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GEOG 205 (26)
Lecture

April 10th

4 Pages
95 Views

Department
Geography
Course Code
GEOG 205
Professor
Gail Chmura

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Description
th April 10 , 2013  you can make your midterm mark worth 10% and the final worth 45%... but you nd nd have to email Drew on the 22 … (April 22 @ 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  CO 2ncreases in plants o referred to as C2 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  in most tropical & subtropical regions, potential yields are projected to decrease for most increases in temperature  due to crops being near maximum temperature tolerance (worse with decreased precipitation)  BUT globally greater than 3C increase could mean decline in both places  relationship to pests o weeds, pests & fungi thrive under warmer temperature, wetter climates & increased CO2 o warm weather pests can star breeding sooner & have more hatches; expand their ranges o there is a disruption of synchrony between pests & predators due to this o increased frequency of pest outbreaks & upheavals which are previously at equilibrium  USA sugar maple o 70% of tree species showing tree range migration in USA o maple trees that produce maple sugar will be moving southward  great Spanish olive migration o Spain produces 46% of world’s olive oil, increased from 28% in 2002 o gain came at expense of Greece & Italy where olives died due to high temperatures and lack of water  baseline for agriculture o effects on agriculture can depend greatly on a
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