Biological Diversity Ecosystem Condition and Productivity Soil and Water Role in Global Ecological Cycles Economic and Social Benefits Society's Responsibility
Carbon Cycle
Indicator 4.1.1 - Net change in forest ecosystem carbon Indicator 4.1.2 - Forest ecosystem carbon storage by forest type and age class Indicator 4.1.3 - Net change in forest products carbon Indicator 4.1.4 - Forest sector carbon emissions


Carbon Cycle

Concentrations of greenhouse gases in the atmosphere are increasing as a result of human activities. Observed increases in global temperatures over the past 50 years are believed to be attributable to these activities and it is thought that future effects will be potentially more serious. The major source of greenhouse gas emissions is the burning of fossil fuels, and the major greenhouse gas in terms of volume emitted is carbon dioxide (CO2). Global ecological cycles are believed to be negatively affected by the accelerated release of CO2 into the atmosphere.

Forests absorb and store atmospheric CO2 to produce the carbohydrates they require for growth through photosynthesis and they release CO2 into the atmosphere through decay, fires, and other processes. Forests therefore play a key role in the global carbon cycle and the climate. Increasing carbon stocks in the forest ecosystem could play a role in mitigating climate change. Carbon stock changes and their impact on the total amount of carbon stored in Canada’s forest ecosystems can be tracked with the help of the Carbon Budget Model of the Canadian Forest Sector, developed and maintained by the Canadian Forest Service and assisted by the provincial and territorial governments. This model forms the basis of Indicators 4.1.1 and 4.1.2, which describe these carbon stock exchanges over time and the total amount of carbon stored in Canada’s forests.

Currently, Canadian researchers are refining the Canadian carbon budget model to improve future reporting, thus national results were not available in time for this report. When their work is complete, this improved carbon model will be based on the most current science and will be consistent with other national reporting processes on forest carbon such as the United Nations Framework Convention on Climate Change (UNFCCC) and the Kyoto Protocol. It will also provide consistent data that will facilitate comparisons between indicator reporting periods, and allow the inclusion of revised or new data, such as those generated by the new National Forest Inventory. Because of the lack of data available at this time, it is impossible to properly assess the impact of carbon stock changes on the sustainability of Canada’s forests. Indicators 4.1.1 and 4.1.2 instead focus on a case study based on the Boreal Plains ecozone in Saskatchewan and Manitoba.

Canada’s forests support a strong forest industry. When forests are harvested to extract timber products, the carbon contained in the trees is transferred to these products and remains locked up for days, years, or decades, depending on how they were manufactured and used (Indicator 4.1.3). Therefore, although forest harvesting does not release carbon to the atmosphere immediately, forest products will eventually release their carbon to the atmosphere.

Therefore, it is important to understand the carbon life cycle in forest products to improve knowledge of the potential impact of this carbon on the country’s overall carbon balance. Despite having a much smaller impact than the other components of the carbon cycle, carbon stocks of forest products in Canada have been increasing since the early 1990s.

The forest industry uses large quantities of energy in harvesting, transporting, and processing timber to manufacture these products. As a result, the forest sector is the largest single industrial energy user in Canada and has significant GHG emissions (Indicator 4.1.4). Although high, these emissions (direct emissions plus indirect emissions from electricity purchased by the sector) in 2002 were unchanged from 1980, despite a 23% increase in energy use and a 30% increase in pulp and paper production. Significant improvements in energy efficiency and greater reliance on cleaner fuels, such as bioenergy, helped to limit growth in both energy use and emissions.

The longevity and large area of standing crops can make forest ecosystems particularly well adapted to long-term positive carbon balance. Conversely, conversion of forest lands to low biomass, shortlived standing crops with rapid turnover rates, or the permanent removal of forest cover, can reduce the land's capacity to absorb and store carbon. For this reason, information on the area of forest (Indicator 1.1.1), additions and deletions of the forest area (Indicator 2.2), and the area disturbed by fires, insects, disease, and harvesting (Indicator 2.3) provide important supplemental information when discussing forest contributions to the global carbon budget.