Overgrazing (College Board AP® Environmental Science) : Study Guide

Impacts of overgrazing

What is overgrazing?

• Overgrazing occurs when too many animals feed on a particular area of land for an extended period

  • This prevents vegetation from naturally regenerating

• It is a major environmental concern in grasslands, savannas, and arid regions where plant regrowth is slow

Impacts of overgrazing

Loss of vegetation

• Overgrazing reduces plant cover, making it harder for grasses and other vegetation to recover

• Leads to biodiversity loss, as native plant species struggle to regenerate

• Disrupts ecosystem balance, affecting herbivores and predators that rely on healthy grasslands

Soil erosion

• With fewer plant roots to hold soil in place, wind and water erosion increase

• Loss of topsoil reduces soil fertility, making it harder for plants to regrow

• Rills and gullies can form, worsening land degradation

Water cycle disruption

• Vegetation loss reduces water infiltration

  • This leads to increased surface runoff

• Can contribute to flooding in some areas and drought conditions in others

• Less water retention in soil leads to lower groundwater recharge

Desertification from overgrazing

How overgrazing contributes to desertification

• Overgrazing is a key driver of desertification, particularly in semi-arid regions

• As plant cover is lost, soil is exposed to harsh sun and wind

  • This accelerates moisture loss

• Without vegetation, the land loses its ability to retain nutrients and support life

Consequences of desertification

• Lower agricultural productivity: Once land becomes desert-like, it can no longer support crops or livestock

• Forced migration: People dependent on grazing lands may be displaced due to land degradation

• Worsening climate change: Desertified land absorbs less carbon, reducing the planet’s ability to mitigate greenhouse gas emissions

Preventing overgrazing and desertification

Rotational grazing

• Moving livestock between different grazing areas allows vegetation to recover naturally

• Prevents soil depletion and maintains a balanced plant ecosystem

Sustainable stocking rates

• Limiting the number of animals grazing in one area prevents excessive plant removal

• Helps maintain healthy pasture conditions

Reforestation and reseeding

• Planting native grasses and trees restores vegetation and stabilizes soil

• Helps increase biodiversity and reduce erosion

Advantages of reducing meat consumption

Environmental benefits

Reduced greenhouse gas emissions

• Lower CO₂, methane, and N₂O emissions: Livestock farming is a major contributor to greenhouse gases

• Less energy-intensive production: Growing plant-based foods generally requires less fossil fuel input than meat production

Water conservation

• Meat production requires large amounts of water for drinking, feed crops, and processing

• Reducing meat consumption helps preserve freshwater resources

Soil health improvement

• Less demand for livestock reduces overgrazing, therefore reducing soil erosion and desertification

• More sustainable agricultural practices can preserve topsoil fertility

Health benefits

Reduced antibiotic and hormone exposure

• Less reliance on antibiotics and growth hormones in livestock means fewer residues in food

• Reducing antibiotic use helps prevent antibiotic resistance in humans

Lower risk of chronic diseases

• Diets with less red and processed meat are associated with lower risks of heart disease, obesity, and certain cancers

Economic and ethical considerations

Lower food production costs

• Producing plant-based foods is generally more efficient and cost-effective than raising livestock

• Helps address global food security by reducing resource-intensive animal farming

Ethical considerations

• Reducing meat consumption supports animal welfare, as fewer animals are raised in intensive farming conditions