Environmental Science Exam 2

What are the different trophic levels in a food chain/web?

Producers → Primary consumers → Secondary consumers → Tertiary consumers → Decomposers.

How do food and contaminants move in a food chain?

They move upward and become more concentrated at higher levels (biomagnification).

How much biomass is incorporated into the next trophic level?

About 10% (the rest is lost as heat or waste).

What are the main differences between terrestrial, aquatic, and detrital food webs?

Terrestrial: Based on plants.

Aquatic: Based on phytoplankton/algae.

Detrital: Based on decomposing organic matter.

Why are terrestrial trophic levels less efficient than aquatic systems?

Plants are harder to digest (cellulose).

How many trophic levels do most ecosystems support?

Typically 3-5 levels.

What are ecosystem disturbances?

Events that disrupt ecosystem structure or function (e.g., fire, floods, storms, human activity).

What is ecological succession?

Gradual change in species composition over time.

What are the types of succession?

Primary: Starts on bare rock (no soil).

Secondary: Occurs after disturbance (soil present).

What role does fire play in succession?

ire resets succession and maintains certain ecosystems (e.g., grasslands, pine forests).

What are biomes?

Large ecological regions defined by climate, vegetation, and organisms (e.g., desert, tundra, rainforest).

What factors control biome distribution?

Climate, temperature, precipitation, elevation, and distance from the equator.

Which biomes are most productive and why?

Tropical rain forests and estuaries — warm, wet, high nutrient availability.

What are climatic trends with elevation and latitude?

Higher elevation or farther from the equator = colder and drier climates.

What are small regions where climate differs from the surrounding area called?

Microclimates.

Define a tipping point.

A threshold where small changes cause large, irreversible ecosystem shifts.

What is the Millennium Ecosystem Assessment?

A global study (2005) that found 60% of ecosystem services are being degraded by humans.

How is biome or aquatic productivity measured?

Net Primary Productivity (NPP) - rate of biomass production by plants.

What is biological wealth?

The combined value of all living things — biodiversity, ecosystems, and ecological services.

What is biodiversity?

The variety of life in all forms, levels, and combinations — includes species, genetic, and ecosystem diversity.

What's the difference between instrumental and intrinsic value?

Instrumental: Value for human use (e.g., medicine, food).

Intrinsic: Value simply because it exists.

What are the consequences of biodiversity loss?

Loss of ecosystem stability, fewer resources, and increased vulnerability to change.

Which areas harbor the most biodiversity and why?

Tropical rainforests and coral reefs — stable climate, high productivity, and habitat variety.

What are examples of habitat destruction?

Deforestation, urbanization, agriculture expansion, mining.

What does the acronym "HIPPO" stand for?

Habitat loss, Invasive species, Pollution, Population (human), Overexploitation.

What types of pollutants were discussed in class?

Chemical pollutants (pesticides, heavy metals), air pollutants, nutrient pollution (fertilizer runoff).

What is fragmentation?

Breaking large habitats into smaller, isolated patches (e.g., roads cutting through forests).

How does fragmentation differ from simplification?

Fragmentation: Splits habitats.

Simplification: Removes key species or reduces habitat complexity (e.g., clear-cutting).

Why do the mountains of Haiti look different from those in the Dominican Republic?

Haiti has extreme deforestation for fuel and farming; Dominican Republic has more forest protection.

What are invasive species?

Non-native species that spread rapidly and harm ecosystems.

Give an example of an invasive species.

Zebra mussel in North America — clogs pipes and outcompetes native species.

Why do invasive species spread so successfully?

Few natural predators and high reproductive rates.

What issues do invasive species cause?

Displace native species, alter food webs, reduce biodiversity, and cause economic damage.

What are the categories of ecosystem use?

Provisioning - things we take (food, water, timber).

Regulating - things that control nature (climate, floods, pollination).

Cultural - things we enjoy (recreation, spirituality, beauty).

Supporting - things that support life (soil, nutrients, habitat

People Really Care, Seriously

Give examples of ecosystem use.

Consumptive: Gathering firewood.

Productive: Commercial logging.

Nonconsumptive: Ecotourism.

What is the difference between conservation and preservation?

Conservation: Sustainable use of resources.

Preservation: Protecting nature from use or alteration.Example: National forests (conservation) vs. national parks (preservation).

What are the types of ecosystem use?

Direct use, indirect use, option use, and existence value.

