Deforestation & Agriculture Impact

Clear Cutting

• Causes soil erosion because the roots are gone and can no longer hold the soil.
• Clear cutting leads to higher turbidity in water.
• Increased water and soil temperature because of removal of shade provided by trees.
• Increases flooding and landslides as trees are no longer there to reduce flow.
• Logging machinery compacts soil, reducing water holding capacity.
• Decreases biodiversity because the new trees are all of the same age.
• Creates lower resilience in the local environment.
• Less dead organic matter is left on the forest floor.
• It results in less filtering of air pollutants and less CO2 sequestered.

Green Revolution

• Genetically modified crops are less genetically diverse, essentially clones, so they're more susceptible to disease.

Impacts of Agriculture

• Monocropping decreases genetic diversity, making crops more prone to pests.
• Monocropping increases soil erosion because crops are harvested simultaneously, leaving the soil bare in the offseason.
• Tilling leads to erosion and less organic matter in the topsoil.
• Slash and burn agriculture burns vegetation to enrich soil with dead organic matter.
• Deforestation from slash and burn agriculture adds CO and CO2 to the atmosphere.
• Slash and burn contributes particulate matter (PM) to the air.
• Lower albedo from deforestation increases the local temperature.
• Synthetic fertilizers don't return organic matter to the soil.

Irrigation

• Furrow irrigation involves trenches.
• Drip irrigation is the most expensive method.
• Spray irrigation is moderately expensive.
• Flood irrigation can lead to waterlogged soil or rapid soil salinization.
• From most to least efficient irrigation: Drip, Spray, Furrow, Flood.
• Waterlogging prevents air from reaching roots, killing plants.
• To fix waterlogging, change irrigation style or aerate the soil.
• Agriculture uses more water than any other human activity.

Pest Control

• Herbicides are used to kill plants.
• Pesticides can lead to pesticide-resistant pests due to natural selection.
• Plants can be genetically modified to resist pests.
• Genetically modified (GM) crops are clones and can be wiped out by a single disease.

Meat Production

• Concentrated Animal Feeding Operations (CAFOs) feed animals a grain diet for efficient meat production at minimal cost.
• CAFOs use antibiotics and growth hormones, which have drawbacks.
• Animal waste from CAFOs can run off into water sources.
• CAFOs produce greenhouse gases.
• Manure lagoons are large, open storage pits for animal waste containing ammonia (N) and E. coli.
• Heavy rainfall can cause runoff from manure lagoons into nearby groundwater, leading to eutrophication.
• Free Range Grazing allows animals to graze on grass and grow at a natural rate without growth hormones or antibiotics.
• Free Range Grazing does not require corn production to feed animals.
• Free Range Grazing disperses waste naturally over land, which can fertilize the soil, avoiding manure lagoons.
• It requires more land than CAFOs, making it less efficient and more expensive.
• Free Range Grazing can lead to overgrazing.
• Rotation grazing involves moving animals around so they graze different areas, increasing production.
• Meat production is less efficient than plant production in terms of energy, land, and water use.

Impacts of Overfishing

• A fishery is a population of fish for commercial fishing.
• A fishery collapse occurs when overfishing causes a 90% population decline.
• After a collapse, the population may never recover, and the genetic diversity of the species decreases.
• Bottom trawling involves dragging a net along the bottom of the ocean.
• Bottom trawling leads to a large amount of bycatch.
• It stirs up sediment, increasing turbidity and hindering photosynthetic algae.
• Bottom trawling disturbs coral reefs.
• Overfishing can trigger a chain reaction, impacting different trophic levels.

Mining

• Overburden is the soil, vegetation, and rocks removed to access an ore deposit below.
• Surface mining includes:
  • Open pit mining, creating a large open pit.
  • Strip mining, mining in layers.
  • Mountaintop removal uses dynamite to blow off a mountaintop.
  • Placer mining involves shaking/panning out sediments in a river to find valuable materials.
• Subsurface mining becomes necessary as ore depletes near the surface, making it more dangerous and expensive.
• Subsurface mining has issues such as poor ventilation, shaft collapses, fires, and explosions.
• Vertical shafts are drilled vertically into the ground and elevators carry down workers to export ores up.
• Abandoned mines can cause rainwater to leak into the mine and mix with pyrite, forming sulfuric acid which contaminates streams and groundwater.
• This makes water more acidic.
• It also makes toxic metals more soluble in water, which can kill organisms.
• Coal mining releases methane from the rock around the coal, which is vented out of the mine to prevent explosions but continues to be released after the mine closes.
• Coal mining also releases particulate matter.
• Mine Reclamation is becoming more common.

Urbanization

• Replaces natural soils and vegetation with impervious surfaces like asphalt, which don't allow water to seep into the ground.
• Impervious surfaces lead to runoff.
• It disturbs the water cycle by decreasing groundwater recharge.
• Urbanization leads to more CO2 emissions.
• Deforestation in favor of urbanization means fewer trees to sequester carbon.
• Landfills are required to support large populations.
• Cement production is common.
• Population growth in coastal cities leads to saltwater intrusion into freshwater aquifers due to excessive groundwater withdrawal, which lowers the water table.
• Urban sprawl is the movement from an urban center to nearby suburban areas.
• There is a domino effect where neighbors leave, creating a positive feedback loop resulting in fewer residents, less taxes, less city service and businesses leave.
• A solution is to create walkable cities with public transport to keep people in urban centers.
• Mixed land use needs to be considered.

Sustainability

• Maximum Sustainable Yield is the maximum amount of a renewable resource that can be harvested without depleting it.
• It is typically about ½ of the carrying capacity.

Reducing Urban Runoff

• Impervious surfaces increase runoff.
• Runoff can collect salt or sediment from roads and contaminate or increase the water's turbidity.
• Permeable pavement decreases runoff and flooding.
• Rain gardens surround storm drains and soak up water before it reaches the drain.
• Public transit reduces the number of pollutants that leach into runoff.
• Building up rather than down reduces total impervious surface area.

Integrated Pest Management (IPM)

• IPM controls pests while using fewer pesticides.
• Biocontrol introduces natural predators to reduce pest populations.
• Crop rotation involves planting a new crop every season.
• Crop rotation prevents pests from becoming established and leads to more nutrient-rich soil.
• Intercropping involves planting multiple crops in the same area.
• Intercropping improves soil health.
• Push-pull systems use "push" plants emitting VOCs that deter pests and "pull" plants emitting chemicals that attract pests away from the harvested crop.

Sustainable Agriculture

• Contour plowing involves plowing parallel to slopes instead of down slopes to prevent runoff and water erosion.
• Contour plowing forms mini terraces.
• Terracing involves cutting flat platforms into a slope to catch water and prevent runoff.
• Perennial crops live year-round and are harvested multiple times.
• Perennial crops have longer, more established roots that prevent bare soil between harvests, preventing erosion.
• Windbreaks are trees planted to prevent wind erosion and reduce blow away soil.
• No-till farming means not tilling the soil, which leads to less soil erosion and more nutrient-rich soil.
• Strip Cropping uses alternating rows of dense and less dense plants to prevent runoff from eroding the soil of less dense plants.
• Green manure is leftover dead plant matter used as fertilizer.

This text covers the environmental consequences of clear-cutting, including soil erosion, increased water turbidity and temperature, and reduced biodiversity. It also deals with the effects of the Green Revolution and monocropping in agriculture.