Ontario Ecosystems

This is a general introduction to ecosystems as part of Ontario’s ecozones. The terms ecozone, ecoregion, ecodistrict, ecology should be understood.

The overview is divided into four parts:

i. General introduction to ecosystems which puts Ontario into a Canadian context.

ii. Specific information on terrestrial ecosystems such as forests and land use. See also Natural Ecosystems – terrestrial and aquatic. Note that managed terrestrial ecosystems that are the basis for economic activity in Ontario, such as forestry and agriculture, are in section 5.2.2c Human Settlements.

iii. Specific information on aquatic ecosystems – the Great Lakes basin.

iv. Information on toxic substances and pollutants in our ecosystems.

1. Locate Ontario’s boundaries. How many ecoregions are shown here?
2. How many of these ecoregions are in each of the categories shown in the legend?

Natural ecosystems will be affected by a changing climate.  Some of the impacts of these changes are summarized below.

Source: About Ontario, Environmental Commissioner of Ontario, (2004)

1. What is an alternative name for Hudson ecozone? Where is the 60o latitude?
2. What are the latitudes that are closest to the differences in ecozones?
3. Name the family or genus of the dominant vegetation used to identify each of the 3 ecozones’.
4. The projected climate change for Ontario, especially with twice the present CO2 concentration, shows that the vegetation present at Windsor may change its boundary northward to Sudbury. How many degrees north is this?

ACTIVITY 3 Research
1. How would trees in the present Windsor ecozone “move” northward? At what rate?
2. Which trees would take their place? Hint: This zone is also called the Carolinian zone. Check for species information.

Climate change has both beneficial and harmful effects which means good news /bad news for Ontario-presenting both opportunities and challenges. The global predictions for climate change continue to apply. Ontario predictions will be local variations of the global predictions.

There are both challenges and opportunities in our future because of increased temperature and decreased water availability. See Section 6 for future impacts. The vulnerability of ecosystems to the impacts of climate change must always be considered at the same time as the ecosystem is studied. Adaptation and mitigation should also be part of these studies so that understanding can lead to action in the context of climate change.

Implications of Climate Change on Natural Ecosystems

1. Biological productivity is expected to increase with moderate temperature increases.
2. Zoogeographical boundaries move in a changing climate.
3. Introduction of invasive species could be exacerbated.
4. Existing community structures and interactions may change.
5. A changing climate is expected to lead to reduction in some habitats.
6. Wetland vegetation communities, their functioning, and values, may change.
7. Wildlife is susceptible to climate changes.
8. Rare and endangered species may be more vulnerable.
9. Climate change and variability will also impact agriculture in the Great Lakes region, as well as forests, recreation, and tourism.

The ecozones will, with climate change, experience a change in the timing or average start and finish dates of normal seasonal events, for example, ice cover, spring flowers. Changes in the length of any season, such as the number of frost-free days or the number of low stream flow days will be also be seen as the trends noted earlier continue.

Northern Ontario human populations and ecozones will experience greater impacts of climate change.

Changes in water levels and permafrost area affect all natural and built ecosystems. These changes will also have an impact, although indirect, on southern Ontario. For example, loss of ice cover in Hudson Bay influences shipping volume and daily weather in southern Ontario. These topics are covered in other sections.

The figure below documents the family diversity in Ontario with respect to its percent tropical vegetation as shown in the legend.

Source: Don MacIver, Environment Canada

1. Compare this graph with the ecozones map of Ontario. What is the most impressive difference?
2. The legend represents the percentage of tropical climate. What is the percent range used for each color on the map? What percent for Windsor? for Sudbury? Kenora? Moosonee?
3. What is the range of degrees of latitudes shown for Ontario south to north?
4. Use the km. scale or the degrees of latitude to find the total distance in kilometers.

The tiny land mass of Southern Ontario makes accurate predictions based on global data even more difficult because of the scale. Global scale averages do not show local variations such as those due to local elevation, for example, the Niagara Escarpment and large bodies of water such as the Great Lakes.

The graph below includes data on forest biodiversity in southern Ontario, ecoregion boundary, and ozone concentrations for 1998.

Source: Don MacIver, Atmospheric Change and Biodiversity, 1997

1. Notice the area northwest of Toronto and the black bands on either side of this area.    Account for the differences in the graph shown in this region. Hint: check the contour maps.
2. What is the latitude at Windsor? At Sudbury?
3. Sites monitoring forest biodiversity and the effects of climate change are located in Southern Ontario from north to south ending at Long Point. What kind of data gradient(s) does this provide for research?    Note other sites – east to west – across Ontario have since been added. See

Temperature is considered to be the delicate trigger for the beginning of growth – especially soil temperatures. Spring growth in natural ecosystems is triggered by increase in temperature to reach the minimum required by the vegetation. Farmers choose corn to plant based on where they live, that is how many annual corn heat units their location has. Gardeners use hardiness zone maps to choose their plants and seeds.

The figure below shows southern Ontario as represented by Corn Heat Units (CHU). CHU are in degrees Celsius. This accumulated value is calculated using the following conditions:

1. Start-up of corn growing season: the mean daily air temperature is> 12.8 oC for three consecutive days during the period May 11 to July 31.
2. End of the season: the first occurrence when the minimum daily air temperature drops below -2.0 oC during the period August 1 to October 15.

