Human Impact on Environment Flashcards
define extinction
complete loss of species
reasons why species become extinct
natural selection
non contingious population
loss of habitat
deforestation
loss of hedgerows
drainage of wetlands
over hunting by humans
competition- interspecific (alien species)
pollution
define conservation
is the planned management of ecosystems to
enhance biodiversity and protect gene pools.
how can conservation be achieved
Protecting habitats e.g. SSSIs and Nature Reserves
International co-operation restricting trade in endangered species and their parts
e.g. ivory and the products of whaling (look at the CITES web site)
Gene & Sperm banks
Seed banks (Kew Gardens)
Rare breed societies
Species reintroduction e.g. the red kite in mid-Wales
International organisations which organise publicity to educate and increase public
awareness e.g. WWFN
Legislation e.g. the EU Habitats Directive
Ecotourism, which aims to educate, conserve and contribute to local economies
what is a monoculture
is the growth of large numbers of
genetically identical crop plants in a defined area.
disadvantage of monoculture
provide only one type of habitat- which reduces biodiversity
advantage monoculture
Monocultures reduce soil fertility as roots grow to the same length and extract minerals from the same depth – this increases the need for
chemical fertilisers.
how is pesticide used by farmers
Plants of the same species, grown so close together,
are also susceptible to the same pests and diseases,
which are able to pass from plant to plant rapidly.
define pesticide
include chemicals which kill or inhibit the
growth of weeds (herbicides), fungi (fungicides) and
insects (insecticides).
define chemical fertiliser
include the elements NPK and increase plant growth.
disadvantage of overgrazing
cause soil compaction, reducing air spaces and inhibiting nitrogen
fixing and nitrifying bacteria – leading to a loss of soil fertility
Water is also unable to penetrate compacted soil and grass growth is inhibited.
define deforestation
is the removal of trees to use as timber or fuel or to
repurpose the land use for agriculture or building.
consequences of deforestation
Soil erosion
Lowland flooding
Desertification
Habitat loss
Decrease in biodiversity
Climate change
what is coppicing
tree trunks are cut at their base, leaving a stool (stump) a few
centimetres above the soil. New shoots grow from the stool which can be harvested
at different diameters for different purposes e.g. building, fencing or fire wood.
ways to manage forest woodland
Selective cutting
coppicing
Long rotation time
disadvantage of overfishing
depletes fish stocks. Fish populations may become too low to recover – they
are no longer viable. This also impacts food chains and entire ecosystems.