Name the different types of land tenure and their restrictions.

Private: Owned by individuals; most control.

Common: Shared by community.

State: Managed by government.

Open access: No restrictions → often overused.

What is Maximum Sustainable Yield (MSY)?

The largest harvest that can be taken without depleting the resource.

What population level allows MSY?

Around half the carrying capacity (K/2).

How does MSY relate to the precautionary principle?

When data are uncertain, manage resources conservatively to avoid collapse.

What is the most productive type of ecosystem?

Estuaries, wetlands, and tropical rainforests.

What did the Global Forest Resource Assessment conclude?

Global deforestation is slowing but continues heavily in tropical regions.

Name and describe forms of forest management.

Clear-cutting: All trees removed (least sustainable).

Selective cutting: Only mature trees removed.

Shelterwood cutting: Gradual removal in stages

What are sustainable forest strategies?

Replanting, reduced-impact logging, certification programs, and mixed-species reforestation.

What is an ecolabel? Give an example.

A certification showing sustainable sourcing. Example: FSC (Forest Stewardship Council) for wood products.

What are the consequences of deforestation?

Soil erosion, loss of biodiversity, carbon release, and disrupted water cycles.

Which areas are most affected by deforestation?

Amazon Basin, Central Africa, and Southeast Asia.

What ecosystems are under the most pressure and why?

Forests, coral reefs, wetlands — due to overexploitation, pollution, and land conversion.

What are some problems with aquaculture?

Pollution, disease spread, escape of non-native species, and habitat destruction (e.g., shrimp farming in mangroves).

How can aquaculture be made more sustainable?

Integrated systems, using native species, recycling water, and sustainable feed.

What are main problems with marine systems?

Overfishing, coral bleaching, plastic pollution, and acidification.

What lands are protected by law in the U.S.?

National Parks, Wildlife Refuges, National Forests, Wilderness Areas, and Marine Protected Areas (MPAs).

What is the study of demography?

The study of human populations — size, growth, density, distribution, and structure.

What is the estimated carrying capacity for humans?

Roughly 8-10 billion (depends on consumption and technology).

What revolutions promoted population growth?

Agricultural Revolution: More food, stable settlements.

Industrial Revolution: Improved medicine and sanitation.

Green Revolution: Increased crop yields.

What are the environmental and social consequences of rapid population growth in developing nations?

Resource depletion, pollution, unemployment, and poor living conditions.

What are consequences of population growth in developed nations?

High resource consumption and large ecological footprints.

What environmental issues most impact impoverished groups?

Lack of clean water, deforestation, and pollution.

Rural: Soil erosion, poor agriculture.

Urban: Air and water pollution.

What is the relationship between poverty and fertility rates?

Higher poverty = higher fertility, due to lack of education and family planning.

Define Total Fertility Rate (TFR).

Average number of children a woman has in her lifetime.

What is replacement-level fertility?

About 2.1 children per woman — maintains population size.

Which countries have the highest TFR?

Least developed countries in Sub-Saharan Africa.

What is the IPAT formula?

Impact = Population × Affluence × Technology.

How does affluence affect the environment?

Increases consumption and waste.

How does poverty affect the environment?

Leads to resource overuse (e.g., deforestation for survival).

What are population profiles?

Graphs showing age and sex distribution in a population.

What does population momentum tell us?

Even if fertility drops, populations may keep growing due to many young people.

How do population age structures differ between developed and developing countries?

Developed: More older adults, stable/declining growth.

Developing: Many young people, rapid growth.

What are the phases of demographic transition?

1️⃣ Pre-industrial: High birth/death rates.2️⃣ Transitional: Death rates fall, birth rates stay high → rapid growth.3️⃣ Industrial: Birth rates drop.4️⃣ Post-industrial: Low birth/death rates, stable or shrinking population.

What phase is the U.S. in?

Post-industrial.

What phase are most developing countries in?

Transitional or early industrial.

What factors lead to smaller families?

Education, urbanization, family planning, and women's empowerment.

What factors lead to large families?

High infant mortality, cultural traditions, and agricultural labor needs.

What is the poverty trap?

A cycle where poverty leads to environmental degradation → fewer resources → continued poverty.

What is the demographic dividend?

Economic boost from having many working-age adults and fewer dependents.

What is a dependency ratio?

The ratio of dependents (young + old) to the working-age population.