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GEOG 205 Lecture Notes - Maple Sugar, Acer Saccharum, Crop Yield

4 pages95 viewsWinter 2013

Course Code
GEOG 205
Gail Chmura

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April 10th, 2013
you can make your midterm mark worth 10% and the final worth 45%... but you
have to email Drew on the 22nd… (April 22nd @ 10 am)
BUT the final is hard (and cumulative) … similar to the midterm
final consists of: 4 essay questions (40 points); 10 short answer (20 points); 40
multiple choice/true false questions (each other 1 point, 40 points total)
impacts on agriculture (food, fibre, forests around world affects growth)
o elevated CO2
o higher temperatures
o altered precipitation & transpiration regimes
o increased frequency of extreme events
o modified weed, pest & pathogen pressure
what we will talk about:
o increasing levels of carbon dioxide
o availability of water
o changes in temperature
o possible increases in pests
CO2 increases in plants
o referred to as CO2 fertilization effect there is more carbon dioxide in the
atmosphere so plants uptake it easier and therefore grow faster
o it is plant food
o the actual effects are an area of intense complexity, study & uncertainty
o C3 plants: wheat, rice and soya bean show the largest increase
o maize, sorghum, sugar cane, millet & many pasture/forage grasses show
lesser increase
o the difference between these plants are the photosynthesis reactions that
take place, they are slightly different, specifically in terms of enzymes
o including idea of water & nutrient availability, experiments show increases
under unstressed conditions in range of 10-25% for C3
o this doesn’t mitigate climate change because eventually the plants became
saturated in carbon dioxide, so they cannot uptake anymore this is
because there aren’t enough nutrients in the soil such as nitrogen
o impacts are unequal
o there aren’t dramatic decreases regionally in bread baskets, but do see
regional variations with local winners & losers
o see further stress put on areas that already struggle with being self-
sustaining with regard to agricultural yield
o places may experience more extremes
o regions in Southeast Asia which rely on unregulated rivers might be more
susceptible to change
o temperature is the deciding factor here
for cereal crops, potential yields projected to increase for small
increases in temperature but decrease for larger temperature rises
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