Canadian Forest Service researchers are developing a reliable generic method of detecting and monitoring deforestation and its carbon consequences.
By using satellite images from two time periods, probable deforestation
areas are determined.
A: 1990
B: 2000; yellow lines indicate deforestation.
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As human history demonstrates,
the conversion of forests to other uses - deforestation - is not a modern
phenomenon. But exactly how much forest is disappearing and how does that
affect the amount of carbon dioxide in the atmosphere? Canadian
Forest Service scientists are developing a way to answer that question
by tracking deforestation and its consequences.
"Current estimates on deforestation in Canada are based on the best
knowledge available," says Dr. Don Leckie (available at dleckie@pfc.cfs.nrcan.gc.ca),
a research scientist at the Pacific Forestry Centre, "but sometimes
it has been difficult to obtain reliable information."
Canada will be required to report on the consequences of deforestation
if the Kyoto Protocol is ratified. Also, the United Nations Framework
Convention on Climate Change requires reporting on deforestation as part
of its national greenhouse gas emissions and removal inventory. Dr. Leckie
and other Canadian Forest Service researchers are developing a reliable
generic method of detecting and monitoring deforestation and its carbon
consequences.
The core design is based on the new National Forest Inventory sampling
network, supported by satellite imagery and aerial photography. The basic
National Forest Inventory sampling network consists of 2 X 2-km plots
on a 20 km grid for which land cover and stand attributes are interpreted
from medium- scale aerial photography. Using satellite images from two
time periods, forest clearings are highlighted and probable deforestation
areas are delineated for an enhanced sampling grid every 10 km or denser.
Some areas, close to urban development, may be obvious cases of deforestation.
Aerial photography, high resolution satellite data, map information, existing
records and on-the-ground visual interpretation will also be used to help
confirm some cases of uncertain interpretation. Satellite image interpretation
will be adjusted according to known deforestation cases on National Forest
Inventory plots determined from air photo interpretations as part of the
National Forest Inventory system.
"To test the design, a joint project has been developed between
the Pacific Forestry Centre, the Geomatics and Data Acquisition section
of the Ontario Ministry of Natural Resources, the Eastern Ontario Model
Forest and Environment Canada's Greenhouse Gas Division," says Dr.
Leckie. "Two test sites have been identified: 5,000 km2 of
Leeds-Grenville County, which includes part of the Eastern Ontario Model
Forest, and another 9,100 km2 in Simcoe County. On both sites, the
results will be interpreted and then compared with photo interpretation
of National Forest Inventory plots."
When areas of deforestation have been identified, the next step will
be to estimate the amount carbon stock removed. The deforestation estimation
work is part of a larger effort and is combined with work of a Canadian
Forest Service team developing the Carbon Budget Model of the Canadian
Forest Sector to determine the carbon consequences of the deforestation.
The stock of carbon on each site prior to deforestation will be estimated
by reference to the existing forest inventory information for that site
or from average carbon stocks for similar stand types in the region. Carbon
accumulation from the new land cover will be accounted for in general
terms by estimation and modeling based on the typical values for the new
surface cover. The Canadian Carbon Budget Model of the Canadian Forest
Sector will be used as the basis for the various carbon estimates.
In a country the size of Canada, our vast land base and irregular spatial
pattern of deforestation activities pose a challenge for the development
of a reliable, operational deforestation monitoring and greenhouse gas
accounting system. The integrated system being developed at the Pacific
Forestry Centre should form a sound basis for a national deforestation
measuring and reporting system.
Special
issue on Climate Change and Forest Carbon Accounting in Canada.
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