EVS Final Exam

Chapter 4, 6, 8, 7, 11, 12

Species Diversity

species richness + species evenness

Species Richness

The number of different species in community

Example:

• Forest with 20 different species = high richness

Species Evenness

How evenly individuals are distributed among species

Example:

• 4 species with 25 individuals each = high evenness

• 1 species with 90 individuals, others with 2–3 = low evenness

Biome

large geographic area recognized
by their distinct structures Ex. biotic & abiotic factors, rainfall & and temps

*can be terrestrial or aquatic

Latitude

Def. distance from the equator
* Ecosystems near the equator have much more diversity!
○ More physical space in the tropics
○ More sunlight
○ Relatively stable climate
○ We don’t totally know why!

Equilibrium Model of Island Biogeography

The number of species
on an island is the result of a balance
between the rate at which new species
arrive and species on the island become
locally extinct

* Shaped by:
○ Island size = Larger target - more immigrants & less extinction because can maintain larger pop.
○ Distance to shore = more immigrants from close proximity - leads to less extinction because sustained by rate of immigration

Keystone Species 

Exert significant
effect on biodiversity despite low
abundance. Usually a top-level predator Ex. Wolve 

Ecosystem Engineer

Manipulate the
physical environment and influence
ecosystem structure. Ex. Beaver

Foundation Species

Create the physical
framework for the community using
their own bodies Ex. Trees = provide shelter and home for birds

Succession 

Gradual change in a
community over time Ex. Wild flowers growing on side of mountain after volcanic erruption

Primary Succession

succession on a
bare geological surface, such as a lava
flow
○ Slow, takes decades to get fresh soil

Pioneer Community

First community to develop during succession. Generally made of species tolerant to exposure of full sun and harsh conditions

Secondary Succession

succession following the disturbance of an established community that doesn’t
destroy all living creatures or soil

Climax Community

The community at
the end of a successional sequence that
persists until a disturbance disrupts it
sufficiently to restart succession

Ecosystem Services 

1. Supporting: Foundational services like
energy flows and nutrient cycles
2. Provisioning: Products obtained from
the ecosystem
3. Regulatory: Processes derived from
ecosystems
4. Cultural: Non-material benefits
○ Recreation, tourism, aesthetic inspiration

Isolated Patches 

Definition:
Areas of habitat that are separated from other similar habitats by human development or natural barriers, limiting movement of organisms between them.

Why It Matters:

• Reduces gene flow

• Lowers biodiversity

• Increases risk of local extinction

Ex.

• Small forests separated by highways or cities

Habitat Fragmentation

Definition:
The process where a large, continuous habitat is broken into smaller, isolated patches.

Causes:

• Roads

• Cities

• Farming

• Dams

Effects:

• Creates isolated patches

• Reduces gene flow

• Lowers biodiversity

• Increases edge effects

Edge Effects

Changes that happen at the border of a habitat, often harming species that need the interior environment.

Caused By:

• Habitat fragmentation

• Creation of isolated patches

Examples of Edge Effects:

• More sunlight & wind

• Higher temperatures

• More predators & invasive species

• Lower survival of interior species

Why It Matters:

• Harms specialist species

• Reduces biodiversity

• Makes ecosystems less stable

Protected Areas

Geographically defined area that is
designated or regulated as damaged to
achieve a particular conservation
objective Ex. Sichuan Giant Panda Sanctuary

*Strict nature reserve= No tourism specifically for scientific research only

*Size (bigger is better, but not always possible) & connection/ continuous zone (linkage of land substantiable habitat to increase movement of wildlife) is key

Non-Gov & Ngo role on conservation

Not all protected areas are run by the
government!
* NGOs have more flexibility compared to the government

Ex. World Wildlife Fund

Gene Def.

Stretch of DNA that directs the
growth, development, and functioning of
an organism

Genetic Diversity

Different gene
combinations found within a single
population or species Ex.

