Unit 2: Section 6


Studying Biodiversity

Biodiversity - The variety of living organisms in an area Species - A group of similar organisms able to reproduce to give fertile offspring Habitat - The area inhabited by a species. It includes the physical factors, like the soil and temperature range, and the living (biotic) factors, like availability of food or the presence of predators Habitat diversity - The number of different habitats in an area. For example, a coastal area could contain many different habitats - beaches, sand dunes, mudflats, salt marshes etc Species diversity - The number of different species and the aabundance of different species in an area Genetic diversity - The variation of alleles within a species (or a population of a species)

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Studying Biodiversity

Sampling: Choose an area to sample - a small area within the habitat being studied. Count the number of individuals of each species. How you do this depends on what you're counting, for example: For plants you'd use a quadrat For flying insects you'd use a sweepnet For ground insects you'd use a pitfall trap For aquatic animals you'd use a net Repeat the whole process - take as many samples as possible. This gives a better indication of the whole habitat. Use the results to estimate the total number of individuals or the total number of different species in the habitat being studied. When sampling different habitats and comparing them, always use the same sampling technique. To avoid bias, the sample should be random.

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Studying Biodiversity

Species richness and species evenness affect biodiversity Species richness - The number of different species in an area. The higher the number of species, the greater the species richness. It's measured by taking random samples of a habitat and counting the number of different species. Species evenness - A measure of the relative abundance of each species in an area. The more similar the population size of each species, the greater the species evenness. It's measured by taking random samples of a habitat, and counting the number of individuals of each different species.

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Studying Biodiversity

Simpson's Index of Diversity Species present in a habitat in very small numbers shouldn't be treated the same as those with bigger populations. Simpson's Index of Diversity takes into account both species richness and species evenness. Simpson's Index of Diversity is always a value between 0 and 1. The closer to 1 it is, the more diverse the habitat. The greater the species richness and evenness, the higher the number.

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Global Biodiversity

Global biodiversity - The total number of species on Earth Named species - Scientists have named between 1.5 and 1.75 million species. This figure isn't exact because there's no central database of all species and some scientists have different opinions about the classification of certain species. Unnamed species - Scientists agree that a large proportion of the species on Earth have not been named - many species are undiscovered, or are known but haven't yet been named. Scientists have different idea about the total number of species on Earth because: Different scientists have used different techniques to make their estimates. Relatively little is known about some groups of organisms - there could be many more than we think. Biodiversity varies in different parts of the world - the greatest diversity is near the equator and it decreases towards the poles. Tropical rainforests are largely unexplored - this might mean current estimates of global biodiversity are too low.

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Global Biodiversity

Climate change affects biodiversity Climate change is the variation in the Earth's climate It occurs naturally, but the scientific consensus is that the climate change we're experiencing at the moment is caused by humans increasing emissions of greenhouse gases Greenhouse gases cause global warming (increasing global average temperature), which cause other types of climate change, e.g. changing rainfall patterns. Climate change will affect different areas of the world in different ways - some places will get warmer, some colder, some wetter and others drier. All of these are likely to affect global biodiversity: Most species need a particular climate to surive. A change in climate may mean that an area that was previously inhabitable becomes uninhabitable, and vice versa. This may cause an increase or decrease in the range of some species. This could increase or decrease biodiversity. Some species may be forced to migrate to a more suitable area, causing a change in species distribution. If there isn't a suitable habitat to migrate to, the species is a plant and can't migrate, or if the change is too fast, the species may become extinct.

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Global Biodiversity

Climate change affects the spread of disease: The ranges of some insects that carry disease might become greater, e.g. as areas become warmer and wetter insects like mosquitos, which can carry malaria, will spread into areas that were previously uninhabitable, bringing the disease with them. This change in distribution could lead to an increase in biodiversity, though the spread of diseases could reduce biodiversity - with some species suffering population decline, or even extinction. Warmer and wetter conditions may also encourage the spread of fungal diseases. This could also lead to an increase or decrease in biodiversity. Climate change affects agricultural patterns: Land that was previously unsuitable becomes available for agriculture; areas of that were too hot or too dry before to support much biodiversity can be farmed, increasing biodiversity Different crops need different conditions so, as the climate in an area changes, so will the crops grown. This could disrupt food chains - some existing species will be left without a source of food, and new food sources will be provided for other species.  Extreme weather events and unexpected conditions, such as a flood or a drought might results in crop failure.

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Importance of Biodiversity

Maintaining biodiversity is important for economic reasons: Food and drink - plants and animals are the source of almost all food and some drinks Clothing - A lot of fibres and fabrics are made from plants and animals Drugs - Many are made from compounds from plants Fuels - We use a number of organisms to produce renewable fuels, including ethanol and biogas. Foddil fuels are non-renewable, so other sources are of major economic importance Other industrial materials - A huge variety of other materials are produced from plant and animal species, including wood, paper, dyes, adhesives, oils, rubber and chemicals such as pesticides.

