biodiversity and ecosystems

• geographic variation is when the same species vary depending on their location e.g. arctic fox, desert fox and red fox. each of these will have different adaptations suited to where they live.
• biodiversity is the variety of different species of organisms. biodiversity can also refer to an individual ecosystem.
• biodiversity is really important for ecosystems; different animals depend on each other for food and shelter. species also have to maintain the environment e.g. decomposers break down the remains of dead organisms.
• a high level of biodiversity means that there are lots of different species, this makes an ecosystem more stable. having lots means that the ecosystem is less dependent on one species. so if the population of this species falls, it is less likely to affect the whole ecosystem.
• humans have a negative effect on biodiversity. e.g. deforestation. tropical forests contain a very rich biodiversity, however these are being destroyed for many reasons.
• deforestation happens for land e.g. grazing cattle or rice fields, for timber or for the wood to use as fuel.
• due to increasing population, humans are using more of the earth's resources than ever before, this however does mean they are producing more waste which is leading to pollution.
• humans produce lots of sewage containing urine and faeces. in some laces, this sewage is released into nearby waterways. in the UK, sewage is treated before being released however sometimes untreated sewage is accidentally released into rivers or streams.
• rivers and streams can also be polluted with fertilisers from farms. this as well as released sewage can cause dissolved oxygen levels in the waters to fall, this can kill aquatic organisms
• burning coal in power stations can release acidic gases which can cause acid rain. it also produces smoke which can kill plants and animals which reduces biodiversity
• waste can also pollute the land e.g. landfills. landfills destroy habitats for plants and animals. toxic chemicals can also leach out of landfills and pollute the soil. toxic chemicals can sometimes be dumped straight on the land
• humans use land for buildings e.g. shops, houses, farms, quarries and landfills. this means there is less space for animals and plants. the reduction in habitats reduces biodiversity
• peat bogs contain large amounts of dead plant materials. the conditions in the peat mean that decay is very slow. they contain large amounts of trapped carbon.
• peat is used to produce cheap compost for gardens and farms, or sometimes burned to release energy to generate electricity.
• the destruction of peat bogs reduces the area of habitat, reducing the variety of animals, plants and microorganisms that live there.
• once peat has been extracted and used for compost, it begins to decay. this releases large amounts of carbon dioxide into the atmosphere.
• alternatives to compost using peat are very expensive, if farmers turn to peat-free compost, this could increase the price of food
• the earth's temperature has changed in the past, but these were natural changes. now, changes in the temperature is caused by human activities
• carbon dioxide which is released by burning fossil fuels and methane which is released by cows are greenhouse gases. greenhouse gases trap heat in the atmosphere which causes global warming
• thousands of scientific papers have been published on global warming, these have been checked by other scientists before being published. this is called peer-review.
• peer-review helps to detect false claims and make sure that research published in the journals is valid
• reports on climate change in the popular media are not subject to peer-review. this means that reporting on global warming can be oversimplified, inaccurate or biased.
• one of the consequences of global warming is loss of habitats. we see reductions in ice levels in the arctic, this will cause populations of arctic organisms such as polar bears to fall as their habitat is reduced
• as global temperatures rise, animals such as birds and insects may gradually extend their range northwards towards cooler conditions
• mosquitoes carry diseases e.g. malaria. these mosquitoes cannot survive the cold conditions of the UK however if global warming increases temperature too much, the range of these insects may spread to the UK, bringing diseases like malaria with them
• with global warming, the migration patterns of animals may change
• global warming can affect plants. spring plants are flowering earlier due to warmer conditions. as temperatures increase, we may be able to grow crops like grapes in the UK, that require warmer weather.
• with global warming, some parts of the world may become too hot to grow the crops that they need
• to maintain biodiversity, we can use breeding programmes for endangered species. this is a way to encourage more breeding among species that are endangered.
• wetlands have high levels of biodiversity. however recently they have been drained to grow crops. some areas have been protected so they can never be drained. some are also being reflooded.
• the protection and regeneration of rare habitats is important for preserving biodiversity.
• biodiversity is low on farmlands that contain one type of crop. to help increase biodiversity, farmers leave a strip of land around the crops where wild plants and animals can live. these are called field margins
• farmers can also plant hedgerows between fields. lots of species of plants and animals live in hedgerows. these as well as field margins help preserve biodiversity on farms
• by reducing deforestation and carbon dioxide emissions, governments can educe the loss of biodiversity
• individuals can recycle waste materials to avoid them going to landfill, which destroys habitats and land
• trophic means feeding. producers are trophic level 1, primary consumers and level 2, secondary consumers are level 3 and tertiary consumers are level 4.
• apex predators are carnivores with no predators
• when decomposers break down dead remains in the ground, they return mineral ions back into the soil. for this to happen, decomposers secrete enzymes into the environment. the enzymes digest the dead materials and the small soluble food molecules then diffuse back into the decomposer
• trophic levels tells us an organisms position on a food chain. we can measure the mass of the organisms at each trophic level, this is called the biomass.
• dry biomass is more accurate than wet biomass, because the moisture content of organisms can vary widely and produce inaccurate results.