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GLOBAL IMPACTS : C RITERION F OUR Indicator 4.1 Ground level ozone and pollution deposition
Indicator 4.2 Climate trends
Global impacts such as climate change and pollution are major issues facing Canada and the world. Forests play an important role in global ecological cycles by recycling the Earth’s water, carbon, oxygen, and other life-sustaining elements. Impacts such as global warming and pollution can threaten the “recycling” capacity of the forests. Knowledge of the impact associated with such things as ground level ozone and global warming is important to ensure that the forests – and the demands placed on them – are sustainable.
Quick Facts Ground level ozone: • Along with acid precipitation, ground level ozone is one of the two main regional air pollutants in Ontario. • Ground level ozone concentrations in the EOMF are periodically above the critical level causing leaf discoloration and premature leaf drop to sensitive tree species. Climate change: • Climate change is a major factor determining the sustainability of our forests. A warming climate could alter where a tree species will grow, and result in increased intensity of fires and drought.
INDICATOR 4.1: GROUND LEVEL OZONE AND POLLUTION DEPOSITION Description: Ground level ozone is a pollutant that is produced when sunlight passes through high concentrations of airborne industrial pollutants. When ozone levels become too high, they become toxic to vegetation, altering the way trees store carbon, causing premature defoliation and increasing their susceptibility to disease and insect attack. Even though the source of these pollutants may be at great distances from eastern Ontario, it is important to gain a better understanding of the extent to which these factors are affecting forest health in the region. Findings: Natural Resources Canada (1998) reported that south-central Ontario receives the highest rate of ground level ozone in eastern Canada and the Canadian Council of Forest Ministers (1997) reported this same area is periodically exposed to ozone concentrations above the critical level. In fact, elevated concentrations of ozone are common during the summer months when growing plants are most vulnerable to injury. Little information is currently available about the full effects of ground level ozone on eastern Ontario’s forest
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