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Ministry of Natural Resources
State of resources reporting
October 2010
The State of Forest Carbon
in Ontario
Ontario’s managed forests have the potential to remove carbon dioxide, a
greenhouse gas, from the atmosphere and thereby slow global warming.
What is forest carbon?
Carbon is a chemical element that is a key
building block of life on Earth. It is the basis for
all life forms, from microbes to plants to animals
to people. The carbon cycle describes how
carbon moves through land, water, and air as
plants and animals live, die, and decompose.
Carbon exists naturally in the atmosphere in the
form of carbon dioxide and other compounds.
Carbon dioxide is one of many greenhouse
gases that trap heat in the atmosphere and make
life on Earth possible. Human activities such
as burning fossil fuels increase the amount of
carbon dioxide in the atmosphere and contribute
to global warming.
Forests take up carbon dioxide through
photosynthesis and convert it to wood and
other plant parts. Forests therefore have the
potential to help remove carbon dioxide from
the atmosphere and to slow global warming.
If more carbon can be stored in forests and
wood products (e.g., lumber, furniture, and
paper), then less carbon dioxide will remain in
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the atmosphere. To understand how best to
manage the carbon in Ontario’s forests, forestry
professionals need to know how much carbon is
contained in forests and wood products and how
that amount changes over time.
Researchers around the world are working
to estimate the amount of carbon stored in
trees, soil, and harvested wood products. Their
methods vary, but they agree that accurate
accounting is needed. Ontario is focussing on
determining the potential for carbon storage in
the managed forest.
Background
The forest carbon cycle is defined as the
combined processes—including photosynthesis,
decomposition, and plant respiration—by
which carbon moves between the atmosphere,
soils, water, and living organisms. The forest
carbon cycle can be extended to include forest
harvesting and wood manufacturing, as well as
the use and disposal of wood products (Figure 1).
State of resources reporting
October 2010
The most accurate estimates available are for
above ground tree carbon (trunks, stems, and
leaves). Estimates of root carbon and soil carbon
are less certain because they are more difficult
and costly to measure.
How is forest carbon estimated?
Estimates of forest carbon can vary depending
on the researcher’s approach and assumptions.
For example, in their calculations, researchers
might:
• Treat climate as a constant over time or adjust
climate to reflect potential future changes
Figure 1: The forest carbon cycle.
• Treat rates of disturbance (such as fire) as
a constant over time or adjust to reflect
potential changes in disturbance regimes in
the future
Photosynthesis is the process by which
plants use sunlight and carbon dioxide to
grow. Carbon dioxide is absorbed from the
atmosphere and combined with water to
create wood, stems, roots, and leaves. At
night, leaf cell nutrients are consumed to
provide energy for the plant, and carbon
dioxide is released back to the atmosphere
through plant respiration.
• Include wood products, which store carbon
long after the trees are harvested, into their
calculations or ignore carbon stored in wood
products
Fallen leaves and branches, dead trees, and
decaying root systems are broken down
by insects, fungi, and other soil organisms.
Some of the carbon in this decaying material
attaches to soil particles and remains in the
soil, some is emitted to the atmosphere as
carbon dioxide, and the rest dissolves in
water and is carried into rivers, streams, and
lakes. Forests also release carbon dioxide
when there is a natural disturbance, such as
a forest fire.
In short, forests take up carbon dioxide from
the atmosphere through photosynthesis,
and release it through respiration,
decomposition, and forest fires. Forests are
considered ‘carbon sinks’ when their trees
and plants absorb and store more carbon
dioxide from air than the forest emits by
fire, decomposition, and respiration in a
given time period. Conversely, forests are
considered ‘carbon sources’ when more
carbon dioxide is emitted than removed.
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• Assume that soil carbon is constant, since
little is known about how forest management
and climate change affect this pool or
attempt to estimate how soil carbon could
change over time
As a result of differing assumptions, carbon stock
estimates can differ greatly. It is important to
understand what approach and assumptions are
used for each set of estimates.
