Unit 5 Test Part 3 Midterm Review Flashcards
Sustainable grazing requires tradeoffs
Overgrazing happens when too many grazers are allowed to use a pasture
It can result in plant death, which in turn makes the fields vulnerable to erosions
People throw fertilizer on it, but temporary solution, it washes off
Over fertilization of pasture is another issues
Rotational grazing eliminates these issues and allows for sustainable pasture - but this is time consuming and expensive
Desertification
“Overgrazing can cause desertification. Desertification is the degradation of low precipitation regions toward being increasingly arid until they become deserts.”
Other causes too
Salinization
Slash and Burn
Over Logging
Depletion of Water
Result in increased fertilizer
Loss of productivity
Carbon Footprints of Different Types of Food
“Meat production is less efficient than agriculture; it takes approximately 20 times more land to produce the same amount of calories from meat as from plants.”
Big beef - an industry that helps disconnect food from nature
Monopoly by four companies in meat processing plants
This harms economic mobility in rural America, and reinforces the feedlot method beef production so that processing plants can run at full capacity
Ecological Footprints
Ecological footprints compare resource demands and waste production required for an individual or a society.
Urbanization
Urbanization
As people move into larger cities and out of countryside (fewer farm jobs exist) what effect does this have on the environment?
Two ways to look at this
Cities take massive environmental toll
Cities are more sustainable than low density ‘sprawl’
BUT cities almost always include extensive sprawl!
urbanization increase amount of carbon dioxide in atmosphere through burning of fossil fuels and landfills
Urban Sprawl
Uncontrolled rapid expansion of cities into surrounded landscape - car dependent culture, where things are spatially separated and housing densities are much lower
Higher water use
Higher electricity use
Higher car use
Higher land use
Urban sprawl i s the change in popular distribution form high population density areas t o low density suburbs that spread into rural lands, leading to potential environmental problems
Impervious surfaces
human-made structures that do not absorb water, water cannot reach the soil, leads to flooding and reduced groundwater recharge
Methods to increase water infiltration
replacing traditional pavement with permeable pavement, planting trees, increased use of public transportation and building up, not out
Runoff - huge issues in cities due to impermeable surfaces; permeable pavement does exist and helps significantly
Urban street trees help improve air quality, reduce runoff, and give people mental health benefits
Urbanization can lead to depletion of resources and saltwater intrusion in the hydrologic cycle
Saltwater is denser than freshwater - so is found below in groundwater reserves
As urbanization (and agriculture) rapidly deplete these wells of groundwater, salty water below the wells can begin to rise, ‘intruding’ into the freshwater supply
250 mg/L is considered unsafe in drinking water, and standards typically well below this - so it doesn’t take much salt to render a well useless for drinking
Urban Heat Island Effect
Blacktop and lack of evapotranspiration
In an urban area it is hotter than surrounding areas
Trees provide good evaporative cooling effect, they are leaking water and evaporation takes away heat, helping to cool and mediate temperatures
In urban areas there is a lot of dark surface, absorbs heat, which causes it to be hotter, while grass and other surfaces don’t absorb heat as much which mediates temperature in non urban areas
Sustainable yield
amount of a renewable resource that can be taken without reducing the available supply
MSY = Maximum Sustainable Yield
Increases economic growth while maintaining viability of populations
Don’t want to cut population back beyond where growth rate is at its highest, take about half