Southern Ontario Average Annual Corn Heat Units (CHU)

Source: Watson and MacIver (1995)

1. This is the southernmost part of Ontario and of Canada. What is the range of latitude shown?
2. What is the range in CHU on this map? The number of CHU per color on the legend?
3. Check the area shown against the forest cover map and CHU map for agricultural use later in this section. Does this area go north beyond the 2900CHU line shown there?
4. Check with the map showing loss of original wetland area. What does correlating these maps explain?

ACTIVITY 7 Research

1.  Check the hardiness zone map used by gardeners and foresters for correlation.
2. Check climate change impacts: agriculture, natural vegetation, and economic implications.

Subtle warming of one or two degrees changes the land use as documented in the next graphs. The graph below plots forest family data from the southern Ontario forest biodiversity monitoring sites against growing degree days (GDD).

Source: MacIver and Auld, Environment Canada, 2000

1. What kind of mathematical relationship does this show?
2. How many tree families would be found in Shelburne, Ontario?
3. What factor(s) besides heat units must be considered at Shelbourne?
4. Why can the authors entitle this graph Climate and Biodiversity Change?

ACTIVITY 9 Research
Compare ecological studies graphing vegetation zones- from the Equator to the poles and from sea level to high altitudes.

Land use in Ontario
Available heat acts as a powerful trigger of growth in the natural world. The first inhabitants in Ontario, after the glaciers retreated about 12, 000 years ago, were aware that the success of their plantings depended on the warmth of the area. Archeological records show that corn, squash, and beans were planted together. The “three sisters”, as they were called, benefited from growing together in the same planting for other reasons.

ACTIVITY 10 Research
1. Why were the “three sisters” good choices to grow together?
2. What else was added in many cases to the hole in which these three were planted?
3. What adaptations to planting in Ontario today are equivalent?

Today’s farmers and gardeners are very aware of corn heat units as they choose crops to plant. Seed companies test for this factor as well as GDD (Growing Degree Days). The map below shows the contour lines for the threshold CHU and the remnants of forest cover. Note that the darker areas show the forest remnants, while the lighter areas indicate agricultural lands.

Source: Auld and MacIver, Environment Canada, 2000

1. The solid block of forest is found on the Six Nation reserve south of Brantford.    The phrase “seven generations” is often used in decision making by the community. What does this mean with respect to this map?
2. Account for the 2 other very dark red sites. Hint: Check the Ontario Parks map.
3. What conditions, besides available heat, make southwestern Ontario the best land for Ontario agriculture?

ACTIVITY 12 Research
Why can it be said that the rows of red dots above the 3200 CHU contour reflect the settlement of Ontario? What does ISQ represent?

In order to better use the land in Ontario’s short growing season, agricultural practices have shown that better drainage allows the soil to dry earlier and faster. This allows the machinery on the land sooner in the planting season without being mired in mud.

Farmers in southern Ontario have invested heavily in draining wetlands and /or installing drainage tile (a system of slotted, ribbed piping which allows water to seep in and be carried away) to get on the land sooner for planting. The map below reflects these practices.

Source: MacIver and Auld, Environment Canada, 2000

1. Compare this contour line for 2800 CHU against a contour map of Ontario. Similarities? Differences?
2. Compare this map against a map of Ontario showing soil types. Similarities?
3. What adaptive measures should be undertaken to reduce vulnerability to the impacts of climate change?

ACTIVITY 14 Research
1. What does the legend reflect in terms of human settlement in Ontario?

See Section 5.2.2b, Aquatic, terrestrial and modified ecosystems of agriculture and forestry.

Toxic substances in our ecosystems

23,000 substances currently in use are under review to determine if they are toxic or capable of becoming toxic. Change in emissions of toxic substances varies. In 1988 there were 9 substances. In 2002 there were 52. Toxic substances come from many industrial and household uses. A substance is toxic if enters the environment in a quantity that has or may have a harmful effect on the environment or the health of endangered species, aquatic life, and human health.

Bioaccumulation and biomagnification occur when some substances, like mercury and DDT, are passed along a food chain. Each link in the food chain accumulates or concentrates the substance during its lifetime. When eaten, the concentration is magnified at each level in the food chain. Top carnivores thus receive the greatest concentration of a toxic substance from the food chain. Check out the story of the peregrine falcon and DDT.

Analysis of each substance must be made before it is defined as a toxic substance by the Canadian Environmental Protection Act 1999(CEPA). The National Pollutant Release Inventory (NPRI) provides information on releases and transfers of air, water, and land pollutants from large industrial and commercial sources – if the facilities meet the reporting criteria. Exemptions are made for certain sectors and small scale releases.

There are complex risks due to the number of substances and their possible interactions with each other and with the environment. Concentrations found in wildlife, such as ducks, fish and polar bears, are used as early warning signs for effects on ecosystems and human health.

The challenge is for government and industrial communities to work together. They need to have enough information to analyze and limit the integrated risks of new substances and develop preventive or healthy alternative measures. Individual consumers must also read labels and be aware of their choices.

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