Effects of Climate Warming on Lakes of the Central Boreal Forest

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Effects of Climate Warming on Lakes of the
Central Boreal Forest

• Schindler et al. 1990

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Major Question

• How climate warming (or greenhouse warming)
  affects the physiological, chemical, and
  biological processes in the Experimental Lakes
  Area in northwestern Ontario (specifically Lake
  239 Reference Basin).

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Main Variables/Parameters Discussed

• Air and lake temperatures.
• Precipitation.
• Water renewal.
• Nutrient and chemical concentrations.
• Water flow.
• Forest fires.
• Wind velocity and exposure.

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Continued.

• Water clarity and sun exposure (relate to Secchi
  depths).
• Thermocline location within water column.
• Duration of ice-free season.
• Phytoplankton population and diversity.

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Theory

• Models have predicted that increases in
  greenhouse warming would increase air temperature
  and reduce soil moisture significantly in North
  America.
• These effects should be more pronounced at 48-52
  degrees N and 90-100 degrees W, which
  approximates northwestern Ontario.

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Continued

• Naturally, boreal systems in this region are
  arid, warm, and contain sandy soils with small
  water storages thus, are prone to forest fires
  during minor droughts because of rapid soil
  depletion.
• SO!!! If the forecasts are correct, increased
  climate warming should severely affect the boreal
  systems in northwestern Ontario!!

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What Did They Do??

• Starting from 1969-1971, continuous records of
  weather, water chemistry (for lakes and the
  streams connected), and hydrology were gathered
  and analyzed at the Experimental Lakes Area (_at_
  Lake 239) near the predicted maximum summer
  greenhouse effect.
• Methods used for measuring the variables
  significant to the experiment were CONSISTENT!!

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Results

• Ultimately, the mean annual air temperature
  increased by about 2 degrees Celsius!!

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Results

• From increasing air temperatures, lake
  temperature increased and so did the duration of
  the ice-free season (as a result of more heat
  content in the water).

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Results

• Mean annual precipitation decreased and with warm
  air temperatures, volume of runoff decreased due
  to more evaporation.
• And with little runoff, water renewal decreased
  as well.

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Results

• Decreases in water renewal concentrated chemical
  dilutes, including N.
• But Phosphorus was not statistically different
  during the record of the experiment.

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Results

• Since there were high frequencies of forest
  fires, the water was clearer and the lake was
  more exposed to wind and solar energy.

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Results

• These in turn allowed for the thermoclines in the
  lakes to deepen.

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Results

• With increasing temperature and nutrient
  concentration, standing crop of phytoplankton
  increased, but phytoplankton diversity only
  slightly increased.

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How do these changes impact living organisms??

• Cold, stenothermic (live within a narrow range of
  temperatures) organisms such as lake trout are
  unable to survive under these conditions.
• These organisms need cold, well-oxygenated
  environments such as in the deep hypolimnion.
• But with thermoclines deepening and less cool
  waters present, they cannot survive.
• Thus, their distributions are more confined to
  un-stratified lakes in the Sub-Arctic and in the
  hypolimnion of southern stratified lakes.

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Conclusion

• Does increasing climate warming have a severe
  effect on the boreal systems in northwestern
  Ontario???
• HECK YEAH!!!!!!!

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Relation to other papers

• Climate change decreases aquatic ecosystem
  productivity of Lake Tanganyika, Africa.
  (OReilly et al. 2003).
• Wind activity in Lake Tanganyika actually
  decreased.different from the case in Ontario
  where forest fires allowed for higher wind
  velocities because of increase exposure to the
  wind by the lakes.

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Why is my paper important?

• Climate warming is causing severe changes to
  biotic systems, and therefore, is disrupting the
  habitats for species that live there.species
  which cannot survive there must either leave or
  ultimately go extinct.
• Furthermore, climate warming is a global issue
  completely it is not confined to just
  northwestern Ontario.
• In fact, I see it here in Vancouver, Williams
  Lake, and the Thompson Okanogan (long droughts in
  summer, shorter severe winters)!!

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Ask Jon!!!!