|Biological Diversity||Ecosystem Condition and Productivity||Soil and Water||Role in Global Ecological Cycles||Economic and Social Benefits||Society's Responsibility|
|Ecosystem Diversity||Species Diversity||Genetic Diversity|
|Indicator 1.1.1 Area of forest, by type and age class, and wetlands in each ecozone||Indicator 1.1.2 Area of forest, by type and age class, and wetlands in each ecozone|
Indicator 1.1.1 - Area of forest, by type and age class,and wetlands in each ecozone
Forest type and age class
Tracking major forest types according to ecozone provides information on the extent and variety of habitat for forest species and thus provides a simple synopsis of changing forest biodiversity.
Recently released statistics from Canada's Forest Inventory (CanFI 2001), a compilation of existing forest inventories, indicate that there are 402.1 million ha of forest and other wooded land in Canada. The other wooded land makes up 23% of this area and includes treed wetlands as well as land with slow-growing, scattered trees. Since CanFI 2001 differs from the previous inventory (CanFI 1991) in several ways, these data cannot be compared meaningfully. Definitions and methodologies have been changed, the inventory coverage has been extended to include all Canada's land area, and more land cover classes are used to reflect a focus on the forest rather than on timber. Measurement methodology has also been changed, particularly in northern Canada. In 1991, the forest north of 60º latitude was delineated using maps generated in the early 1980s or before. CanFI 2001, however, relies on satellite interpretation, which improves our ability to differentiate forest from nonforest areas. As a result, some areas that were thought previously to be forest area are, in fact, not forest. Therefore comparisons between the 1991 and 2001 CanFI inventories would be misleading (Natural Resources Canada 2004).
The difference between the total forest area of 417.6 million ha, presented in the previous criteria and indicators report (CCFM 2000), and the current figure of 402.1 million ha largely reflects updated methodology rather than a change in the area of the forest land base.
Table 1.1a provides a breakdown of the area of Canada's forest by terrestrial ecozone and provides information on the distribution of forest cover types. Canada's nonstocked forest (about 127 million ha) was not classified by forest type or age class in CanFI 2001. Also, limitations of the inventory prohibit some vast areas of stocked forest from being reliably aged, so no age class could be assigned for the additional 102 million ha of stocked forest. The remaining 173 million ha of stocked forest is classified by forest type and age class. Softwood forests form the largest forest type, occupying almost 62.5% (about 108 million ha) of the stocked forest classified by age. Mixedwoods comprise 21.2% (about 37 million ha) of this area and hardwoods 15.7% (about 27 million ha). Most of Canada's softwood forest lies in the boreal ecozones, which are dominated by this cover type.
Table 1.1a Area of Canada's forest by terrestrial ecozone and the distribution of forest cover types. (Source: CanFI 2001)
The smaller boreal hardwood forest is largely composed of aspen and birch stands. The only ecozones with a predominance of hardwood stands are the Mixedwood Plains of southern Ontario and Quebec and the Prairies ecozone.
Figure 1.1a shows the age-class distributions by forest type on stocked forest land for forest ecozones in Canada. The dominant age class of Canada's forests is 41-80 years, which, between the three forest types combined, covers almost 56 million ha of the stocked forest. The oldest age-class category (161+) covers 17.6 million ha, and all but 522 000 ha of this is softwood. The uneven-aged category is not used by all jurisdictions, so that area is somewhat underestimated.
Figure 1.1a Age-class distribution by forest type on stocked forest land as a percentage of the total stocked, aged forest area in major forest ecozones.
The Pacific Maritime ecozone is composed of primarily the temperate rain forests of the west coast. Stand replacing fires are rare in this ecozone. The lack of widespread major disturbances is reflected in the age of much of the forest in the ecozone. In contrast, the oldest forests in the boreal ecozones (Taiga Plains, Taiga Shield, Boreal Shield, Atlantic Maritime, Boreal Plains, Taiga Cordillera, Boreal Cordillera, Hudson Plains) tend to be between 100 and 160 years old. This age-class component of the boreal forest reflects the more abundant occurrence of stand-replacing wildfire than found in the coastal forest. The preponderance of young age classes in the Atlantic Maritime and Mixedwood Plains ecozones reflects a largely regenerating forest component after forest harvesting.
Wetland ecosystems provide essential habitat to a myriad of wildlife species including migratory birds. Boreal wetlands provide food and shelter for keystone species such as moose and deer and small mammals such as the beaver, muskrat, and marten. Loss of total area of wetland for a given ecozone may indicate loss of habitat, food, or shelter for these wildlife. In addition, forest wetlands are major sources of recharge for groundwater and for regulating flows of surface waters. Forest activities resulting in the loss of or the pollution of wetlands would have consequences on both groundwater and surface water quality and quantity.
Wetlands cover about 15% of the land area of Canada. They were once abundantly distributed throughout the country. Recently, however, wetlands have become an increasingly scarce resource in settled areas of the country. Throughout Canada, wetlands have been adversely affected by land use practices that have caused destruction of vegetation, nutrient and toxic loading, sedimentation, and altered flow regimes. For example, in southern Ontario, 68% of the original wetlands have been converted from their natural state to support alternative uses such as agriculture and housing. Similarly, only about 25% of the original wetlands of the pothole region of southwestern Manitoba remain. In the North, however, most of the wetlands are intact (The Atlas of Canada 2004).
No data are currently available on change in total area of wetlands by ecozone. The data provided are a benchmark for further analysis of change when the new National Forest Inventory is operational. Canada is estimated to have 134.6 million ha of wetlands (Table 1.1b), approximately 25% of the world's wetlands. The Hudson Plains ecozone has the largest percentage of total wetland of all the ecozones. In fact, this ecozone may contain the largest coextensive wetland on earth (Wiken et al. 1996). The boreal ecozones combined contain almost 100 million ha of wetland of which 60-92% are treed depending on the ecozone.
Figure 1.1b Area of wetlands by ecozone (Source: CanFl 2001)
Recognizing the ecological importance of wetlands, several provinces have instituted wetland inventories. Ontario has developed a wetland ecosystem classification for northwestern Ontario (Harris et al. 1996) and is working to extend the classification to other portions of the province.
Alberta has carried out a peatland inventory (Vitt et al. 1998), following closely the Canadian Wetland Classification System and mapping wetlands in the province at a scale of 1:250 000.
British Columbia has also developed a wetland classification system for the province (Mackenzie and Moran 2004). This system provides a framework for identifying and describing wetlands, organizing management experience, and promoting a better understanding of wetlands and related ecosystems. Drawing on the national classification (National Wetlands Working Group 1988), the system includes bogs, fens, marshes, swamps, and shallow waters and describes estuarine, flood zone, and transition types of ecosystems.