Biology - Topic 7 - Ecology (Environmental Change (Overview (Environmental…
Biology - Topic 7 - Ecology
- the place where an organism lives
- all the organisms of one species living in a habitat.
- the populations of different species living in a habitat.
- non-living factors of the environment such as temperature.
- living factors of the environment.
- the interaction of a community of living organisms (biotic) with the non-living (abiotic) parts of the environment.
Resources to survive
, as well as
(nutrients) from the soil.
(other animals to reproduce with).
with other species (and members of their own)
for the same resources.
Knock-on effects of a change in any environment
In a community,
each species depends on other species
for things such as food, shelter, pollination and seed dispersal - this is called
The interdependence of all the living things in an ecosystem means that
any major change
in the ecosystem can have
all the species and environmental factors are in balance
so that the
ancient oak woodlands.
Abiotic and Biotic Factors
Variation of Abiotic factors in an ecosystem
Carbon dioxide level (for plants)
Wind intensity and direction
Oxygen level (for aquatic animals)
Soil pH and mineral content
Changes in Abiotic factors
A change in the environment
could be an
, e.g. an increase in temperature.
These changes can
affect the sizes of populations
in a community.
This means they can
affect the population sizes of other organisms that depend on them.
animals depend on plants for food
, so a
decrease in a plant population
affect the animal species in a community.
Two examples of changes in abiotic factors which may affect plant populations
A decrease in light intensity, temperature or level of carbon dioxide could decrease the rate of photosynthesis in a plant species.
This could affect plant growth and cause a decrease in the population size.
A decrease in the mineral content of the soil (e.g. a lack of nitrates) could cause nutrient deficiencies.
This could affect plant growth and cause a decrease in the population size.
Variation of Biotic factors in an ecosystem
Biotic factors that might affect organisms in an ecosystem...
New predators arriving
Availability of food
Knock-on effects of changes in Biotic factors
A change in the environment could be the introduction of a new biotic factor, e.g. a new predator or pathogen.
A new predator could cause a decrease in the prey population.
These changes can affect population sizes in a community, which can have knock-on effects because of interdependence.
Organisms, including microorganisms, are adapted to live in different environmental conditions. The features of characteristics that allow them to do this are called adaptations.
Artic animals like the Arctic fox have white fur so they're camouflaged against the snow. This helps them avoid predators and sneak up on prey.
Animals that live in cold places (like whales) have a thick layer of blubber (fat) and a low surface area to volume ratio to help them retain heat.
Animals that live in hot places (like camels) have a thin layer of fat and a large surface area to volume ratio to help them lose heat.
These are ways that organisms behave.
Many species migrate to warmer climates during the winter to avoid the problems of living in cold conditions.
These are things that go on inside an organism's body that can be related to processes like reproduction and metabolism (all the chemical reactions happening in the body).
Desert animals conserve water by producing very little sweat and small amounts of concentrated urine.
Brown bears hibernate over winter. They lower their metabolism, which conserves energy, so they don't have to hunt when there's not much food about/
Adaptations of microorganisms
Some microorganisms such as bacteria are known as extremophiles - they're adapted to live in very extreme conditions.
For example, some can live at high temperatures and others can live in places with a high salt concentration or at high pressure.
Show what's eaten by what
Food chains always start with a producer.
Producers make their own food using energy from the Sun.
Producers are usually green plants or algae - they make glucose by photosynthesis.
When a green plant produces glucose, some of it is used to make other biological molecules in the plant.
These molecules are the plant's biomass - the mass of living material.
Biomass can be thought of as energy stored in a plant.
Energy is transferred through living organisms in an ecosystem when organisms eat other organisms.
Producrs are eaten by primary consumers. Primary consumers are then eaten by secondary consumers and they are eaten by tertiary consumers.
Populations of prey and predators go in cycles
Consumers that hunt and kill other animals are called predators, and their pray are what they eat.
In a stable community containing prey and predators:
The population of any species is usually limited by the amount of food available.
If the population of the prey increases, then so will the population of the predators.
However, as the population of predators increases, the number of prey will decrease.
For example, more grass means more rabbits.
More rabbits means more foxes.
But, more foxes means fewer rabbits.
Eventually, fewer rabbits will mean fewer foxes again.
This up and down pattern continues...
Predator-prey cycles are always out of phase with each other. This is because it takes a while for one population to respond to changes in the other population.
Environmental changes can cause the distribution of organisms to change.
A change in distribution means a change in where an organism lives.
The distribution of bird species in Germany is changing because of a rise in average temperature.
The European bee-eater bird is a Mediterranean species but is now present in parts of Germany.
