3.2: Human Impact On Biodiversity

Question 1

What are some direct threats to biodiversity?

Answer 1

Over exploitation/harvesting:
Rate of harvesting more than natural reproduction -> population decline
Made worse by tech: chainsaws, sonar/trawling nets, etc.
Growing rural poverty -> humans living at subsistence level -> overexploit
-> eg: overfishing in Atlantic Ocean -> population decline)
-> tropical rainforests -> deforestation > reforestation

Poaching:
Illegal hunting, capturing or killing of wild animals due to the demand for valuable animal parts
-> trade/consumption
-> eg: rhino horns, elephant ivory/tusks, exotic skins
-> could lead to extinction

Illegal pet trade:
Exotic animals (snakes, lizards, primates, etc.) wanted as pets
-> often target species that may already be endangered -> especially prized by traders

Question 2

What are some indirect threats to biodiversity?

Answer 2

Habitat loss:
Destruction/fragmentation of habitat via human activity (deforestation, urbanization, etc.)
-> eg: amazon rainforest deforestation for cattle ranching
-> total area reduced
-> remaining habitat fragmented -> roads, power lines, fields, etc.
—> usually surrounded by urbanization
Aquatic habitats: destructive fishing techniques, damage from ships, tourism, pollution
Terrestrial habitats: inland dams, deforestation, desertification, agriculture, pollution
NO HABITAT -> NO SUPPORT SYSTEM

Climate change:
GGG emissions -> habitat disruption, shift in distribution, increased frequencies of extreme weather
-> eg: ice caps melting -> threaten polar bears
CO2 emissions -> burning fossil fuels -> global warming -> abiotic conditions -> species adapt or migrate
-> climate change too extreme -> populations cannot adapt -> decline rapidly/extinct

Pollution:
Introduction of harmful substances or contaminants into the environment
-> eg: plastic pollution in oceans -> marine species
-> local pollution -> oil spills killing seabirds
Environmental pollution -> emissions from factories/transport -> acid deposition of photochemical smog
-> runoff

Invasive species:
Non-native species into ecosystem -> outcompete native organisms for limited resources (no natural predators/pathogens)
-> can happen due to human travel
-> sometimes beneficial (potatoes (Americas -> Europe) and rubber trees (Amazons to SEA))
-> sometimes disaster (cane toads)

Question 3

What is an example of combine impacts?

Answer 3

Most ecosystems -> multiple human impacts simultaneously
-> cumulative effect
-> negative effects amplified -> reduce resilience

Coral reef ecosystem -> overfishing by humans -> lowers resilience to coral bleaching due to climate change -> ecosystem collapse more likely

Question 4

What is the IUCN?

Answer 4

International Union for the Conservation of Nature (IUCN)
-> global authority on the status of the natural world + measures needed to safeguard it

One of duties: assesses the conservation status of animals/plant species around the world
- scientist use data+modeling to estimate category species should be in

Question 5

What is the IUCN redlist? What are the factors used to determine conservation status?

Answer 5

The IUCN red list provides extinction risk assessments

FACTORS:
Population size (smaller population -> greater risk)
Rate of increase/decrease of the population
Degree of specialization
Distribution (geographic range)
Reproductive potential and behavior
Degree of endemicity (is the species only found in a single specific area?)
Degree of habitat fragmentaiton
Quality of habitat
Trophic level (higher trophic level -> greater risk)
Known threats
Probability of extinction

Question 6

What is the IUCN classification system?

Answer 6

Several categories depending on factors like population numbers, threats, risks, etc.
Assigning global conservation status + making public -> allow governments/non-governmental agencies + individual citizen to chose necessary conservation priorities/management strategies

LC = least concern
NT = near threatened
VU = vulnerable
EN = endangered
CR = critically endangered
EW = extinct in the wild
EX = extinct
(DD = data deficient
NE = not evaluated)

Question 7

What is the tragedy of the commons?

Answer 7

Describes the overuse and depletion of a shared resources

Occurs when individuals act in their own self-interest rather than consider the common good
-> degradation of the resource -> unavailable for future use

Question 8

What are the implications for sustainability in regard to the tragedy of the commons?

Answer 8

Overexploitation:
Many natural resources are used faster than can replenish
Means resource depletion -> collapse of certain ecosystems

Impact on biodiversity:
Result in loss of habitats and species
Lead to reduced genetic diversity
= weaken resilience, threaten biodiversity