A practice in which only some of the trees in an area are cut down and harvested
This prevents soil erosion because the remaining trees are still able to hold the soil down and provide shade to the earth
5.3 The Green Revolution
The Green Revolution
A period where technology upgrades and a transition to larger-scale farms allowed for increased crop yields, profits, and efficiency
Farming became more efficient because farmers began using mechanized tools, pesticides/fertilizers, and other modernized technology
The increased crop yields allowed food production to massively increase
However, the new tools put into practice are much more harmful to the environment
Contamination, loss of biodiversity, and usage of fossil fuels all cause more damage
Irrigation
Modern irrigation systems deplete groundwater and aquifers
The increased presence of water also means that the dissolved salts in the irrigated water may be carried to the roots of plants, which can cause soil salinization
Used by farmers to eliminate pests in the hopes that crop yields will go up (since pests are no longer enacting crop damage)
Pests may adapt over time to become resistant to existing pesticides, which would mean that new pesticides would be needed
GMOs (genetically modified organisms)
Pro: genetically modified organisms can be selectively bred to possess pest-resistant traits
Con: if all of the crops in a field are genetically identical as a result of the GMO process, then the biodiversity will be lowered, which reduces the chances that some of the population will survive potential disasters/infections
Animals roam and graze on grass during their life cycles
Generally free from chemicals/antibiotics
Requires more land, tends to produce more expensive meat
CAFOs (concentrated animal feeding operations)
Animals are crowded and are fed grains/feed
Organic waste from CAFOs can lead to contamination of local waters
Feedlots tend to be less expensive to run, so the meat is less expensive
Overgrazing
Result of too much grazing in a field of land
Causes loss of vegetation and therefore leads to soil erosion
May also lead to desertification
Energy efficiency
Meat tends to be energy inefficient because the effort required to produce meat includes the energy spent on growing the grass, producing food for the animals, and housing the animals
5.8 Impacts of Overfishing
Overfishing
When too many people fish at a higher rate than the habitat can produce fish, the amount of fish in the habitat will be depleted
This may lead to the scarcity of certain fish species
This also lowers biodiversity in aquatic ecosystems
People who rely on fishing as a source of income/commerce are hurt
The type of mining that is performed to harvest ore close to the surface
With mountaintop removal mining, explosives are used to take out massive chunks of land at once
This is especially harmful to the environment because it indiscriminately damages an entire range of land
Strip mining involves cutting “strips” of land and mining each strip separately
Open pit mining involves cutting a large pit into the ground and mining from it
Placer mining involves exacting minerals from stream bed deposits
Subsurface mining
This type of mining is done in order to reach ore that is buried deeper beneath the ground level
This strategy poses a lot of health risks for those mining underground
Acid mine drainage
When rainwater leeches into abandoned mining sites, the water and oxygen present will combine with the pyrite exposed from mining, creating sulfuric acid
This contaminated water may run off and harm local aquatic life as well
5.10 Impacts of Urbanization
Urbanization
The process of converting natural land into land prepared for cities
The “ground” created for cities (such as cement/concrete) is often impervious, meaning that it doesn’t allow water to travel through it
This leads to runoff issues because water cannot successfully penetrate
Runoff water can also accumulate pollutants as it travels over land
Impervious surfaces constructed above aquifers prevent the aquifers from recharging because groundwater cannot make it from the surface to the aquifer
Saltwater intrusion
When coastal cities deplete the freshwater available near the coast for human purposes, the saltwater surrounding the freshwater will be forced to fill the “space” left behind in the freshwater, which contaminates freshwater with salt
Urban sprawl
The process by which people move away from the nucleus of a city and instead branch out into nearby suburban expansions
The increased gas usage from suburban residents driving to work, as well as the land that must be given up for suburban construction, both display how this process isn’t good for the environment
A possible solution would be to restrict how far land can be developed when compared to the starting point of a city
5.11 Ecological Footprints
Ecological footprint
The measure of how much land a person/group of people uses
Land is required for housing, the harvesting of materials, food/electricity/energy generation, etc.
This can also be measured by the amount of “Earths” that would be required to sustain the current levels of resource consumption
The amount of carbon dioxide, measured in tons, that a person/group of people produces annually
This includes the carbon dioxide used when creating goods/materials for that person/those people
5.12 Introduction to Sustainability
Sustainability
The use of resources that uses resources in a way that prevents depletion of the resources that future generations would need/use
Biological diversity, food production, average global surface temperatures, carbon dioxide concentrations, human population numbers, and resource depletion can be used to measure how sustainable human behavior is
Sustainable yield
The amount of renewable resource that can be taken without reducing the available supply
Crop rotation
This farming practice is more sustainable because the growth of only one type of crop would severely deplete the specific resources that that crop needs
Instead, crop rotation allows soil nutrients to be used at more tolerable levels
This system prevents overgrazing by rotating animals across different pastures
Pastures have time to fully grow back in between waves of animal grazing
Prevents the soil erosion issues that arise from overgrazed land
5.13 Methods to Reduce Urban Runoff
Urban runoff
A result of urbanization
When water cannot drain properly into the soil due to the presence of concrete, the water instead becomes “runoff” and picks up pollutants as it travels along concrete surfaces until it finally finds a draining spot
If it drains into a body of water, then that water will become heavily polluted
Constructing/expanding a city vertically instead of allowing for urban sprawl reduces the area of concrete present in a larger location, which minimizes the amount of water runoff that occurs
Permeable pavement
This type of pavement reduces urban runoff issues because its design allows water to seep into/travel through the pavement layer and therefore successfully recharge groundwater without picking up surface pollutants
A “garden” of plants that is built into a depression in the surface
This collects rainwater and can hold it until the water is filtered by the garden, then seeps into the ground
5.14 Integrated Pest Management
IPM (integrated pest management)
A more environmentally friendly approach to combating pests
Although it may not eliminate the use of pesticides entirely, it does identify the levels of pest damage that can be tolerated before chemicals become necessary
Resistant varieties
Varieties of a crop that are resistant to pests are selectively bred so that future crops will also be pest-resistant
Beneficial insects
Insects that prey on crop-killing pests are released into the crop area
This cuts down on the number of pests present
Microbial pesticides
Protozoans/bacteria/etc that effectively harm pests
The cultivation of aquatic organisms in a controlled aquatic environment for commercial/recreational/public purposes
Pros: Raising fish in these sorts of enclosures requires little energy/small amounts of water
Cons: Aquaculture can contaminate surrounding water due to waste (especially if the fish were fed antibiotics), aquaculture fish may escape and compete/breed with wild fish, and the density of fish in enclosures means that diseases spread much more quickly and are more devastating
Diseases can also be transferred to wild fish.
If fish escape the aquaculture enclosure, then those fish could introduce GMOs or non-native genes into the surrounding ecosystem
5.17 Sustainable Forestry
Sustainable forestry
Forestry practices that minimize the amount of damage done to the ecosystem
Humans may also help the ecosystem/tree population by selectively removing trees that are diseased before those diseases can spread.
Reforestation
The replanting of trees in areas where previous trees had been cut down
Selective cutting
Only cutting down some of the trees in an area instead of fully deforesting the entire area.
When dead biomass (dead trees/plants) is burned up in a small, controlled manner, future forest fires will not be able to spread as easily because they won’t have as much dead biomass to catch onto/spread from
The burning of dead biomass also eliminates pests/diseases that may have been present in the decaying trees/plants.
Nutrients in the dead biomass are also released back into the environment.
