4.2.1 Biodiversity Flashcards
What are endangered and critically endangered species?
Endangered species: Population critically low due to humans, so species is close to being extinct
Critically endangered: Likely to go extinct, numbers are not sustainable and too low for survival of the species
How are humans reducing biodiversity?
- deforestation: permanent removal of large areas of forest to provide wood for building + fuel. Also to create space for roads/building/agriculture
- agriculture: land has to be farmed for feeding growing population - land cleared and single crop grown (monoculture)
- climate change: much evidence that greenhouse gases (e.g. CO2 from burning fossil fuels) increases global temperatures
How does deforestation reduce biodiversity?
- directly reduces number of trees present in an area
- if only a specific type of tree is felled, species diversity is reduced
- reduces no. of animal species present in the area - destroys habitat + food sources
- animals forced to migrate to other areas to ensure survival
How does agriculture reduce biodiversity?
- removal of hedgerows to allow use of large machinery - reduces no. plant species + destroys animal habitats (blackbirds, hedgehogs, mice, invertebrates)
- use of pesticides - destroys pest species (insects) + indirectly destroys food source of other organisms
- use of herbicides - reduces species diversity of weeds - important food source may be removed
- use of monoculture - enourmas effect of lowering biodversity as only one species of plant is present + suports relatively few animal species
- clearing land and selective breeding + cloning reduces genetic variation
What other disadvantages are there of using chemicals in agriculture?
- may kill other species
- effect food chains/webs
- may cause human harm due to bioaccumulation in food chains/webs
What are the advantages of hedgerows?
- food and shelter important to species
- control water levels + run off
- pest control as predators live in them
- pollination of crops by insects
What is the greenhouse effect and how are humans making it worse?
After the sun hits the earth it is reflected back, but with a longer wavelength - some of it gets reflected back again by the atmosphere
Worsened By
- burning fossil fuels (releasing CO2)
- deforestation (removing trees releases CO2)
- cattle + rice fields (produce methane)
How will climate change effect the earth?
- melting polar ice caps could lead to extinction of plant + animal species living there
- rising sea levels from melting ice could lead to flooding of low-land areas, reducing no. terrestrial habitats
- rising sea levels from melting ice could lead to seawater flowing up rivers, reucing no. habitats of freshwater plants + animals
- high temperatures + less rainfall would result in plant species failing to survive - leading to drought resistant species becoming more dominant, leading to loss of animal species
- insect life cycles + populations will change - insects are key pollinators, so if range of insects changes it could affect the lives of plants causing extinction
What are the consequences of climate change on spread of disease?
- disease of domestic animals (e.g. blue tongue in cattle) will increase due to vectors being able to survive winters
- pests usually killed by frost in winter may survive, leading to increased plant diseases + fungal infections
- female mosquitos carry parasites they can pass to humans when feeding, but can’t survive below 10°c and need high humidity - increased risk due to warmer temps
What are the consequences of climate change on plants + animals?
- mangrove swaps depend on their roots being out of water to obtain oxygen - if sea levels rise mangrove swamps will be lost
- some species of fish stop growing at a certain remperature - this could stop growing before reproductive age or of a sufficent weight to survive winter
- climate change would increase rain fall in parts of the world + decrease in others - selective breeding means low genetic variation so cannot adapt to change in rainfall
Why is it important to maintain biodiversity?
- aesthetic reasons
- economic reasons
- ecological reasons
What are the aesthetic reasons for maintaining biodiversity?
- enrichment of lives (e.g. relaxing on beach/ walking in woodland)
- provides inspiration for people (e.g. musicians + writers)
- can increase patiens recovery from stress + injury
What are the economic reasons for maintaining biodiversity?
- soil erosion + desertification reduces a countries ability to grow crops - rely on other countries
- non-sustainable removal of resources (e.g. timber) will lead to collapse of industry
- species with potential economic importance may become extinct before discvoery (may have medical or chemical value)
- ecotourism areas are attractive + promote tourism, providing money + jobs to local community
- continous monoculture results in depletion of mineral ions - crops more likely to be vulnerable to insects/microorganisms/plant competitors - farmer has to buy pesticides/herbicides + fertilisers
- a change in condition or disease can destroy a crop without high biodiversity providing abiotic stresses
- greater diversity = greater potential for manufacture of different products in the future (potential for money + jobs)
- plant varieties needed cor cross breeding - leads to better characteristics (e.g. diseases resistance or increased yield)
What are the ecological reasons for maintaining biodiversity?
- organisms are poart f a food chain - interdependant on others for survival (e.g. food source, habitat or pollination)
- keystone species - some species play a key role in maintaining structure of ecological community - have a disproportionally large effect on their environment
- genetic variation leads to evolution, allowing adaptations to occur with changing climate/conditions - without it whole crops + organisms could be destroyed
What are ‘in situ’ and ‘ex situ’ forms of conservation?
In situ: Conservation of a species in its natural habitat
Ex situ: Conservation of species by removal of the organism from its natural habitat
