Lecture 7

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Environmental Science
Environmental Science 1021F/G
Marnie Branfireun

ES1021G Lecture 7: February 15, 2011 Renewable Resources Overview: •Characteristics of renewable resources •Major classes of renewable resources •Resource degradation: overharvesting •Characteristics of renewable resources •Major classes of renewable resources •Resource degradation: overharvesting Characteristics: •Renewable resources have the ability to regenerate after they are harvested •Potentially, they can be harvested forever without depletion •The key is to not harvest them faster than their regeneration, or to otherwise mismanage them Important Note: Reliance on renewable resources is a core attribute of a sustainable economy; one that can run forever without depleting its essential base of natural resources. Major kinds of renewable resources: •Fresh water: recharged through the hydrological cycle •Agricultural resources: crops and site capability •Forest resources: timber •Hunted animals: whales, seals, fish, deer, waterfowl •Sunlight (in its various manifestations): (see Chapter 13) •Passive solar •Wind •Flowing water •Biomass •Photovoltaics Freshwater •Groundwater •Occurs in aquifers – underground reservoirs •Used by many rural people and by urban utilities without access to abundant river flow or lakes •Surface water •Occurs in lakes, rivers and wetlands •In general, freshwater is abundant in Canada •Exception: some arid regions •Water quality is sometimes poor. This may be due to natural salts, eutrophication, or contamination by fecal pathogens from livestock Agricultural resources 1of 3 ES1021G Lecture 7: February 15, 2011 •Site capability – influences crop productivity •Climatic conditions are important •Tilth – related to soil structure and organic content •Plant Crops •Key grains: wheat, oats, barley, maize •Others: soybean, canola, potato •Forage crops for livestock •Animal crops •Key species: cow, sheep, pig, chicken, turkey •Most are raised intensively on ‘factory farms’ Forest Resources •Forest area – only ½ of global forests are left •Will likely be again halved in ~50 years •Deforestation – mostly occurs in tropical countries •Timber harvesting •About 1-million ha/year in Canada •95% by clear-cutting (in 2006) •Wood used to manufacture lumber or paper, or as fuel •Forest management •39% of harvested area planted with seedlings; the rest is natural regeneration •Plantations (tree farms) are most intensively managed Fish Resources •Marine fisheries – most of the world’s most important fisheries are now badly degraded •Also in Canada – such as badly depleted stocks of cod in the Atlantic, salmon in the Pacific •The damage is mostly caused by over-fishing; ‘mining’ the fish •Aquaculture is
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