Human Impact Flashcards
4 reasons why are species at risk?
1) human activities after ecosystems
2) mass destruction of habitats for mining etc
3) biodiversity crisis- loss of biotic and abiotic factors
4) means reproduce less successfully
What is meant by extinction?
natural process of loss of a species but humans are now the main cause
vast majority of species extinct due to change in climate, geological and abiotic factors
What is meant by endangered species?
threatened by extinction, graded according to vulnerability (numbers, rate of decline, distribution)
What are the three main reasons species are threatened?
1) Natural selection
2) Non- contiguous populations
3) Loss of habitat
Describe how natural selection is threatening species
- individuals less suited to conditions produce less successfully
- humans changing conditions quicker than species can adapt
Describe how non-contiguous populations are threatening species
- total no. of individuals in species may suggest numbers are sufficient to continue
- if isolated cannot interbreed
Describe how loss of habitat is threatening species (7)
- DEFORESTATION
- DRAINAGE OF WETLANDS
- HEDGEROW LOSS
increase field size for machinery means loss of nests - SOW CROPS IN AUTUMN NOT SPRING
unsuitable height for nests - OVERHUNTING
profit/ food/ trophy/ medical - COMPETITION OF INTRODUCED SPECIES
grey squirrels outcompete red squirrels - POLLUTION
oil shipping has accidental discharge/ oil floats prevents oxygenation of water/ animals break through water covered in oil
Define conservation
sensible management of biosphere to maintain habitats and enhance biodiversity while allowing human activity
10 methods of conservation
1) PROTECTING HABITAT PROTECTS SPECIES
- nature reserves, improves and maintains habitat
2) TRADE RESTRICTION
- eg ivory
3) GENE BANKS
- breeding program, records mating
4) SPERM BANKS
- store important genes, use this rather than moving animals
5) SEED BANKS
- seeds for plant reproduction
6) RARE BREED SOCIETY
- maintain older varieties
7) SPECIES REINTRODUCTION
- if conditions favourable
8) EDUCATION
- increase public awareness
9) LEGISLATION
- imposed measures to protect habitat
10) ECOTOURISM
- mass travel= harmful, employ locals, educate visitors
Why should we conserve?
- species vulnerable
- ensures conservation of gene pools
- ethical reasons
- agriculture and horticulture
- natural selection prevents extinction
- potential medical uses
usually plants
new drugs
extinction could mean they aren’t found
Examples of agricultural exploitation?
- agriculture essential for food production
- conflicts with maintaining habitat
- removal of hedgerows
- larger fields for monoculture
- crop rotation
if same then roots reach same level so take same minerals from same depth - overgrazing- hooves compact soil so roots can’t penetrate
Why does deforestation occur?
- timber for building
- farming, biofuels, cattle
- high value tress targeted
- new roads built
Consequences of deforestation
-soil erosion
heavy rain removes topsoil
- of uplands causes low land flooding
- stops carbon cycle so reduces quality of soil
- less rainfall as H20 not returned to atmosphere
- habitat loss
- less photosynthesis- more CO2
How are forests managed?
-cut and burn small areas
- grow crops on soil fertilised by ash
- sustainable replanting
- COPPICING
tree trunk cut leaving stool
shoots emerge and thicken
- SELECTIVE CUTTING
valuable on steep slopes
maintain nutrients
minimise soil washed away
- trees grow optimum distance apart
- control pests/ diseases
- cut similar no. of tress each year
What is over fishing?
- fish pop is dramatically decreasing
- nets with small holes catch small fish before sexually mature leaving fewer to reproduce
8 methods to combat overfishing
1) EXCLUSION ZONES
- areas for fish to breed
- fishermen lose income
2) REMOVING SUBSIDIES
- stop encouraging fishermen to catch fish
- loss of income
3) QUOTAS
- reduce fish caught
- often caught, die, thrown back as quota caught
4) REDUCE VESSELS
- fewer fish caught
- loss of jobs
5) REDUCE FISHING TIMES
- fewer fish caught
- sporadic income
6) CONTROL MESH SIZE
- smaller fish not caught- can reproduce
- adult fish caught= less breeding
7) EATING MSC FISH
- caught in sustainable way
- still caught, criticised
8) EATING NON-TRADITIONAL FISH
- COD etc caught less
What are the problems with fish farming?
- disease spreads easier- spreads to wild fish- need lots of antibiotics
- pollution- fish excreter, fertiliser= EUTROFICATION
How many planetary boundaries are there? what are they?
9
1) climate change
2) biosphere integrity
3) land use
4) biochemical flows
5) ozone
6) ocean acidifcation
7) freshwater
8) aerosol
9) novel entities
What is the climate change boundary? What state is it in?
CROSSED
high CO2, high temps
affects wind patterns, ocean currents, sea level
COP21= agree to combat climate change
What is the biosphere integrity boundary? What state is it in?
CROSSED
habitat destruction, too few left= extinct
monitor biodiversity, limit fishing, conservation
What is the land use boundary? What state is it in?
CROSSED
natural ecosystems become urban, exporting means not locally used
grow more efficient crops, concentrate growth to most productive areas
What is the biochemical flows boundary? What state is it in?
CROSSED
balance chemical elements disrupted in natural cycles
results in eutrophication, acidification
What is the ozone boundary? What state is it in?
AVOIDED
chlorinated and brominated hydrocarbons
‘hole’ in ozone= more UV= DNA mutation
chlorinated and brominated hydrocarbons phased out
What is the ocean acidification boundary? What state is it in?
AVOIDABLE
atmospheric CO2 dissolves in oceans
pH of O2 decreases, gas exchange less efficient
prevent increase in atmospheric CO2
What is the freshwater boundary? What state is it in?
AVOIDABLE
limit water volume taken from rivers
results in desertification, rivers fail to reach sea, more extreme temps
drip immigration, 3 R’s, stop irrigating non-food crops
What is the aerosol boundary? What state is it in?
NOT QUANTIFIED
effects depend on physical and chemical nature, minute particles in atmosphere
blocks sunlight, lower temp, increase floods
What is the novel entities boundary? What state is it in?
NOT QUANTIFIED
synthetic organic pollutants, radioactive materials
irreversible effects
DDT is banned
