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 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). 1
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: Figure 1: The forest carbon cycle. 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. 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. Treat climate as a constant over time or adjust climate to reflect potential future changes Treat rates of disturbance (such as fire) as a constant over time or adjust to reflect potential changes in disturbance regimes in the future Include wood products, which store carbon long after the trees are harvested, into their calculations or ignore carbon stored in wood products 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: 2
}Managed forest area 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) Understory plants Standing and fallen dead trees Forest floor (layer of leaves and other organic material lying on top of the soil) Soil 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. Ministry of Natural Resources researchers used the forest carbon modelling software FORCARB- ON, 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. 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. 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). 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) Decade 3
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 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 Photo: Heather Bickle 4
Life cycle analysis of wood products 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. 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. Planting 50 million trees by 2020 to sequester carbon 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. 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. 5
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 ISBN ISBN 978-1-4435-5686-6 PDF 978-1-4435-5685-9 HTML For more information on the status of forest carbon in Ontario, please contact: State of Resources Reporting Ontario Ministry of Natural Resources Inventory, Monitoring and Assessment Section 300 Water Street Peterborough ON K9J 8M5 SORR@ontario.ca ontario.ca/stateofresources 6