7.2, 7.3, 7.5 human impact and food production Flashcards
(33 cards)
biodiversity
a measure of the number and distribution of different species within a particular cosystem
high biodiversity ensures stability of the ecosystem becuase it provides:
more food sources
more nest sites
more habitats
more niches (the position that an organism holds in its environment)
negative effects of humans on biodiversity
pollution from farms and factories
acid rain
global warming and climate change
introduction of non-native species, e.g. grey squirrels
positive effects of humans on biodiversity
laws which protect rainforests
reducing water pollution
restricting public access to sites of speical interest (SSIs)
reducing sheep grazing of uplands
replanting hedgerows and woodlands
reintroduction of native species, e.g. beavers
efforts made to maintain biodiversity and reverse some of the negatives:
recycling of resources—less emissions becuase don’t need to make the same product twice, less waste in landfill where anaerobic decay leads to global warming
breeding programmes
protection/regeneration of habitats
reduction of carbon dioxide emissions
reduction of deforestation
reintroduction of field margins/hedgerows
why do humans require large areas of land?
quarrying
farming
building
waste/landfill
types of pollution
land pollution: toxic substances from factories and landfill sites, herbicides and pesticides
air pollution: greenhouse gases, acidic gases, smoke/particulates
water pollution: toxic substances, fertiliser runoff, sewage, acid rain
toxic substances from factories and landfill sites
land pollution
damage plant roots so less mineral uptake and less growth
less food sources for herbivores
herbicides and pesticides
land pollution
kills plants and insects which reduces biodiversity
greenhouse gases
air pollution
causes gloabl warming, increasing floods, fires and rising sea levels
acidic gases
air pollution
causes acid rain which damages plant leaves which means less photosynthesis
smoke/particulates
air pollution
causes damage to lungs, e.g. asthma
toxic substances in water
water pollution
causes bioaccumulation where toxins build up in top predators and affect cell reactions (metabolism)
fertiliser runoff
water pollution
causes eutrophication where algae multiply and block sunlight to plants
fish die due to lack of oxygen
sewage
water pollution
causes bacteria to multiply and use oxygen for respiration
fish die due to lack of oxygen
acid rain
water pollution
lowers water pH
kills fish by damaging their gills
kills coral by bleaching
eutrophication
farmers add fertilisers to soil to replace mineral ions and keep the soil fertile. these minerals are easily washed into local streams, rivers and ponds
fertiliser enters water, increasing nutrient content
plant and algae growth increases
algae blooms, forming a thick surface layer
sunlight is blocked, causing aquatic plants to die
dead plants leave nutrient-rich material for decay
decomposers decay the dead plants, reducing oxygen levels, fish die bc they can’t respire
bioaccumulation
when chemicals are added to an environment, they can become part of a food chain
the chemicals increase in concentration at each subsequent level of a food chain, becuase as you go up a food chain, diomass decreases as energy is lost but the level of toxin stays the same
so they can reach v high concs in top carnivores, that can become infertile and even die
greenhouse effect explain
heat energy from the sun warms the earth
some of this heat energy is then radiated back into spcae
greenhouse gases in the atmosphere re-radiate some enrgy back to earth
main: methane, co2
effects of greenhouse effect
changes in earths climate: rising temps, increase in sever weather events—droughts, floods, hurricanes, wildfires
rise in sea level: lowland areas may become submerged, habitats will be lost, mass migration of ppl and animals
reduced biodiversity: many organisms will be poorly adapted to changed encironment and their numbers will fall, may become extinct. dur to interdependence whole ecosystems may fail
changes in migration pattersn: seasons may change, habitats/food souces may be lost. birds, insects and mammals may have to change migration patterns
changes in distribution: changes in abiotic facts will mean that some species are better adapted and will expand their range. others will be poorly adapted and their range will shrink
destruction of carbon sinks
peat bogs
deforestation
destruction of carbon sinks: peat bogs
peat forms over thousands of years usually in marshy areas when plant material cannot decay due to the acidity and lack of oxygen
so peat is a massive carbon sinks as it locks up carbon contained in the plant matter (carbon sequestration)
contains many species (venus flytrap, sundew plants, pitcher plants) that aren’t found anywhere else due to unique abiotic conditions
peat used for:
fuel (burnt)
compost in gardens
destruction of carbon sinks: deforestation
cut down huge areas of forests to provide open land for cattle grazing or to use as rice fields to grow crops for use as biofuels
deforestation increases carbon dioxide by:
combustion of wood
less photosynthesis
increased decay
also loss of biodiversity—animals and plants die out due to loss of habitat, food sources; these species masy not have yet been identified and could be destroying sources of new medicines for the furture
food security
having enough food to feed a population. the food must be readily available and provide a balanced diet to avoid malnutrition and disease
threats to food security
rising populations—inceasing birth rates
changing diets—in developed countries, where non-native grown foods are often imported so scarce food resources being transported around the world rather than being available for local populations
conflicts—e.g. war
environmental changes—drought, flooding leads to crop failure and famine
introduction of new pests/pathogens can reduce crop yields
increased cost for equipment—farming becoming more mecanised
