Rucete ✏ AP Environmental Science In a Nutshell
5. Land and Water Use
This unit explores how humans use land and water resources, the environmental impacts of agriculture, mining, urbanization, and forestry, and methods for achieving sustainability. Key topics include the Tragedy of the Commons, agricultural revolutions, irrigation, aquaculture, and sustainable practices in pest management and land use.
5.1 The Tragedy of the Commons
Concept
• Coined by Garrett Hardin in 1968, it refers to the overuse of shared environmental resources by individuals acting in self-interest.
• Resources like air, water, forests, and oceans are “commons” vulnerable to depletion.
Examples
• Overfishing, air pollution, groundwater depletion, habitat destruction, and poaching.
Limitations of Solutions
• Privatizing land fragments policies and standards.
• Economic incentives often favor short-term gains over long-term sustainability.
• Some commons, like oceans and air, are difficult to regulate due to lack of ownership.
5.2 Clearcutting
Definition
• A forestry method where all trees in an area are cut simultaneously.
Environmental Impacts
• Habitat loss and reduced biodiversity.
• Increases temperature and dryness at ground level.
• Increases runoff and soil erosion.
• Reduces carbon sinks, contributing to climate change.
• Alters forest microclimates and disrupts food webs.
Edge Effects
• Clearcutting creates forest edges that alter environmental conditions and degrade habitat quality.
Deforestation Impacts
• Increases erosion, changes local climates, reduces biodiversity, and fragments ecosystems.
• Contributes to CO₂ emissions and endangers migratory species.
5.3 The Agricultural and Green Revolutions
Agricultural Revolution
• Began ~10,000 years ago; humans transitioned from hunting/gathering to farming.
• Led to permanent settlements and food surpluses.
Green Revolution (1940s–1960s)
• Rapid increase in agricultural productivity through technology, synthetic fertilizers, pesticides, and irrigation.
• Introduced genetically modified and high-yield crop varieties.
• Significantly reduced hunger but introduced environmental concerns.
Positive Impacts
• Increased food supply and crop yields.
• Reduced global famine rates.
• Enabled population growth and urban development.
Negative Impacts
• Soil degradation, water overuse, and pollution from fertilizer and pesticide runoff.
• Loss of crop genetic diversity.
• Dependence on fossil fuels and large-scale monocultures.
5.4 Agricultural Practices
Tilling
• Mechanically turning soil before planting; reduces compaction and weeds but increases erosion and CO₂ release.
Slash-and-Burn
• Forests are cut and burned to clear land and release nutrients into soil.
• Often unsustainable: soil nutrients are quickly depleted, leading to further deforestation.
Fertilizers
• Organic: made from plant/animal waste (e.g., manure, compost); slower release of nutrients, improves soil structure.
• Synthetic: industrially made; fast-acting but can cause runoff, algal blooms, and aquatic dead zones.
Irrigation Methods
• Furrow: ditches between rows; cheap but inefficient (33% effective).
• Flood: entire field flooded; moderately efficient (~80%).
• Spray: water sprayed through nozzles; more precise (75–95%) but energy-intensive.
• Drip: water drips slowly near roots; most efficient (95%) but expensive and clogs easily.
5.5 Irrigation Methods (continued)
Waterlogging
• Over-irrigation can saturate soil, filling air spaces and suffocating roots.
• Leads to reduced productivity and increased soil salinity.
Salinization
• Accumulation of salts in soil from evaporation and poor drainage.
• Reduces crop growth and may require soil flushing or fallowing to recover.
5.6 Pest Control Methods
Pesticides
• Chemicals used to kill or control pests (insects, weeds, fungi).
• Insecticides: kill insects; Herbicides: kill weeds; Fungicides: kill fungi.
• Effective short-term but can cause resistance, non-target species death, and pollution.
Biological Pest Control
• Uses natural predators, parasites, or pathogens to manage pests.
• Example: ladybugs to control aphids, Bacillus thuringiensis (Bt) bacteria for larvae.
• Reduces chemical use, but risks introducing invasive control species.
Integrated Pest Management (IPM)
• Combines biological, physical, and limited chemical methods to manage pests.
• Emphasizes prevention, monitoring, and ecosystem balance.
• Often uses crop rotation, habitat manipulation, and resistant crop varieties.
Benefits of IPM
• Reduces pesticide resistance and environmental damage.
• Maintains crop yield and biodiversity.
• Promotes long-term sustainability and cost savings.
5.7 Meat Production Methods
Concentrated Animal Feeding Operations (CAFOs)
• Densely packed, industrial livestock facilities.
• Animals (cattle, pigs, poultry) are fed grain-based diets and often given antibiotics and hormones.
• Pros: high efficiency and low-cost meat production.
• Cons: large waste output, antibiotic resistance, water and air pollution, animal welfare concerns.
Free-Range Grazing
• Animals graze on open land, foraging naturally.
• Benefits: less antibiotic use, natural diets, manure distributes nutrients on land.
• Drawbacks: requires more land, higher cost, and risk of overgrazing.
Overgrazing
• Occurs when livestock exceed the land’s carrying capacity.
• Leads to soil compaction, erosion, reduced vegetation, and desertification.
• Solutions: rotational grazing, reducing herd size, reseeding pastures.
Meat Production and the Environment
• Produces more greenhouse gases (especially methane from cows) than plant-based diets.
• Requires more water, land, and energy than growing crops.
• Dietary shifts to plant-based proteins can reduce environmental impacts.
5.8 Impacts of Overfishing
Trends in Global Fishing
• Demand for seafood has risen dramatically, depleting wild fish stocks.