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Importance of Biodiversity

Maintaining biodiversity is important for ecological reasons: The loss of just one species can have a negative effect, such as: Disruption of food chains Disruption of nutrient cycles Loss of habitats Habitat destruction can also affect climate Maintaining biodiversity is important for ethical reasons: Many believe organisms have a right to exist - they shouldn#t become extinct as a result of our activities Some people believe we have a moral responsibility to conserve biodiversity for future human generations. There are also religious and spiritual reasons for conservation - harmony with the natural world is important to many beliefs and philosophies

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Importance of Biodiversity

Maintaining biodiversity is important for aesthetic reasons: Areas rich in biodiversity provide a pleasant, attracive environment that people can enjoy. The more biodiversity in an area the more visitors the area is likely to attract - this also has economic advantages. Maintaining biodiversity is important to agriculture: Pollinators - Many fruit and vegetable crops are pollinated by insects such as bees and butterflies. The higher the diversity of insects the more pollinators there are. A source of food - Many species are used as food sources for humans and livestock. The more different species there are the more possible sources there are to choose from. Pest control - A number of animals like frogs, birds and hedgehogs are natural predators of crop pests like slugs. The more of these organisms there are the less pests there will be. Protection against disasters - The majority of our food comes from only a few species of plants - if a disease or pest affects these few, our food supply is at risk. New varieties - Plant varieties are needed for cross-breeding. Wild plants can be bred with domesticated plants to produce new varieties with improved characteristics.

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Conservation and Biodiversity

In situ conservation:

  • Keeps species in their natural habitat - on site
  • Methods include:
  • Establishing protected areas such as national parks and nature reserves - habitats and species are protected in these areas by restricting urban development, industrial development and farming.
  • Controlling or preventing the introduction of species that threaten local biodiversity. For example, grey squirrels are not native to Britain. They compete with the native red squirrel and have caused a population decline. So they're controlled in some areas.
  • Protecting habitats - e.g. controlling water levels to conserve wetlands and coppicing (trimming trees) to conserve woodlands. This allows organisms to continue living in their natural habitat.
  • Restoring damaged areas - such as a coastline polluted by an oil spill.
  • Promoting particular species - this could be by protecting food sources or nesting sites.
  • Giving legal protection to endangered species
  • The advantage is that both species and habitat can be conserved.
  • Large poplations can be protected and it's less disruptive.
  • It can be difficult to control some factors that are threatening a species.
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Conservation and Biodiversity

Ex sit conservation:

  • Protecting a species by removing part of the population from a threatened havitat and placing it in a new location. Often a last resort.
  • Methods include:
  • Relocating an organism to a safer area.
  • Breeding organisms in captivity then reintroducing them to the wild when they are strong enough.
  • Botanic gardens are controlled environments used to grow a variety of rare plants for the prposes of conservation, research, display and education. Endangered plant species as well as species that are extinct in the wild can be grown and reintroduced into suitable habitats.
  • Seed banks - seeds can be frozen and stored in seed banks for over a century without losing their fertility. Seed banks provide a useful source of seeds if natural reserves are destroyed, for example by disease or other natural disasters.
  • The advantages are that it can be used to protect individual animals in a controlled environment. It can also be used to reintroduce species that have left an area.
  • Only a small number of individuals can be cared for, and it can be difficuly and expensive to create and sustain the right environment.
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Conservation and Biodiversity

Rio Convention on Biodiversity:

  • Aims to develop international strategies on the conservation of biodiversity and how to use animal and plant resources in a sustainable way.
  • The convention made it part of international law that conserving biodiversity is everyone's responsibility.
  • It also provides guidance to governments on how to conserve biodiversity.

CITES agreement:

  • CITES (Convention on International Trade in Endangered Species) is an agreement designed to increase internatinoal cooperation in regulating trade in wild animal and plant specimens.
  • The memeber countries all agreed to make it illegal to kill endangered species.
  • The agreement helps to conserve species by limiting trade through licensing, and by making it illegal to trade in products made from endangered animals.
  • It's also designed to raise awareness of threats to biodiversity through education.
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Conservation and Biodiversity

Environmental Impact Assessments (EIA):

  • An assessment of the impact a deveoping project might have on the environment. It involves:
  • Estimating biodiversity on the project site and evaluating how the development might affect biodiversity.
  • Identifying ways that biodiversity could be conserved.
  • Identifying threatened or endangered species on the project site and the laws relating to their conservation.
  • Deciding on planning stipulations - measures that will have to be implemented if the project proceeds.
  • Local authorities are often under pressure from conservationists who argue that developments damage the environment and disturb wildlife - they feel that habitats should be left alone.
  • Environmental impact assessments ensure that decision makers consider the environmental impact of development projects - they're used by local authorities to decide if and how projects will proceed.
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