Natural Selection

Those with more
favorable genetic traits survive better
than others

Domestication

The deliberate change
of a wild animal or plant species to
better meet the needs of humans Ex. Dogs & bananas

*problem = threat to biodiversity Ex. bananas only having one type now because before there were more types but are vulnerable to disease - now may have to create a new variation to sustain our demand

J-Shaped (exponential) Growth 

As long as growth
remains fixed, the population size will
increase faster and faster over time until crash (die and run out of resources)

S-Shaped (logistic) Growth

Limited essential resources can cause the rate of growth to slow down and eventually level off at
carrying capacity

Carrying Capacity (K)

the number of individuals in a population that an environment can support over the long run

Life History

Characteristics of a species
and the rate at which young survive

K-Selected Species

○ Regulated by density dependent factors
○ Few offspring & parental intensive care

Ex. Whales & Elephants - pop. is effected and controlled by limited food and space, competition, and use of natural resources

R-Selected Species

○ Rapid growth when the environment is
favorable
○ Small and subject to catastrophic
mortality from density independent
factors
○ Lots of offspring, little parental
investment
○ Live fast, die young!

Ex. Insect - pop. is effected and controlled by pesticides, temp changes, and natural disasters 

Threats to Biodiversity #1 Habitat Destruction

We live in the Anthropocene def. a time period where humans shape the planet more than natural processes
● Habitat alteration and destruction are
the most serious threats to biodiversity

Ex. Loss of sea ice habitat for polar bears, seals, and penguins

Threats to Biodiversity #2 Invasive Species

When introduced to a new environment, pose a serious threat
to native populations
● Not hindered by their own natural
predators, parasites, and pathogens
● Happens when humans bring species to new places

Ex. Zebra mussels in the Great Lakes – outcompete native mussels and clog water infrastructure.

Threats to Biodiversity #3 Plant and Wildlife Trafficking

Species killed or removed from the
environment for human use
○ Demand for exotic pets
○ Flashy hunting trophies

Ex. Rhinos, elephants, exotic birds

Threats to Biodiversity #4 Pest and Predator control  

Predators seen as threats to livestock
are killed without considering effect on
ecosystems
● Pest control introduces toxins that
harm species

Ex. Weeds- herbicides used in agriculture

Solutions to biodiversity threats- The Endangered Species Act

1- The Endangered Species Act protects
both domestic and foreign endangered
species

Solutions to biodiversity threats- The Lacey Act 

2- The Lacey Act forbids the trading of
illegally harvested plants and animals

Solutions to biodiversity threats (Suggestions)

-  Prevent spread of invasive species
-  Ban toxins responsible for endangering species

Solutions to biodiversity threats- Economic Incentives 

• Encourage ecotourism

• Regulated hunting

• Drugs produced from different plants

Distribution of Water on Earth

1. Oceans = 97% of all water
2. Freshwater mostly in polar ice caps
3. Next largest = groundwater
4. Very little freshwater in lakes, rivers, wetlands

Frozen Water

1. Glaciers

• Losing mass since 1970s

• 95% near the poles

• Melting → sea level rise & ocean current disruption

2. Sea Ice

• Mostly seasonal (~15% of oceans)

• Melting does not add water

• High albedo → reflects sunlight, cools Earth

• Less sea ice → warmer oceans → affects global climate

Hydrologic Cycle

def. The movement of Earth’s water between the oceans, atmosphere,
and terrestrial and freshwater environment

Connection between oceanic and terrestrial sub cycles (Hydrologic Cycle)

1. Ocean → land: precipitation falls on land
2. Land → ocean: surface runoff flows back to the ocean

Water Use 

 We use >50% of accessible runoff water globally
 Main uses:

• Irrigation

• Diluting sewage/waste

• Rivers for shipping

• Recreation

Lakes & Ponds (lentic)

• Standing water

• Classified by distance from shore & sunlight penetration

Rivers & Streams (lotic)

• Flowing water

• Classified by flow differences

Wetlands & estuaries  

• Wetlands = water-saturated land

• Estuaries = freshwater + saltwater meet

Dams- Pros vs. Cons

Pros:

• Emission-free power (hydropower)

• Regulate water supply (store water during droughts)

Cons:

• Rivers dry up downstream

• Reduce nutrient flow below dam

• Change water temperature

• Block fish migration → affects aquatic biodiversity

Dam removal- Pros vs. Cons

Term: Dam Removal

Pros:

• Restore natural ecosystems

• Reestablish fish migration and river flow

Cons:

• Lose clean hydropower

• Ecosystem recovery not guaranteed

• Release trapped pollutants downstream

Floods & Wetlands

• Floods = rivers/streams overflowing banks

• Wetlands need floods to thrive

• Critical in dry water-scarce areas for biodiversity

• Human changes to flooding harm wetlands

Erosion- Def. + problems

Def. =The removal and movement of soil or rock by wind, water, ice, or gravity.

