Pacific Maritime Ecozone

Changing Forest Landscape Conditions

Healthy high-elevation forests: High-elevation forests, dominated by mountain hemlock and subalpine fir, cover approximately 4 million ha within the ecozone. These forests are considered healthy.

Coastal Douglas-fir forests: Coastal Douglas-fir forests originally covered approximately 200 000 ha. Today, approximately 140 000 ha of forest remain, the rest having been converted to urban or agricultural uses. This forest is predominantly younger than 100 years old due to a combination of harvesting and fires. These forests continue to be converted to non-forest uses predominantly for urban and agricultural pursuits (MacKinnon and Eng 1995).

Coastal temperate rainforest and harvesting: This ecozone contains 25% of the remaining coastal temperate rainforest worldwide (MacKinnon and Eng 1995). The vast majority of regenerating and young forests result from logging, as stand-destroying, natural disturbances are very uncommon in this ecozone. Area estimates show that approximately 24% of this forest, within British Columbia, has been logged and reforested; an additional 3% of the total area has been logged and urbanized (MacKinnon and Eng 1995). Logging is a major land-use activity within the ecozone, covering approximately 50 000 ha annually (British Columbia Ministry of Forests 1994; Environment Canada 1995). Overall, more than 55% of trees in the remaining rainforest, which is dominated by western hemlock and western red cedar, are more than 250 years old (MacKinnon and Eng 1995).

Garbutt and Allen (1998) indicate that forest management practices, such as species conversion, may be causing changes in insect and disease dynamics that differ from those associated with the original coastal forest. Some earlier research (Tkacz and Hansen 1982) has indicated that, in areas where Douglas-fir has been widely planted to replace western hemlock, a slower growing species, the incidence of Phellinus root disease has increased. This increase is attributable to the resultant `pure' stands of Douglas-fir, which have less spatial and age diversity than the original stands dominated by western hemlock.

Changing Biodiversity

Old growth: The loss, through harvest, of the old growth of the coastal temperate rainforest is of public concern. Once harvested, the ecological dynamics and structure of these forests may be permanently altered as the regenerating forest will likely be harvested before an old-growth ecosystem is attained.

Recently, previously unknown invertebrate species, unique to the canopies of coastal old-growth forests of this ecozone, have been identified (Humble et al. 1997). Many wildlife species, including birds such as the spotted-owl and the marbled murrelet, rely on old-growth coastal forests (Cannings 1994). As the area of old growth is reduced, wildlife habitat and other ecological values and functions that these ecosystems provide are also reduced (Clayoquot Sound Scientific Panel 1995).

More: Concept of Old Growth

Garry oak - Arbutus ecosystem: This ecosystem is one of the rarest forest ecosystems in British Columbia and does not occur elsewhere in Canada (British Columbia Ministry of Environment, Lands and Parks 1993). In British Columbia, it is restricted to the southeast coast of Vancouver Island and the southern Gulf Islands. During the last 150 years, agricultural and urban development severely reduced its extent. The decline has been particularly dramatic in the last three decades. Fire suppression has allowed invasion by Douglas-fir. Overgrazing by livestock and the eastern cottontail rabbit, an introduced species, has created conditions for the establishment of many non-native plant species. European gypsy moth and Scotch broom, both non-native species introduced through human activity, are also continuing threats to native species. Considerable public effort is underway to plant Garry oak and to protect the existing tree population (British Columbia Ministry of Environment, Lands and Parks 1993).

Changing Atmospheric Environment

Smog episodes - a concern? : Forests in the southwestern portion of this ecozone are exposed to damaging concentrations of tropospheric (ground-level) ozone or smog originating from industrial and urban activity associated with the Lower Mainland of British Columbia (Dann and Summers 1997). The Lower Mainland is, in fact, one of three areas within Canada that regularly experience episodic events of ground-level ozone pollution at levels injurious to both human and plant health. Ozone-like damage symptoms have been reported on western white pines. Direct short-term effects on native species would not be expected at measured ozone levels (Pearson and Percy 1997). Repeated exposure over several seasons, however, can lead to cumulative growth effects or predisposition to other stressors of forest health (Runeckles and Wright 1996).