To estimate carbon stocks accurately, researchers
need to know about more than just the natural
processes and how they are influenced by
management. They also need to know how
the carbon balance is affected by substituting
wood for fossil fuels and carbon-intensive
construction material, such as steel or concrete
and burning fossil fuels during tree harvesting,
log transporting, and processing wood products.
In short, many factors affect estimates of
carbon stocks associated with managed forests.
Researchers have estimated the amount of
carbon stored in Ontario’s managed forest
(Figure 2). These estimates include the carbon in:
State of resources reporting
October 2010
Ministry of Natural Resources researchers used
the forest carbon modelling software FORCARBON, developed for Ontario, to estimate
current and future forest carbon stocks based
on approved forest management plans. Their
results show when and to what extent Ontario’s
managed forests will act as carbon sinks and
contribute to mitigating climate change. Future
work will examine how forests may respond to a
changing climate. This will allow researchers to
better estimate forest carbon stocks.
}
Managed
forest
area
Over the 100-year period from 2001 to 2100,
the managed forest (green bars) will likely be
a carbon sink (Figure 3). This result does not
include carbon emissions from non-forested
wetlands and assumes that soil carbon will remain
at current levels. For some decades (2031–2060),
however, Ontario’s managed forest will likely be a
carbon source.
Figure 2. The managed forest area used in carbon
calculations excludes southern Ontario and most
of the Far North, but includes the measured fire
management zone (red line).
• Live tree biomass (all the living parts of the
tree, above and below ground)
When researchers included the carbon contained
in wood products (dark red bars) in their
estimates, they found that, after 100 years, five
times more carbon will be added to carbon
stored in wood products than will be added
in forests. Overall, more carbon will be stored
in Ontario’s managed forest area and in wood
products than is released throughout the century
(black bars).
• Understory plants
• Standing and fallen dead trees
• Forest floor (layer of leaves and other
organic material lying on top of the soil)
• Soil
Figure 3. Carbon
change in Ontario
for 2001 to 2100,
estimated by decade
for managed forests,
for wood products,
and overall.
Decadal carbon changes (Mt)
Carbon estimates for Ontario’s managed
forests include the carbon stored in wood
products as well as the carbon emitted during
their manufacturing, use, and disposal.
Decade
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State of resources reporting
October 2010
Changes in climate can affect how much
carbon forests store. For example, a longer
growing season may increase the amount
of carbon stored in forests. If conditions
change such that the amount of rainfall is
not sufficient to support tree growth, then
less carbon will be stored. Fire and pest
outbreaks resulting from drier conditions
could also increase tree mortality rates and
cause forests to emit more carbon.
• Where feasible, protecting forests from fire
and insects
• Minimizing deforestation and planting trees in
open areas, particularly in southern Ontario
• Promoting the use of wood products to store
carbon for long periods
Management of forest carbon
Forest management activities can affect
the amount of carbon stored in a forest
by influencing, for example, the amount
of forest cover, the growth rate of trees,
and the extent to which forest soils are
disturbed. Establishing new trees after
harvest and tending them to promote
growth will help to increase stored carbon.
Delaying regeneration or unnecessarily
reducing forested area by excessive road
building will reduce stored carbon. Some
forest managers are already working to
include carbon assessments in their forest
management plans to help determine the
effects of forest management activities on
carbon storage. Forest carbon storage is
one of a number of values that could be
considered in implementing a sustainable
forest management program.
In general, the amount of carbon stored
in Ontario’s forests can be increased by
protecting forests from natural disturbances,
increasing forest growth rates, converting
non-forested areas to forests, and avoiding
deforestation (permanent removal of
Photo: Heather Bickle
forests). Today, the Ontario government is:
• Promoting the rapid establishment of
new forests after harvest
• Increasing growth rates by ensuring that
tree species are planted on suitable sites
and using seed from the best-quality
trees
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State of resources reporting
October 2010
Life cycle analysis of wood products
Planting 50 million trees by 2020
to sequester carbon
Researchers are examining the amount of
carbon emitted at each stage of the life
cycle of a wood product, including harvest,
transport, manufacture, delivery, use, and
disposal. This work is known as life cycle
analysis.