Problems= Humans speed up erosion by: 

• Removing water / lowering water tables

• Deforestation → no roots to hold soil

Groundwater Depletion

• Pumped faster than recharge

• Some areas use fossil water (non-renewable aquifers)

• Harms groundwater-dependent ecosystems

  • Low flow, warmer streams → hurts salmon & trout

Ex. Ogallala Aquifer

Subsidence 

def. The sinking of land when groundwater-filled spaces collapse.

• Caused by overpumping groundwater

• Permanent loss of aquifer storage capacity

• Leads to land sinking, infrastructure damage, and reduced water supply

Irrigation

• Waterlogging

  • Soil becomes too saturated → roots can’t get oxygen

• Soil Salinization

  • Water evaporates and leaves salt behind

  • Salt buildup harms crops and reduces soil fertility

Why water rights are hard to define

• Hard to measure needs - daily water needs vary by environment, age, weight etc. 

• Debate: water = human right vs. commodity

  • UN recognizes the right to water (2010), but many countries abstained

• Legal/political problems:

  • Who pays to move water across borders?

  • Should countries share water with growing neighbors?

  • How much water is each person guaranteed?

Water reclamation 

Definition:

• Treating wastewater so it can be reused or recycled.

Treatment Levels & Uses:

1. Primary:

   • No reuse

2. Secondary:

   • Irrigate orchards/vineyards

   • Wetland restoration

   • Industrial uses

3. Tertiary:

   • Irrigate food crops

   • Landscaping

   • Recreational water (ponds, lakes)

   • Add to surface reservoirs for drinking supply

Regulations keeping freshwater clean

1. Safe Drinking Water Act (SDWA)

• Sets maximum contaminant levels for drinking water

• Protects water at the tap

2. Clean Water Act (CWA)

• Regulates pollution discharge into water bodies

• Protects rivers, lakes, wetlands from contamination

Thermohaline Circulation Def. & movements

Def. Global movement of ocean water driven by temperature (thermo) and salinity (haline).

Key Points:

• Warm water moves north → cools → becomes dense → sinks

• Controls global climate patterns

• Keeps Europe warm compared to similar latitudes (ex: Bordeaux vs. Portland, Maine)

• AMOC = part of thermohaline circulation

Thermohaline collapse (if it failed) 

Major Consequences:

1. Dramatic cooling in Europe & North America

2. More flooding & storms in the Pacific

3. Collapse of plankton (base of food web)

4. Climate shifts in tropics, Alaska, Antarctica

5. Stronger & more frequent El Niño events

6. Low oxygen below ocean surface → mass extinctions

El Nino

🌞Where:

• Equatorial Pacific Ocean, west of South America

What It Is:

• Warmer than normal sea surface temperatures

• Low atmospheric pressure

Climate Effects:

• Warm & dry winters in some regions

• Alters global rainfall patterns

La Nina

❄ What It Is:

• Colder than normal sea surface temperatures

• High atmospheric pressure

Climate Effects:

• Very wet winters in Southeast Asia

• Warmer winters in the Southern Hemisphere

ENSO (El Nino southern oscillation)

Def.  The natural climate cycle between El Niño & La Niña

*It is a normal swinging pattern, not always caused by climate change

Upwelling

Def. When cold, nutrient-rich water rises to the ocean surface

Importance:

• Supports plankton & fisheries

• Cold surface spots can signal circulation changes

Marine Primary Production

Def. Energy production by phytoplankton through photosynthesis

Controlled By:

• Ocean temperature

• Ocean salinity

• Ocean nutrients

Euphotic vs Disphotic 

• Euphotic Zone: Enough light for photosynthesis

• Disphotic Zone: Some light, no photosynthesis

Upwelling + Fisheries

Why It Matters:

