CHAPTER 14 SECTIONS > Forest Monitoring | Volcanology | Land Surface Simulations | Coral Reef Mapping
Monitoring Temperate Forests
Curtis E. Woodcock - Boston University
Fire, drought, and humans all can destroy forests and their ecosystems.
While much attention is paid to deforestation in tropical rainforests,
very few comprehensive studies have been done to address changes
in the Earth's temperate conifer forests. Temperate conifer forests
lie at latitudes above tropical forests and below boreal forests
and account for much of the forested area in the United States and
Understanding changes occurring in temperate conifer forests is
important for understanding environmental issues including wildlife
habitat protection, watershed management, timber harvest, and understanding
the role of human activities on changes in regional climates.
Previously, researchers have only been able to monitor changes
in specific locations with Landsat data due to its limited availability.
Boston University geographer Curtis E. Woodcock and colleagues used
Landsat to monitor how drought in the late 1980s and early 1990s
affected forests in California's Sierra Nevada. During the drought,
Woodcock found that Landsat images could recognize areas where trees
were dying due to lack of water, a factor making the trees more
susceptible to disease and the forest more susceptible to fire.
The practice of clearcutting sections of Washington's Olympic National
Forest and other state forests in the Pacific Northwest was prevalent
up until the late 1980s when changes in public policy caused logging
to move from public to private land.
With the help of the frequent and comprehensive coverage of Landsat
7, Woodcock and colleagues plan to create a global monitoring system
for temperate conifer forests. The monitoring system will measure
the rates of destruction of conifer forests due to natural causes
such as drought and fire and anthropogenic clearing due to harvest
or development of forest lands. The monitoring system will also
track the regrowth of forests and successional change in vegetation.
The new system will work in conjunction with NASA EOS land cover
change studies based on the EOS Moderate-resolution Imaging Spectroradiometer
(MODIS). The MODIS instrument will fly aboard the Terra satellite
set for launch in July 1999, and will be used to identify large
areas of significant changes in forest lands. Following up with
the finer spatial resolution data from Landsat will allow determination
of the type of changes and their geographic extent.
Using Landsat images of Washington's Olympic Peninsula (above),
Boston University researchers can keep track of what areas are being
cut, and what areas of forest are regrowing. The square box in this
1986 image represents a square kilometer area within the Olympic
The two sub-scenes above are from September, 1987 (top) and September,
1995 (bottom). In each sub-scene, there are clearcut patches (red)
in the northern two thirds of the image. Much of the clearcutting
occurred prior to 1984. However, new clearcuts are evident in images
of this area through 1987. After 1987, there is evidence of regrowing
vegetation in the clearcut patches. In the southern portion of the
images, the forest is undisturbed; this portion lies within the
Olympic National Park.