An Ontario government tree planting initiative
in southern Ontario is increasing carbon
storage by establishing trees in areas that were
previously converted to non-forest uses. This
effort will also:
• Help to diversify southern Ontario’s
landscape by replacing forests lost to the
construction of new homes, businesses, and
farms
• Provide shade and moderate local
temperature extremes
• Help to conserve local soil and water quality
• Provide wildlife habitat
Through Trees Ontario, more than 5.7 million
trees have been planted as part of this initiative
in partnership with conservation authorities,
stewardship councils and other organizations
across southern Ontario. As well, MNR
partnered with Evergreen to plant 100,000 trees
in communities across the province.
Research in Ontario on the expected life
cycle of wood products is in its infancy,
but some information is available from
other areas. When trees are harvested,
50 to 75 percent of the wood is used in
wood products. Depending on the type of
product and what happens to it over time,
a product can store carbon for a few years
to many decades. Most wood products
enter the landfill after retaining carbon
for long periods and continue to retain
carbon for some time before decaying.
Outlook for forest carbon
Researchers continue to improve their understanding and estimates of forest carbon. In general,
given today’s management practices and harvest rates and moderate changes in climate,
estimates show that Ontario’s managed forests should be a small carbon sink over the next
century. When wood products are factored into carbon estimates, Ontario’s forests are expected
to be a larger carbon sink.
Continued changes in climate will affect future forest carbon stocks. Researchers are working
to understand the extent of the effects and to determine effective mitigation methods. As the
scientific knowledge increases, forest managers will have a better understanding of how their
management decisions affect forest carbon stocks.
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State of resources reporting
October 2010
What you can do to help
• Choose wood products over non-renewable or less energy efficient building materials.
• Plant trees to take up and store more carbon (remember to tend the trees to ensure they
grow).
• Promote tree health by protecting trees on your property from damage and replacing
those that are declining.
Information sources
• Chen, J., S.J. Colombo, M.T. Ter-Mikaelian, and L.S. Heath. 2008. Future carbon storage
in harvested wood products from Ontario’s Crown forests. Canadian Journal of Forest
Research. 38(7): 1947–1958.
• Chen, J., S.J. Colombo, M.T. Ter-Mikaelian, and L.S. Heath. 2010. Carbon budget of
Ontario’s managed forests and harvested wood products, 2001–2100. Forest Ecology and
Management. 259: 1385–1398.
• Parker, W.C., G. Nielsen, J. Gleeson and R. Keen. 2009. Forecasting carbon storage and
carbon offsets for southern Ontario afforestation projects: the 50 million tree planting
program. Ontario Ministry of Natural Resources, Applied Research and Development
Branch, Sault Ste. Marie, ON. Climate Change Research Note CCRN-10. 8 p.
Related information
• Climate change in MNR (ontario.ca/mnr; select Climate Change)
• GoGreen Ontario (http://www.ene.gov.on.ca/en/air/climatechange/ourplan.php)
• Ontario Forest Research Institute (ontario.ca/ofri; select OFRI research)
• Trees Ontario (http://www.treesontario.ca/)
• Evergreen (http://www.evergreen.ca/)
For more information
For more information on the status of forest carbon in
Ontario, please contact:
ISBN
ISBN
State of Resources Reporting
Ontario Ministry of Natural Resources
Inventory, Monitoring and Assessment Section
300 Water Street
Peterborough ON K9J 8M5
978-1-4435-5686-6 PDF
978-1-4435-5685-9 HTML
[email protected]
ontario.ca/stateofresources 6