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3.6 - Human impact on the environment - Coggle Diagram
3.6 - Human impact on the environment
Extinction
Species may become endangered or extinct from:
Natural selection
due to changing populations
Non-contiguous populations
- Populations which are too small with insufficient genetic diversity to ensure a healthy an viable increase in number
Loss of habitat
- Deforestation, drainage of wetlands and loss of hedgerows
Overhunting by humans
- Overfishing etc
Competition
- from alien species
Pollution
- Due to human activity.
Conservation
Protection, preservation, management and restoration of natural habitats.
Aim to maintain species and genetic biodiversity while allowng human activity to continue.
Protecting habitats
Gene and sperm banks
Seed banks
Rare breed societies
International organisations
Legislation
maintaining biodiversity by conservation is essencial for protecting potential sources of news crops and pharmaceuticals
Agricultural exploitation
Intensive farming
has seen an increase in the use of chemical fertilisers, pesticides and herbicides
Mechanisation requires larger fields to accommodate large machinery; reduction in the number of hedgerows
Large fields are used to grow
monocultures
, in which a single crop is grown on a large scale.
Monocultures
Provide only one type of habitat, reduces biodiversity.
Reduce soil fertility, increases the need for chemical fertilisers.
Plants of the same species, grown close together are also susceptible to the same pests and diseases, which are able to pass from plant to plant rapidly. To conbat farmers use
more pesticides
Monoculture - The growth of large numbers of genetically identical crop plants in a defined area
Pesticides - Include chemicals which kill or inhibit the growth of weeds, fungi or insects
Chemical fertilisers - inclue the elements NPK and increase plants growths
Overgrazing
Cause
soil compaction,
reducing air spaces and inhibiting nitogen fixing nitrifying bacteria
Leading to loss of soil fertility
water is unable to penetrate compacted soil and grass growth is inhibited
Farming in the future
Organic Farming
- reducing the need for chemical fertilisers and pesticides and allows for crop rotation on smaller fields
-
Set-aside schemes
- farmers manage their farms for biodiverity, land is set aside for conservation and wildlife.
Legislation
- loss of hedgrows has been reversed. Hedgerows provide habitias and food sources for insects, birds and small mammals. Nesting sites and act as corridors allowing wildlife to move from area to area safely.
Deforestation
Complete loss of trees in a defined area. The land is used for agriculture, building or infrastructure
Trees are being cut down faster than forests can regenerate.
Soil erosion
Lowland flooding
Desertification
Habitat loss
Decrease in biodiversity
Climate change
Forest management
Managed forestry involves sustainable replanting and regeneration
Coppicing
Trunk cut down to base, leaving stump a few cm above soil
Selective cutting
Long rotation time
Good forest practise includes
planting trees an optimum distance apart
,
controlling the spread of pests and disease
,
controlled timber cutting
and
protection on native woodlands.
Overfishing
Depletes fish stocks. This also impacts food chains and entire ecosystems. commercial fishing employs:
Drift netting
, a net is stretched between two boats, thousands of miles of net are set and often non-target species are caught.
Trawling
, weighted nets are dragged across the ocean floor, this method catches everything and damages the ocean floor, decimating habitats for many miles.
- To preserve fish stocks
Regulated mesh size
Quotas and landing size regulations
Exclusion zones
legislations limiting the size of the fishing fleets or controlling the number ofdays spent at sea.
Fishing alternative, non-traditional, species
Using lines not nets.
Fish Farming
Large-scale, intensive farming where fish are bred and mature in enclosed ponds. Food, predation, disease and parasites are controlled. warm water is used to accelerate growth
Disadvantage
Rapid spread of disease are parasites
, due to high density of farmed pop.
Pesticides bioaccumulate
, causing a reduciton in fertility.
Nitrogenous waste pollution
, leading to eutrophication.
Farmed fish may carry disease and outcompete wild fish.
farmed fish contain
high levels of toxic chemicals
such as methyl mercuty, diocins pesticides and PCB's