🌈Earth Systems Science Unit 15 – Biodiversity Loss: Human Impact & Conservation

What's Biodiversity Anyway?

• Biodiversity encompasses the variety of life on Earth at all levels, from genes to ecosystems
• Includes diversity within species (genetic diversity), between species (species diversity), and of ecosystems (ecosystem diversity)
• Genetic diversity ensures populations can adapt to changing environments (disease resistance, climate change)
• Species diversity maintains balance in ecosystems through complex interactions (predator-prey relationships, pollination)
• Ecosystem diversity provides a range of habitats supporting different species (rainforests, coral reefs, grasslands)
• Biodiversity is not evenly distributed across the planet
  • Hotspots are areas with high concentrations of endemic species (species found nowhere else)
• Biodiversity supports essential ecosystem services
  • Provisioning services (food, medicine, raw materials)
  • Regulating services (climate regulation, water purification)
  • Cultural services (recreation, spiritual values)

Human Activities Messing Things Up

• Habitat loss and fragmentation due to land-use changes (deforestation, urbanization, agriculture)
  • Reduces available space for species and disrupts migration patterns
• Overexploitation of natural resources (overfishing, poaching, logging)
  • Depletes populations faster than they can recover
• Pollution (air, water, soil) from industrial activities and waste disposal
  • Toxic substances accumulate in food chains (biomagnification) and harm wildlife
• Climate change driven by greenhouse gas emissions
  • Alters temperature and precipitation patterns, affecting species distributions and phenology (timing of events like migration or flowering)
• Introduction of invasive species through global trade and travel
  • Outcompete native species for resources and disrupt ecosystem balance
• Human population growth and consumption patterns
  • Increased demand for resources puts pressure on biodiversity

Major Threats to Biodiversity

• Habitat loss is the primary driver of biodiversity loss
  • Agricultural expansion accounts for 80% of global deforestation
  • Urbanization leads to loss of natural habitats and increased pollution
• Overexploitation threatens many species
  • Overfishing has depleted fish stocks worldwide (cod, bluefin tuna)
  • Poaching for illegal wildlife trade (elephants, rhinos, pangolins)
• Invasive species can cause extinctions of native species
  • Invasive predators (cats, rats) prey on island species with no natural defenses
  • Invasive plants (kudzu, water hyacinth) outcompete native vegetation
• Climate change is altering ecosystems and species distributions
  • Coral bleaching due to rising ocean temperatures
  • Shifts in species ranges towards the poles or higher elevations
• Pollution affects all levels of biodiversity
  • Pesticides and herbicides harm non-target species (bees, amphibians)
  • Plastic pollution in oceans (entanglement, ingestion)

Ecosystems on the Brink

• Tropical rainforests are biodiversity hotspots under threat
  • Amazon rainforest has lost 17% of its area since 1970
  • Deforestation for agriculture (cattle ranching, palm oil plantations)
• Coral reefs are declining worldwide due to multiple stressors
  • Ocean acidification from increased atmospheric CO2
  • Overfishing disrupts reef ecosystems
  • Coastal development and pollution
• Wetlands are being drained and filled for development
  • 35% of global wetlands have been lost since 1970
  • Wetlands provide critical habitats for migratory birds and fish nurseries
• Grasslands are being converted to cropland and pasture
  • Temperate grasslands (prairies, steppes) are among the most altered ecosystems
  • Overgrazing by livestock degrades soil and vegetation
• Freshwater ecosystems are impacted by dams, pollution, and water extraction
  • Freshwater species are declining faster than terrestrial or marine species
  • Dams block fish migrations and alter river flow regimes

Measuring the Damage

• Current extinction rates are 100 to 1000 times higher than background rates
  • Background extinction rate is ~1 species per million species per year
• The International Union for Conservation of Nature (IUCN) assesses species' extinction risk
  • IUCN Red List categories: Extinct, Critically Endangered, Endangered, Vulnerable
• Biodiversity indices track changes over time
  • Living Planet Index (LPI) measures trends in vertebrate populations
    • LPI has declined by 68% since 1970
  • Red List Index (RLI) tracks changes in species' extinction risk
    • RLI shows an increasing trend towards extinction
• Biodiversity loss is not uniform across taxonomic groups
  • Amphibians are the most threatened vertebrate group (41% of species)
  • Invertebrates are often overlooked but also highly threatened (mollusks, insects)
• Monitoring programs track changes in species populations and distributions
  • Citizen science initiatives (eBird, iNaturalist) engage the public in data collection

Why Should We Care?

• Biodiversity provides essential ecosystem services
  • Pollination by insects is critical for food production (75% of crops)
  • Forests regulate climate and water cycles, store carbon
• Biodiversity is a source of medicines and other useful compounds
  • 25-50% of pharmaceuticals are derived from natural products
  • Potential for new discoveries in unexplored ecosystems (deep sea, rainforests)
• Biodiversity has intrinsic value beyond its utility to humans
  • Ethical arguments for conservation (species have a right to exist)
• Biodiversity loss can have cascading effects on ecosystem functioning
  • Loss of keystone species can lead to ecosystem collapse (sea otters, wolves)
• Biodiversity contributes to human well-being and cultural identity
  • Nature provides recreational, aesthetic, and spiritual benefits
  • Traditional knowledge systems are linked to biodiversity

Conservation Strategies That Work

• Protected areas are a cornerstone of conservation efforts
  • Aichi Target 11: 17% of terrestrial and 10% of marine areas protected by 2020
  • Effective management and connectivity between protected areas is crucial
• Habitat restoration can help recover degraded ecosystems
  • Reforestation and afforestation to restore forest cover
  • Wetland restoration to improve water quality and provide wildlife habitat
• Sustainable resource management practices
  • Ecosystem-based fisheries management to maintain healthy fish populations
  • Sustainable forestry practices (selective logging, certification schemes)
• Captive breeding and reintroduction programs for critically endangered species
  • Success stories: California condor, black-footed ferret
• Addressing the root causes of biodiversity loss
  • Reducing greenhouse gas emissions to mitigate climate change
  • Promoting sustainable consumption and production patterns
• Engaging local communities in conservation efforts
  • Community-based natural resource management
  • Recognizing indigenous peoples' rights and traditional knowledge

What Can We Do About It?

• Support conservation organizations through donations and volunteering
  • Join local conservation groups or wildlife societies
• Make sustainable consumer choices
  • Buy products from certified sustainable sources (FSC-certified wood, MSC-certified seafood)
  • Reduce meat consumption to lower deforestation pressure
• Reduce your carbon footprint to combat climate change
  • Use renewable energy sources, energy-efficient appliances
  • Walk, bike, or use public transportation instead of driving
• Avoid single-use plastics and properly dispose of waste
  • Participate in beach cleanups or other litter removal efforts
• Plant native species in your garden to support local biodiversity
  • Create a pollinator-friendly garden with native flowers
• Educate yourself and others about the importance of biodiversity
  • Share information on social media, engage in discussions
• Advocate for biodiversity-friendly policies
  • Vote for candidates who prioritize environmental issues
  • Support legislation that promotes conservation and sustainable development