Human Impacts on Ecosystems & Conservation Biology (Ch. 43 Study Guide)

Human Impacts & Conservation Biology

Levels of Biodiversity

Biodiversity refers to the variety of life at different levels of biological organization. Maintaining biodiversity is crucial for ecosystem stability, resilience, and the provision of ecosystem services.

• Genetic Diversity: The variety of genetic information within and among individuals of a population, species, or community.

  • Example: Different breeds of dogs or varieties of crops like rice.

  • Importance: Provides the raw material for adaptation and evolution. Loss of genetic diversity can make populations more susceptible to diseases and environmental changes.

  • Risk of Loss: Populations with low genetic diversity may not survive new diseases or climate changes.

• Species Diversity: The variety of species within a region or ecosystem.

  • Example: The Amazon rainforest contains thousands of plant and animal species.

  • Importance: Each species plays a unique role in its ecosystem (niche). Loss of species can disrupt ecosystem function.

  • Risk of Loss: Extinction of a species can lead to cascading effects on other species and ecosystem services.

• Ecosystem Diversity: The variety of ecosystems in a region.

  • Example: Forests, wetlands, grasslands, and coral reefs in a single country.

  • Importance: Diverse ecosystems support a wider range of species and ecological processes.

  • Risk of Loss: Loss of ecosystem types reduces the planet’s ability to support life and provide resources.

Ecosystem Services

Ecosystem services are the benefits that humans obtain from ecosystems. These services are essential for human survival and well-being.

• Provisioning Services: Products obtained from ecosystems (e.g., food, water, timber, fiber).

• Regulating Services: Benefits from regulation of ecosystem processes (e.g., climate regulation, disease control, water purification).

• Supporting Services: Services necessary for the production of all other ecosystem services (e.g., soil formation, nutrient cycling, pollination).

• Cultural Services: Non-material benefits (e.g., recreation, spiritual value, aesthetic enjoyment).

Examples of Ecosystem Services:

• Pollination of crops by insects

• Purification of water by wetlands

• Flood regulation by forests and wetlands

• Climate regulation by forests (carbon sequestration)

• Soil fertility maintained by decomposers

• Provision of medicines from plants

Discussion: The statement “Without ecosystem services there are no human beings” is not exaggerated, as humans depend on these services for food, clean water, air, and climate stability.

Primary Human Threats to Biodiversity and Ecosystem Services

Human activities have accelerated the loss of biodiversity and the degradation of ecosystem services.

Threat	Example
Habitat Loss	Deforestation for agriculture or urban development
Introduced Species	Zebra mussels in North American lakes
Overharvesting	Overfishing of cod populations
Global Change (including climate change, pollution)	Coral bleaching due to rising sea temperatures

Greatest Threat: Habitat loss is currently considered the greatest threat to biodiversity.

Conservation at Species, Landscape, and Regional Levels

Conservation efforts often require action beyond the species level, considering entire landscapes and regions.

• Example: Protecting the Florida panther requires preserving large tracts of habitat and maintaining corridors for movement.

• Reason: Species depend on interactions with other species and their environment; saving one species often means protecting its ecosystem.

• Conflicting Demands: Conservationists may need to choose between preserving farmland for food production and restoring natural habitats for endangered species.

Bio-magnification

Bio-magnification is the process by which certain toxic substances become more concentrated at each trophic level in a food chain.

• Definition: The increase in concentration of a substance, such as a pesticide, as it moves up the food chain.

• Food Chain Dynamics: Organisms at higher trophic levels consume many individuals from lower levels, accumulating higher concentrations of toxins.

• Example: DDT accumulates in fish-eating birds, causing eggshell thinning and population declines.

Atmospheric CO2, Global Temperatures, and Impacts

Rising atmospheric CO2 levels are linked to global warming, which affects species and ecosystems worldwide.

• Greenhouse Gases: Gases like CO2 trap heat in the atmosphere, raising Earth's temperature.

• Increase in CO2: Human activities such as burning fossil fuels and deforestation have increased atmospheric CO2 over the past century.

• Long-term Effects: CO2 remains in the atmosphere for decades, so emissions today will affect climate for at least 50 years.

• Impacts: Species may shift their ranges, face extinction, or experience altered life cycles; ecosystems may lose function or collapse.

$\text{CO}_2 + \text{H}_2O \rightarrow \text{H}_2\text{CO}_3$ (carbonic acid formation in oceans, leading to acidification)

Mitigating Climate Change and Limiting Extinctions

Human actions can reduce the impacts of climate change and help prevent biotic extinctions.

• Examples:

  • Reforestation projects to absorb CO2

  • Establishing protected areas to conserve habitats

  • Restoring wetlands to improve water quality and provide wildlife habitat

  • Reducing fossil fuel use by transitioning to renewable energy

  • Promoting sustainable agriculture and fisheries

  • Legislation to limit emissions (e.g., Paris Agreement)

• Personal Actions: Individuals can reduce their carbon footprint, support conservation organizations, and advocate for policy changes.

Most Effective Personal Action: Answers will vary, but may include reducing energy use, supporting renewable energy, or participating in habitat restoration projects.

Additional info: Conservation biology is an interdisciplinary field that integrates ecology, genetics, policy, and social sciences to address the loss of biodiversity and promote sustainable human-environment interactions.