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GEOG 205 Lecture Notes - Agroforestry, Evapotranspiration, Permafrost


Department
Geography
Course Code
GEOG 205
Professor
Gail Chmura

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March 27th, 2013: Land Use (Guest Lecturer)
what is land use? what do we use land for?
o transportation
o agriculture
o raising livestock
o residential, commercial, industrial
o parks & conservation
o recreation
o extractive activities logging
amount of land for crops only is about 12% 36% for crops + pasture
amount of land for conservation areas is about 11-12%
extractive activities (logging, mining, etc.) areas have no estimation of land use take relatively
small amount of land but the impacts are wide, so it’s hard to measure in terms of area
urban areas take up only 3% of global land 50% of people on earth live in urban areas
global land use change over time questions to consider after watching the video
o what type of major historical events seem to have an impact on land use?
industrial revolution
colonization
war
political situations
o name one change that surprised you
first land uses were agriculture there is evidence of farming fields that were abandoned over
600 years ago in South America
around 1850, the conversion from natural ecosystems to cropland really took off
we have essentially converted all arable land in North America to cropland
land use transitions show that once land use usually comes at the expense of another over time
o natural ecosystem frontier clearings subsistence agriculture & small-scale farms
intensive agriculture or urban areas or protected/recreational lands
o this is the kind of transition that happened in North America and that is happening in Latin
America & the Tropics now
agriculture covers 2.5 billion hectares (area size of South America) are currently used for crops
(12% of planet’s free land)
agricultural plot planning is different everywhere in Minnesota plots are rectangular, Kansas
uses circles, Thailand uses thin strips of land that back onto a canal, etc.
grasslands have rich soils that are good for growing crops & they have the right amount of
precipitation, so they are typically the “bread baskets” of the world
“meat baskets” of the world are in deserts and rainforests
roughly 55% of the world was covered by forest originally now it is 30% of global land area
o we sill have over 50% of original forest cover
o we don’t have much temperate forest at this point
o forests have been cleared from densely populated areas Asia
o roughly 25% of previously forested global land area has been transformed
o now, most changes are happening in tropical rainforests of Southern America
Brazil has the largest annual net loss in forest area from 2000-2005 can clear entirely in 154
years in continue
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