction of natural wildlife habitats. Landsat and ASTER images provide important long-term records of urban growth, and can help us make decisions about the most effective use of space and resources for the future.
Landsat image credit: U.S. Geological Survey EROS Data Center and Landsat 7 Science Team
ASTER image credit: NASA/GSFC, METI/ERSDAC/JAROS, U.S./Japan ASTER Science Team
A City in the DesertA City in the Desert
1972 2000
The images on this and the following
two slides are of the Chesapeake Bay
region and Baltimore, Maryland (U.S.)
They showcase the different capabilities
of instruments on Earth-observing
satellites for viewing the land at
different light wavelengths and degrees
of detail.
This true-color MODIS image provides a
regional view of the area at a low 415
meters (about 1361 feet) resolution,
with Baltimore appearing as a white to
light gray area along the northwest edge
of the Chesapeake Bay.
MODIS image credit: Jacques Descloitres, MODIS Land Science Team
Views of the Chesapeake BayViews of the Chesapeake Bay
This Landsat 7 true color view of
Baltimore (Image 2) at 30 meters
(98.4 feet) provides further detail of
the region. Landsat 7 image credit: U.S. Geological Survey EROS Data Center and Landsat 7 Science Team
Views of the Chesapeake BayViews of the Chesapeake Bay
This ASTER image (Image 3) at 15
meters (49.2 feet) combines near-
infrared, red, and green light to create
a false-color image that depicts
vegetation as red, water as blue, and
urban areas as gray.
ASTER image credit: U.S./Japan ASTER Science Team
Views of the Chesapeake BayViews of the Chesapeake Bay
Southern California’s dramatic topography
plays a critical role in its climate,
hydrology, ecology, agriculture, and
habitability. This image of Southern
California, from the desert at Mojave to the
ocean at Ventura, shows a variety of
landscapes and environments.
This perspective view was generated by
draping a Landsat satellite image over a
preliminary topographic map, acquired by
the Shuttle Radar Topography Mission
(SRTM) aboard the Space Shuttle
Endeavour in February 2000. It shows the
Tehachapi Mountains in the right
foreground, the city of Ventura on the coast
at the distant left, and the easternmost
Santa Ynez Mountains forming the skyline
at the distant right.
Image credit: NASA/JPL, National Imagery and Mapping Agency
The Mojave DesertThe Mojave Desert
Vegetation on Mount St. Helens is
actively recovering from the massive
eruption on May 18, 1980, as seen in
this image. Landsat 7 acquired the
larger image on August 22, 1999.
Some of the effects of the eruption
can still be seen clearly, especially on
the northern and eastern flanks of the
mountain, which are still mostly
barren (shades of white and light
gray). The crater is in the center of
the image.
Landsat 7 image credit: U.S. Geological Survey EROS Data Center and Landsat 7 Science Team
Mount St. HelensMount St. Helens
This image of Mount St. Helens was
acquired by ASTER on August 8, 2000
and covers an area of 37 by 51
kilometers (about 23 by 32 miles).
Topography has been exaggerated 2
times to enhance the appearance of
the relief.
ASTER image credit: NASA/GSFC, METI/ERSDAC/JAROS, and U.S./Japan ASTER Science Team
Mount St. HelensMount St. Helens
This image, acquired by ASTER on
August 24, 2000, shows the extent of
deforestation in the state of
Rondonia, Brazil. Tropical rainforest
appears red and cleared land appears
light gray.
The Amazon Basin is the largest
continuous region of tropical forest in
the world, containing nearly 31% of
the world’s total. Monitoring global
deforestation here provides critical
information on the Earth as a system,
as plant cover interacts with the air,
soil, and water in many ways.
Image credit: NASA/GSFC, METI/ERSDAC/JAROS, and U.S./Japan ASTER Science Team
Views of DeforestationViews of Deforestation
This image, acquired from Landsat 7 on August 1, 2000, shows how a large agricultural development effort, called the Tierras Baja project, and resettlement of people from the Andean high plains have brought rapid deforestation of the tropical dry forest in Santa Cruz de la Sierra, Bolivia. The radial patterned fields are part of the San Javier resettlement scheme.
Image credit: U.S. Geological Survey EROS Data Center and Landsat 7 Science Team
Views of DeforestationViews of Deforestation
Carbon is key to life, and it moves
throughout the Earth system in a major
biogeochemical cycle. Photosynthesis by
land plants plays an important role in that
cycle. As seen in this illustration, carbon
dioxide from the surrounding air is
absorbed by the tree and converted to
oxygen, which is then released back into
the air during photosynthesis. This process
results in a net removal of carbon dioxide
from the air and its storage in the tissues
of plants. In this way, carbon moves from
one sphere of the Earth system (the air) to
another (the land), where it is temporarily
stored. (Dry wood is about 50% carbon.)
Natural CO2 CycleNatural CO2 Cycle
When forests die and decay or
are burned, large amounts of
plant tissue, known as
biomass, are oxidized, and
carbon dioxide returns to the
air. The burning of tropical
forests has increased
dramatically in recent decades
and currently releases about
10 to 20% as much carbon
dioxide into the atmosphere as
the burning of fossil fuels. The
effects of that increase in
carbon dioxide ripple
throughout the Earth system,
and monitoring these changes
by satellite is essential.
Biomass Burning and CO2Biomass Burning and CO2
Natural resource managers have new tools
for their work with satellite imagery.
About 100 Landsat scenes appear in this
image of Southeast Asia. With satellite
remote sensing and Geographic
Information Systems (GIS) technology,
scientists can accurately measure the rate
of change and extent of tropical
deforestation. With these data, they can
determine the net release from the forest
to the atmosphere of important trace
gases such as carbon dioxide, which
impact climate and other aspects of the
Earth system.
Images credit: Tropical Rain Forest Information Center, Basic Science and Remote Sensing Initiative at Michigan State University (A member of the NASA Federation of Earth Science Information Partners)
Vegetation in Southeast AsiaVegetation in Southeast Asia
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Introduce major concepts of “Land – Our Changing Earth” by
dividing the class into small teams to research several of the
questions on the next page. Students can research their
answers using these slides and other sources. Students can
prepare presentations to cooperatively instruct other teams
using pre-established teacher criteria.
Introduce major concepts of “Land – Our Changing Earth” by
dividing the class into small teams to research several of the
questions on the next page. Students can research their
answers using these slides and other sources. Students can
prepare presentations to cooperatively instruct other teams
using pre-established teacher criteria.
For the Classroom…For the Classroom…
• How does the Earth’s land surface change through time?
• What are some of the ways people change the Earth’s land surface?
• Where is the destruction of forests taking place most rapidly, and why there?
• How might land cover and land use changes affect wildlife and plants?
• What are some of the ways that events and processes taking place on the land surface affect the atmosphere?
• How can people use satellite observations to prevent and fight fires?
• What do Earth-observing satellites show us that can help us decide where and how to live?
• What can satellite images tell us about natural hazards such as volcanoes, fires, floods and drought?
• How does the Earth’s land surface change through time?
• What are some of the ways people change the Earth’s land surface?
• Where is the destruction of forests taking place most rapidly, and why there?
• How might land cover and land use changes affect wildlife and plants?
• What are some of the ways that events and processes taking place on the land surface affect the atmosphere?
• How can people use satellite observations to prevent and fight fires?
• What do Earth-observing satellites show us that can help us decide where and how to live?
• What can satellite images tell us about natural hazards such as volcanoes, fires, floods and drought?
For the Classroom…For the Classroom…