Factors affecting Biodiversity Flashcards
Why is maintaining biodiversity essential ?
- For preserving a balanced ecosystem for all organisms
- all species are interconnected within an ecosystem the removal of one species can have a profound effect on others for eg. Can lead to a loss of another’s species food source or shelter
Has the human population increased or decreased since the 1800s ?
Increased
Why has population increased ?
Improved technology leading to an abundance of food = increase in birth rate
Improved medicine, hygiene and health care = decrease in death rate
Why are humans interfering with our surrounding biodiversity ?
To create enough space for housing , industry and farming to support the increasing population
What are the main problems occurring as a result of ?
- deforestation
- agriculture
- climate change
Can deforestation occur naturally ?
Yes
As a result of forest fires caused by lighting or extreme heat and dry weather
How does deforestation affect biodiversity ?
- it directly reduces the number of trees present in an area
- if only a specific type of tree is felled the species diversity is reduced
- reduces the number of animal species present in an area as it destroys their habitat including their food source and home —> this in turn reduces the number of other animal species that are present by reducing or removing their food source
- animals are forced to migrate to other areas to ensure their survival —> may result in the biodiversity of neighbouring areas increasing
Why do farmers selectively grow species and read animals ?
- They select characteristics that give a high yield thus only grow certain species
- the selection of only a few species greatly reduces the biodiversity of an area
In order to be economically viable what are the techniques that farmers use to increase their desired species ?
Deforestation - to increase the area of land available for growing crops or rearing animals
Removal of hedgerows - as a result of mechanisation, farmers remove hedgerows to enable them to use large machinery to help them plant , fertilise and harvest crops
- also frees up extra land for crop growing —> reduces the number of plant species present in an area and destroys the habitat of animals such as blackbirds,hedgehogs, mice and many invertebrates
Use of chemicals such as pesticides and herbicides - pesticides used to kill pests that would eat the crops or live on the animals —> this reduces species diversity directly as it destroys the pest species and indirectly by destroying the food source of other organisms
Herbicides are used to kill weeds - a weed is any plant growing in an area where it is not wanted
- weeds are destroyed as they compete with the cultivated plants for light , minerals and water
- by destroying weeds plant diversity is reduced directly and animal diversity may also be reduced not the removal of an important food source
- monoculture - many farms specialise in the production of only one crop with many acres of land being used for the growth of one species
- has an enormous local effect In lowering biodiversity as only one species of plant is present
- as relatively few animal species will be supported by only one type of plant this results in low overall biodiversity levels
- the growth of vast oil palm plantations is one of the leading causes of rainforest deforestation leading to a loss of habitat for critically endangered species like a rhino
Define habitat fragmentation
Habitats are divided into small acres - populations living within these separated habitat fragments are more likely to suffer from inbreeding or local extinction
What is the IPCC ?
Intergovernmental panel on climate change
What were the key findings of the IPCC report ?
- the warming trend over the last 50 years ( about 0.13°C per decade ) is nearly twice that for the previous 100 years
- average amount of water vapour In the atmosphere has increased since the 1980s over the land and ocean . The increase is broadly consistent with the extra water vapour that warmer air can hold
- since 1961 the average temperature of the global ocean down to depths of 3 Km has increased
- the ocean has been absorbing more than 80% of the heat added to the climate system, causing seawater to expand and contribute to sea-level rise
- the global average sea level rose by an average of 1.8mm per year from 1961 to 2003
- there is high confidence that the rate of observed sea level rise increased from the 19th to the 20th century
- average arctic temperatures have increased at almost twice the global average rate in the past 100 years
- mountain glaciers and snow cover have declined on average in both hemispheres
- widespread decreases in glaciers and ice caps have contributed to sea level rise
- long term upward trends in the amount of precipitation have been observed over many regions from 1900-2005
Why is it important to enable our understanding of climate change ?
- significant quantities of data have been developed charting changes to the earths climate over time
- requires an enormous international co-operating effort over many years
- only on the basis of reliable , irrefutable evidence that decisions of an international significance can take place
- decisions made now may have far reaching consequences for the populations of individual countries or continents today as well as far reaching global Implications for the future
What does global warming refer to in simple terms ?
Rise in earths mean surface temperature
If global warming continues biodiversity will be affected.
What are some examples of this ?
- the melting of the polar ice caps could lead to the extinction of the few plant and animal species living in these regions
- some species of animals present in the arctic are migrating further and further north to find favourable conditions as their habitat shrinks
- increasing global temperatures would allow temperate plant and animal species to live further north than currently
- rising sea levels from melting ice caps and the thermal expansion of oceans could flood low lying land , reducing the available terrestrial habitats
- saltwater would flow further up rivers, reducing the habitats of freshwater plants and animals living in the river and surrounding areas
- higher temperatures + less rainfall would result in some plant species failing to survive leading to drought resistant species becoming more dominant
- the loss of non drought resistant species dependent on them as a food source
- these would be replaced by other species that feed on the xerophytes
- insect life cycles and populations will change as they adapt to climate change
- insects are key pollinators of many plants so in the range of an insect changes it could affect the lives of the plants it leaves behind causing extinction
- as insects carry many plant and animal pathogens if tropical insects spread this in turn could lead to the spread of tropical diseases towards the poles