• Feeds phytoplankton

• Supports productive fisheries

El Nino + Fisheries

What Happens:

• Warm surface water moves in

• Disrupts winds & upwelling

• Nutrients can’t reach euphotic zone

Results:

• Commercial fish populations drop

• Seabird & marine mammal deaths

Why human whaled + Consequences

Uses:

• Meat

• Blubber → oil, makeup, soap, margarine, industrial oil

Why It Became a Crisis:

• Bigger boats → easier killing

• Mostly in international waters → no laws

• Led to population collapse

Regulation- International Whaling Commission (IWC)

• Created to set hunting quotas

• 1982: Commercial whaling banned

• Many whale populations are now recovering

Why whaling still continues

• Cultural traditions

  • Indonesia, Alaska, Canada

• Commercial / “scientific” whaling

  • Japan left IWC (2019)

  • Iceland still permits whaling

Tragedy of the commons- Fisheries

Why Overfishing Happens:

• Non-excludable = anyone can fish

• Rivalrous = less fish for others

• Individuals act for personal gain

Solution 1- Private Property

• Old rule: short season → race to fish

• New rule: guaranteed share of catch or area

• Encourages long-term sustainability

Solution 2- Pigouvian Tax

• Fishing licenses limit who can fish (but easily given out)

• Economic control to reduce overuse

• Small-scale but somewhat effective

Marine Reserves- Types + Ex. 

Definition:

• Ocean areas with restricted or banned fishing

Types:

• Permanent no-take

• Seasonal closure

Benefit:

• Fish populations recover & spill over

Ex. Cabo Pulmo 

• Overfished in 1990s

• Became no-take reserve

• Fish biomass increased ~5× in 10 years

• Coral reef recovery

• Boosted eco-tourism & local economy 

Aquaculture

Definition:

• Breeding & raising fish, shellfish, algae for food

Why It’s Used:

• Rising food demand

• Rapid industry growth

Land-based aquaculture

def. Fish raised in indoor tanks with filters

Ex.

• Salmon in China & Middle East deserts

• Tuna in Japan

*Downside: expensive, energy & water intensive

Problems with aquaculture

• Escaped fish become invasive

• Water pollution from waste & chemicals

• Disease & parasite transfer to wild fish

• Carnivorous fish still require wild-caught feeder fish

IMTA- Integrated multi-trophic aquaculture

Def. Raising multiple species from different trophic levels together

Pros=

• Waste from one species feeds another

• Reduces pollution & disease

• Less fish meal needed

• Fewer pesticides

Aquatic-Terrestrial Linkage

Definition:

• Connections between water ecosystems and land ecosystems where energy, nutrients, organisms, and carbon move between them

Key Idea:

• What happens in streams, rivers, and lakes directly affects nearby land ecosystems

Riparian food web 

Definition:

• Food webs that exist along stream and river edges (riparian zones)

Key Connections:

• Aquatic insects emerge from water → become food for land predators (birds, spiders)

• Nutrients move from water → into terrestrial ecosystems

Why Important:

• Streams support biodiversity on land

Human impact on riparian ecosystems

1 Pollution (pesticides, chemicals) → kills aquatic insects

2 Fertilizer runoff → changes aquatic community

3 Dams & channels → destroy insect larval habitat

4 Habitat destruction → removes riparian vegetation

Result:

• Disrupts food supply for terrestrial predators

How to protect riparian ecosystems 

Solutions:

• Protect stream health

• Increase riparian buffer zones

• Restore natural water flow + vegetation

Why It Matters:

• Freshwater management = protects land biodiversity too

Land + Atmosphere carbon exchange

Old View:

• Land and water tracked separately

New Understanding:

• Carbon moves laterally through watersheds

• Carbon travels by:

  • Surface runoff

  • Groundwater flow

• Carbon can be:

  • Released into the atmosphere

  • Buried in aquatic sediments

Big Idea:

• Carbon cycling is land + water + atmosphere together

Measuring carbon exchange-

Top down vs Bottom up 

Top-Down Method (Atmosphere Based):

• Measures total carbon exchange from above

• ✅ Sees the big picture

• ❌ Doesn’t explain exact ecosystem processes

Bottom-Up Method (Land Based):

• Adds together carbon from forests, lakes, farms, etc.