• Technologies like sonar, large trawlers, and longlines increase harvest efficiency but also bycatch.
Environmental Impacts
• Disrupts food chains and ecosystem balance.
• Reduces biodiversity and causes economic losses for coastal communities.
• Damages habitats like coral reefs and sea floors (e.g., bottom trawling).
Solutions
• Marine reserves, catch limits, no-take zones, and aquaculture.
• International cooperation and enforcement are crucial for success.
5.9 Impacts of Mining
Environmental Consequences
• Deforestation, habitat destruction, and soil erosion.
• Contamination of soil and water with heavy metals, acids, and toxic runoff.
• Acid mine drainage (AMD): sulfuric acid produced from exposed rock mixes with water, harming aquatic life.
Types of Mining
• Surface Mining: includes strip mining, open-pit mining, and mountaintop removal.
• Subsurface Mining: underground tunnels used to extract minerals with less surface damage but higher worker risk.
Tailings and Waste
• Mining waste (tailings) often stored in ponds; can leak or collapse, polluting water and soil.
Human Health Impacts
• Exposure to dust, heavy metals, and toxic chemicals can lead to respiratory illness, cancer, and neurological damage.
• Subsurface mining increases risk of cave-ins and lung disease (e.g., black lung).
Restoration and Regulation
• Reclamation restores mined land with vegetation and contouring.
• U.S. Surface Mining Control and Reclamation Act (SMCRA) requires post-mining restoration.
5.10 Urbanization
Trends
• Over 55% of the world’s population lives in cities; expected to reach 68% by 2050.
• Rapid growth in developing nations leads to informal settlements and strain on infrastructure.
Environmental Impacts
• Heat islands: urban areas become warmer than surrounding rural areas due to concrete and reduced vegetation.
• Air pollution from transportation and industry.
• Water pollution from runoff, sewage, and waste disposal.
Resource Use
• Urban areas consume vast amounts of energy, food, and water.
• Impervious surfaces prevent water infiltration, increasing runoff and flooding.
Sustainable Urban Planning
• Smart growth, green roofs, public transit, zoning regulations, and urban greenspaces reduce impacts.
5.11 Ecological Footprints
Definition
• An ecological footprint measures the land and water area required to provide resources and absorb waste for a population.
• Expressed in global hectares (gha) per person.
• Helps compare human resource demand with Earth's biocapacity.
Major Footprint Components
• Food production and consumption
• Energy use (electricity, fossil fuels)
• Transportation and infrastructure
• Waste generation and carbon emissions
Ways to Reduce Footprints
• Reduce meat consumption
• Use renewable energy
• Recycle and compost
• Use public transportation or walk/bike
• Practice energy and water conservation
5.12 Sustainability
Definition
• Sustainability means meeting current needs without compromising future generations’ ability to meet theirs.
• Involves environmental, social, and economic balance (the triple bottom line).
Indicators of Sustainability
• Biodiversity, ecological footprints, soil and water quality, resource depletion rates, human development index (HDI).
Sustainable Practices
• Forest certification, sustainable agriculture, green buildings, renewable energy, and resource-efficient design.
• Community involvement, education, and long-term planning are crucial.
5.13 Methods to Reduce Urban Runoff
Problem
• Impervious surfaces (pavement, rooftops) prevent water from soaking into soil.
• Increases runoff, flooding, erosion, and water pollution.
Reduction Strategies
• Permeable pavement, green roofs, rain gardens, and vegetated swales.
• Planting trees and restoring wetlands.
• Installing rain barrels and limiting development in flood-prone areas.
5.14 Integrated Pest Management (IPM)
Definition
• IPM is a sustainable approach to managing pests by combining multiple control strategies to minimize environmental and health risks.
Techniques
• Biological control (natural predators or parasites)
• Crop rotation and intercropping
• Physical barriers or traps
• Targeted pesticide use only when necessary
Benefits
• Reduces chemical pesticide use
• Lowers resistance development in pests
• Protects non-target species and biodiversity
5.15 Sustainable Agriculture
Goals
• Produce food while conserving resources, soil fertility, and ecosystem health over the long term.
Practices
• Crop rotation and polyculture
• Agroforestry and contour plowing
• Conservation tillage and cover crops
• Integrated pest and nutrient management
Benefits
• Increases resilience, reduces erosion, and improves water retention.
• Minimizes synthetic input dependency and enhances biodiversity.
5.16 IPM vs. Chemical Pesticide Use
Chemical Pesticide Use
• Fast-acting and effective but can cause resistance and non-target harm.
• Leads to pollution and potential human health effects.
IPM Comparison
• Slower and more labor-intensive but more sustainable long-term.
• Minimizes environmental impact and promotes ecological balance.
5.17 CAFOs vs. Free-Range Grazing
CAFOs
• High density, low cost, high emissions, high antibiotic use.
• Generates concentrated waste and pollution.
Free-Range Grazing
• Lower emissions, more humane, less antibiotic use.
• Requires more land and cost, but promotes soil health and animal welfare.
5.18 Fishing Techniques
Techniques
• Long-line fishing, purse seining, and bottom trawling increase harvest but cause bycatch and habitat destruction.
Solutions
• Gear modifications, marine protected areas, quotas, and international cooperation reduce impacts.
In a Nutshell
Human use of land and water resources—through agriculture, forestry, mining, and urbanization—has profound environmental consequences. Sustainable practices like IPM, crop rotation, aquaculture, and conservation-focused urban planning offer paths to reduce these impacts. Understanding the balance between food production, ecosystem health, and resource use is essential for building a resilient, equitable, and sustainable future.