Biodiversity and Ecosystems


Human Population Explosion

- biodiversity is the variety of all the different species of organisms on Earth, or within an ecosystem

- high biodiversity helps ensure the stability of ecosystems by reducing the dependence of one species on another for food, shelter and the maintenance of the physical environment

- humans reduce the amount of land available for other animals and plants by building, quarrying, farming and dumping waste

- the future of the human species on Earth relies on us maintaining a good level of biodiversity, many human activities are reducing biodiversity and only recently have measures been taken to address the problem

- rapid growth in the human population and an increase in the standard of living means that increasingly more resources are used and more waste is produced

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Land and Water Pollution

- unless waste and chemical materials are properly handled, more pollution will be caused 

- pollution can occur on land, from landfill and from toxic chemicals such as pesticides and herbicides, which may also be washed from land to water

- pollution can occur in water from sewage, fertilisers, or toxic chemicals

- pollution kills plants and animals, which can reduce biodiversity

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Air Pollution

- unless waste and chemical materials are properly handled more pollution will be caused

- pollution can occur in the air from smoke and from acidic gases

- air pollution kills plants and animals, which can reduce biodiversity

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Deforestation and Peat Destruction

- large-scale deforestation in tropical areas has occurred to provide land for cattle and for rice fields and to grow crops for biofuels

- the destruction of peat bogs and other areas of peat to produce garden compost reduces the area of this habitat and thus the biodiversity associated with it

- the decay or burning of peat releases carbon dioxide into the atmosphere

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Global Warming

- levels of carbon dioxide and methane in the atmosphere are increasing and contribute to global warming

- biological consequences of global warming include loss of habitat when low-lying areas are flooded by rising sea levels

- changes in the distribution patterns of species in areas where temperature or rainfall has changed, and changes to the migration patterns of animals 

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Impact of Change

- environmental changes such as availability of water, temperature, and atmospheric gases affect the distribution of species in an ecosystem

- these changes may be seasonal, geographic, or caused by human interaction

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Maintaining Biodiversity

- scientists and concerned citizens have put programmes in place to reduce the negative effects of humans on ecosystems and biodiversity

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Trophic Levels and Biomass

    level 1- producers (plants and algae)

    level 2- primary consumers (herbivores)

    level 3- secondary consumers (carnivores who eat herbivores)

    level 4- tertiary consumers (carnivores who eat secondary consumers)

- apex predators are carnivores with no predators 

- decomposers break down dead plant and animal matter by secreting enzymes into the environment, small soluble molecules then diffuse into the microorganisms

- pyramids of biomass can be constructed to represent the relative amount of biomass at each level of a food chain, trophic level 1 is always at the bottom of the pyramid

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Biomass Transfers

- producers are mostly plants and algae that transfer about 1% of the incident energy from light for photosynthesis

- only approximately 10% of the biomass from each trophic level is transferred to the level above it

- losses of biomass occur because not all the ingested material is absorbed- some is egested as faeces, some absorbed material is lost as waste products, such as carbon dioxide and water in respiration and water and urea in urine, and large  amounts of glucose are used in respiration

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Factors Affecting Food Security

- food security is having enough food to feed a population

- factors affecting food security include:

    increasing birth rates

    changing diets in developed countries resulting in scarce food resources being transported around the world

    new pests and pathogens affecting farming

    environmental changes afecting food production

    the cost of agricultural inputs 

    conflicts affecting access to water or food

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Making Food Production Efficient

- the efficiency of food production can be improved by restricting energy transfer from food animals to the environment

- this can be done by limiting their movement and by controlling the temperature of their surroundings

- some animals are fed high in protein foods to increase growth

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Sustainable Food Production

- fish stocks in the oceans are declining, it is important to mainain fish stocks at a level where breeding continues or certain species may disappear altogether

- control of net size and the introduction of fishing quotas play important roles in conservation of fish stocks at a sustainable level

- modern biotechnology techniques enable large quantities of microorganisms to be cultured for food

- the fungus fusarium is useful for producing mycoprotein, a protein-rich food suitable for vegetarians. The fungus is grown on glucose syrup, in aerobic conditions and the biomass is harvested and purified

- genetically modified bacteria produce drugs such as insulin on an industrial scale

- genetically modified crops would provide more food or food with an improved nutritional value

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