• ✅ Explains how ecosystems work

• ❌ Accuracy depends on good ecosystem data

Net Watershed Exchange (NWE)

Definition:

• Measures total carbon balance of an entire watershed

Includes:

• Carbon stored in ecosystems

• Carbon exported by streams

Why Better:

• Looks at whole carbon system, not just water transfer

Virtual Water

Def. The hidden water used to produce goods, especially food and crops

• Example: Water used to grow cotton or cocoa

Why do water-scarce countries export virtual water?

Economic Reasons:

• Comparative advantage (they make more money exporting)

• National economies may depend on these exports

• Example: Cotton industry

Cultural & Social Reasons:

• Farming water-intensive crops is tied to:

  • Tradition

  • Social status

  • Community identity

• Example: Volta Basin (Ghana): cocoa farming & livestock

Big Idea:

• Money + culture often outweigh water shortages

Terrestrial Primary Production

3 Most Important Factors:

• Climate – controls rate of photosynthesis

• Biodiversity – different species fill different roles → increases stability & productivity

• Nutrients (soil) – soil supplies nutrients needed for plant growth

Nitrogen importance

Nitrogen:

• Essential for amino acids & proteins

• Supports plant growth & food chains

• Often the limiting nutrient in terrestrial ecosystems

Nitrogen Cycle

Definition:
The movement of nitrogen through and between ecosystems

Main Steps to Know:

• Nitrogen fixation

• Decomposition & ammonification

• Nitrification

• Assimilation

• Denitrification

• Weathering

Soil importance

Soil Is More Than Dirt

Soil Is:

• A living system

• Made of:

  • Sand

  • Silt

  • Clay

Soil Development:

• Takes hundreds to thousands of years

How nutrients enters and leaves soil

Nutrients Enter Through:

• Nitrogen fixation

• Weathering

• Deposition

• Plant litter

• Sedimentation

Nutrients Leave Through:

• Erosion

• Leaching

• Gaseous emissions

Erosion

Definition:
Movement of soil from one place to another

Causes:

• Farming

• Construction

• Deforestation

• Overgrazing

Effects:

• Loss of nutrients

• Reduced soil fertility

• Lower crop yields

Ways human get food

Foraging:

• Hunting, fishing, gathering

Agriculture:

• Extensive – small land, more labor

• Intensive – large land, less labor, high inputs

Uses:

• Plows

• Draft animals

• Irrigation

• Fertilizers

• Pesticides

Green Revolution

Time Period:

• Mid-20th century

Goal:

• Increase food production & reduce hunger

Key Figure:

• Norman Borlaug

Results:

• ✅ Increased yields

• ✅ Reduced hunger

• ❌ Environmental damage

• ❌ Increased inequality

• ❌ Big corporations replaced local farms

Agroecology

Def.
Farming using ecological knowledge to increase sustainability & biodiversity

Includes:

• Crop rotation

• Intercropping

• Low-till & no-till

• Cover crops

• Green manure

• Organic farming

Key Idea:

• Farms function like ecosystems

Agroforestry

Def.
Combining trees + crops in farming

Benefits:

• Reduces erosion

• Helps fight climate change

• Limits deforestation

Challenge:

• Must match natural species correctly

Indigenous knowledge in farming

Why It Matters:

• Proven sustainable techniques

• Improves:

  • Soil management

  • Crop rotation

  • Intercropping

Example:

• Three Sisters = corn, beans, squash

Natural Farming

Definition:

• Rejects modern chemical-based farming

Pros:

• Very eco-friendly

Cons:

• Productivity depends on high skill & experience

Example:

• Ducklings in East Asia for weed & pest control

Ranching & Overgrazing

Ranching:

• Raising livestock

Problems:

• Requires large land & energy

• Causes overgrazing

Overgrazing Effects:

• Up to 100 tons of soil lost per hectare per year

• Leads to desertification

Example:

• Sahel region

Forest management practice #1

Clear-cutting

• Most economical

• Removes all trees

• High erosion