Impact of Human Activities on Biodiversity (College Board AP® Environmental Science) : Study Guide

HIPPCO

What is HIPPCO?

• HIPPCO is an acronym describing the main factors leading to biodiversity loss:

  • H: Habitat destruction

  • I: Invasive species

  • P: Population growth

  • P: Pollution

  • C: Climate change

  • O: Overexploitation

• Understanding HIPPCO helps identify strategies to mitigate biodiversity loss

Habitat destruction (H)

• Clearing forests for agriculture, urban development, and logging reduces available habitats

  • Example: Deforestation in the Amazon threatens thousands of plant and animal species

  • Mitigation strategies: Establishing protected areas and reforestation programs

• Other examples include draining of wetlands and destruction of coral reefs

Invasive species (I)

• Non-native species outcompete native species, disrupting ecosystems

  • Example: Kudzu vine in the U.S. smothers native plants, reducing biodiversity

  • Mitigation strategies: Eradication programs and stricter regulations on species introductions

Population growth (P)

• Increased demand for resources leads to habitat loss, pollution, and overexploitation

  • Example: Expanding agriculture to meet food demands leads to soil degradation and deforestation

  • Mitigation strategies: Promoting family planning and sustainable resource use

Pollution (P)

• Air, water, and soil pollution harm species and reduce biodiversity

  • Example: Oil spills and plastic waste in oceans kill marine life

  • Mitigation strategies: Stricter regulations on pollutants and promoting waste management

Climate change (C)

• Changing temperatures and weather patterns alter habitats and migration patterns

  • Example: Coral bleaching due to ocean warming leads to reef ecosystem collapse

  • Mitigation strategies: Reducing greenhouse gas emissions and protecting climate-sensitive areas

Overexploitation (O)

• Overhunting, overfishing, and overharvesting lead to population declines

  • Example: Overfishing of Atlantic cod has led to drastic population reductions

  • Mitigation strategies: Sustainable harvesting practices and catch limits

Causes of habitat fragmentation

What is habitat fragmentation?

• Habitat fragmentation occurs when large, continuous habitats are broken into smaller, isolated patches

  • Often caused by human activities like urban development, agriculture, and infrastructure projects

  • Fragmentation isolates wildlife populations, making it harder for species to find mates, food, and shelter

Main causes of habitat fragmentation

Urban development and roads

• Construction of cities, roads, and highways cuts through habitats, dividing populations

  • Example: Highways in the U.S. have fragmented forests, isolating species like black bears

Agriculture and deforestation

• Clearing land for crops and livestock replaces diverse ecosystems with monocultures

  • Example: Palm oil plantations in Southeast Asia have fragmented tropical rainforests, endangering species like orangutans and tigers

Energy infrastructure

• Power lines, pipelines, and dams create barriers for wildlife movement

  • Example: Hydroelectric dams on rivers prevent fish migration, affecting species like salmon

Mining and resource extraction

• Open-pit mining and logging degrade and fragment habitats

  • Example: Coal mining in Appalachia has removed forests and split habitats

Climate change as an indirect cause

• Changing climate shifts habitats and forces species to migrate, causing indirect fragmentation

Impacts of habitat fragmentation

Why habitat fragmentation is a problem

• Habitat fragmentation reduces the size and quality of habitats, making it harder for species to survive

• Isolated populations are more vulnerable to extinction due to limited gene flow and resources

Main impacts of habitat fragmentation

Reduced genetic diversity

• Smaller, isolated populations have less genetic variation, increasing risk of inbreeding and disease

  • Example: Florida panthers have experienced inbreeding due to habitat fragmentation, causing health and survival issues

Edge effects

• Fragmentation creates more “edges” or boundaries between habitats and human activities

• Edges are often less suitable for many species, increasing predation and competition

  • Example: Bird nests near forest edges are more prone to predation

Awaiting image: Habitat fragmentation
Image caption: Habitat fragmentation can potentially lead to a loss of "interior" or "core" species but may not affect "edge" species to the same extent

Barriers to migration and dispersal

• Roads, fences, and urban areas prevent species from moving freely between habitat patches

  • Example: Highways in California have reduced mountain lion movement, causing genetic isolation

Altered species interactions

• Fragmentation can disrupt food webs and predator-prey relationships

  • Example: Fragmented forests may allow generalist species like raccoons to thrive, increasing predation on native birds

Increased vulnerability to climate change

• Isolated habitats limit the ability of species to migrate in response to climate shifts

  • Example: Amphibian populations in fragmented wetlands may struggle to move to cooler areas as temperatures rise

Global climate change & habitat loss

How does climate change cause habitat loss?

• Global climate change alters temperature, precipitation patterns, and sea levels, directly impacting habitats

  • Some species cannot migrate or adapt quickly enough to survive these rapid changes

Main ways climate change causes habitat loss

Temperature shifts

• Rising temperatures push species out of their optimal temperature range, reducing suitable habitats

  • Example: Arctic sea ice loss is shrinking habitats for polar bears and seals

Changing precipitation patterns

• More frequent droughts or intense rainfall can degrade habitats, making them less suitable

  • Example: Droughts in California affect migratory birds because they dry up wetlands, which are critical stopover points for these birds to rest, feed, and hydrate during their long migrations

Sea level rise

• Rising sea levels flood coastal habitats like mangroves, salt marshes, and estuaries

  • Example: Florida Everglades are threatened by saltwater intrusion due to rising sea levels

Ocean warming and acidification

• Warmer oceans cause coral bleaching, leading to loss of coral reef habitats

• Ocean acidification weakens coral skeletons, reducing habitat complexity

  • Example: Great Barrier Reef has experienced mass bleaching events due to warming seas

Increased frequency of wildfires

• Higher temperatures and droughts increase the likelihood of wildfires, destroying habitats