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
