human impact on the environment Flashcards
outline the potential causes for the extinction of a species
- natural selection
- loss of habitat
- pollution
- overhunting
- new competitors
- non-contiguous populations
what is meant by conservation
maintenance of ecosystems and biodiversity by humans to preserve Earth’s resources
how can conservation be achieved
- protection of habitats
- protection of endangered species
- international cooperation
- species reintroduction
- gene and sperm banks
- seed banks
define what is meant by biodiversity
number of species and number of individuals in each species in a specified region
define what is meant by extinction
natural process where species reproduce less successfully and population numbers decrease until there are none left
give an explanation for natural selection causing extinction
existing species don’t have the ability to survive in a changing environment
why does deforestation cause extinction
habitat destruction
reduced food availability
increased risk of predation
why does habitat destruction cause extinction
reduces population sizes so reproduction is less successful
why does loss of hedgerows cause extinction
mammals unable to move from one area to another safely
why does pollution cause extinction
- neurotoxins can be ingested in food
- oil leaks contaminate drinking water
- oil floats and prevents oxidation
why does competition from domestic animals cause extinction
species that is less well adapted may get fewer resources that both species need
why does hunting and collecting cause extinction
overfishing
animals killed for food
use of animal body parts
what does SSSI stand for
sites of special scientific interest
how do nature reserves and SSSI’s enhance biodiversity
many animals and plants survive through symbiotic or predatory relationships with other species
how do restrictions on trade enhance biodiversity
reduces impact of transport and pollution
no introduction of pathogens and invasive species
how do zoo breeding programmes enhance biodiversity
gene diversity can be increased by deliberate choice of parents
how do sperm banks / seed banks enhance biodiversity
- rather than moving animals, sperm can be sent around the world to be used in breeding programmes
- plants grown reproduce and another generation of seeds is collected
how to reintroductions enhance biodiversity
increase number of species or places where species can be found
outline why conservation of species is important
- ethical reasons
- agriculture and horticulture
- if environment changes, some alleles will provide an advantage to the individuals that carry them
- potential medical uses
how do pesticides increase production
- insecticides kill pests that eat and damage crops
- herbicides kill weeds that cause competition for crops
what effects do pesticides have on the environment
contamination of surrounding soil and water sources, causing loss of biodiversity
how do artificial fertilisers increase production
replaces minerals lost from agricultural ecosystems ensuring yields remain high
what effects do artificial fertilisers have on the environment
chemical fertilisers can leach out into nearby waterways causing eutrophication
how does removal of hedges increase production
makes land easier and cheaper to work
how does monoculture increase production
increased use of machinery and decreased labour costs mean continuous cropping of one crop bring greater economic returns per unit area of land
what effects does monoculture have on the environment
reduces species and genetic diversity of all plants and also animals because there are fewer niches available
outline the reasons for deforestation
- timber used for building, fuel, paper
- land cleared for farming
- high value trees may be targeted and damage other trees in the process
- new roads built
outline the consequences of deforestation
- soil erosion as roots bind soil together
- causes lowland flooding
- no plants left and water evaporates from the soil
- less rainfall as no water to evaporate from the soil
- habitat loss and reduction in biodiversity
- reduces removal of CO2 from the atmosphere
explain coppicing
- tree trunk cut leaving stool
- new shoots emerge and form poles which can be cut in rotation
- increases woodland biodiversity as more light can reach the ground
explain selective cutting
- felling only some trees
- valuable on steep slopes as reduces soil erosion
- helps maintain nutrients in forest soil
- minimises amount of soil washed into nearby waterways
explain long rotation time as a method to manage forests
- many years left between harvesting adjacent areas of forest
- increases sustainability
- develops a variety of habitats
what steps can be taken to improve the efficiency of forestry
- plant trees optimum distance apart to reduce intra-specific competition
- control pests and disease so fewer trees need to be felled
- cut similar number of trees each year to maintain forest ecosystem
why is the preservation of native woodlands so important
- maintain and enhance biodiversity
- there is a need to plant more native species to provide a wide range of habitats for the great variety of species that live there
explain how overfishing has led to a loss of biodiversity
- young fish caught before they are sexually mature so fewer individuals to reproduce
name the strategies to combat over-fishing
- exclusion zones
- removing subsidies
- quotas
- reducing vessels
- reducing fishing time
- controlling mesh size
outline the advantages of exclusion zones
- allows fish to reproduce
- enhances biodiversity
outline the disadvantages of exclusion zones
local fisherman lose income
outline the advantages of removing subsidies
would stop encouraging fishermen to catch fish
outline the disadvantages of removing subsidies
fishermen lose income and jobs
outline the disadvantage of quotas
some fish thrown back when quota is met
what is meant by a fishing quota
set number of fish allowed to be brought back to shore
why are diseases common on fish farms and why do treatments lead to environmental problems
- fish kept packed together so diseases easily transmitted
- huge doses of antibiotics needed
- pesticides toxic to other organisms
outline the negative effects of fish farming on the environment
- pollution
- escaped fish - may outcompete wild fish
- resource use - fishfeed made from other fish
- environmental toxins released
- environmental degredation - salinisation of soil and ground water
name the positive benefits of fish farming
- food security
- employment
- affordable