Availability of Water
The distribution of some animal and plant species in the tropics changes between the wet and dry seasons - i.e. the times of the year where there is more or less rainfall, and so more or less water available.
Each year in Africa, large numbers of giant wildebeest migrate, moving north and then back south as the rainfall patterns change.
Composition of Atmospheric Gases
The distribution of some species changes in areas where there is more air pollution.
Some species of lichen can't be grown in areas where sulfur dioxide is given out by industrial processes.
Caused by seasonal factors, geographic factors or human interaction,
The Water Cycle
The water on planet Earth is constantly recycled.
Energy from the Sun makes water evaporate from the land and sea, turning it into water vapour. Water also evaporates from plants (this is called transpiration).
The warm water vapour is carried upwards as warm air rises, and when it gets higher up, it cools and condenses to form clouds.
Water falls from the clouds as precipitation onto the land which provides fresh water for plants and animals.
The water is then drained into the sea, before the whole process starts again.
The Carbon Cycle
Carbon enters the atmosphere as carbon dioixde from respiration and combustion.
Carbon dioxide is aborbed by producers to make carbohydrates for photosynthesis.
Animals feed on the plant passing the carbon compounds along the food chain. Most of the carbon they consume is exhaled as carbon dioxide formed during respiration. The animals and plants eventually die.
The dead organisms are eaten by decomposers and the carbon in their bodies is returned to the atmosphere as carbon dioxide. In some conditions decomposition is blocked. The plant and animal material may then be available as fossil fuel in the future for combustion.
Compost is decomposed organic matter that is used as a natural fertiliser for crops and garden plants.
Farmers and gardeners try to provide the ideal conditions for quick decay to make compost.
Factors affecting the Rate of Decay
Wamrer temperatures - things decompose quicker as they increase the rate that the enzymes involved in the decomposition work at.
Too hot - decomposition slows down or stops as the enzymes are destroyed and the organisms die. Cold temperatures - slower rate of decomposition.
Decay takes place faster in moist environments because the organisms involved in decay need water to carry out biological processes.
Many organisms need oxygen to respire, which they need to do to survive.
The microorganisms involved in anaerobic decay don't need oxygen.
Number of Decay Organisms
The more microorganisms and detritus feeders there are, the faster decomposition happens.
Biogas is made by anaerobic decay of waste material
Biogas is mainly made up of methane, which can be burned as a fuel.
Lots of different microorganisms are used to produce biogas.
They decay plant and animal waste anaerobically. This type of decay produces methane gas.
Biogas is made in a simple fermenter called a digester or generator.
Biogas generators need to be kept at a constant temperature to keep the microorganisms respiring.
Not all Biogas Generators are the same
generators - make biogas in small batches, manually loaded up with waste which is left to digest, and the by-products are cleared away at the end of each session.
generators - make biogas all the time, waste is continuously fed in and biogas is produced at a steady rate. Continuous generators are more suited to large-scale biogas projects.
Biodiversity and Waste Management
Biodiversity is the variety of different species of organisms on Earth, or within an ecosystem.
High biodiversity makes sure that ecosystems are stable because different speices depend on each other. Different species can maintain the right physical environment for each other.
Lots of human action, including waste production and deforestation, as well as global warming are reducing biodiversity.
Increasing Environment Demands
Our increasing population puts pressure on the environment.
We use raw materials such as oil, but we also use more energy for the manufacturing processes. This means we're taking more and more resources from the environment more and more quickly.
We're producing more waste
Sewage and toxic chemicals from industry can pollute lakes, rivers and oceans, affecting the plants and animals that rely on them for survival.
And the chemicals used on land can be washed into water.
We use toxic chemicals for farming.
We also bury nuclear waste underground, and we dump a lot of household waste in landfill sites.
Smoke and acidic gases released into the atmosphere can pollute the air, e.g. sulfur dioxide can cause acid rain.
CO2 and Methane trap energy from the Sun
The temperature of the Earth is a balance between the energy it gets from the Sun and the energy it radiates back out into space.
Gases in the atmosphere naturally act like an insulating layer. They absorb most of the energy that would normally be radiated back out into space. This increase the planet's temperature.
If this didn't happen, then at night there'd be nothing to keep any energy in, and we'd quickly get very cold.
There are several different gases in the atmosphere which help keep the energy in. They're called greenhouse gases.
The Earth is gradually heating up because of the increasing levels of greenhouse gases - this is global warming.
Consequences of Global Warming
Sea levels rising
Higher temperatures = seawater expansion and ice melting = rise in sea level
Sea level has risen a little over past 100 years.
If sea level keeps rising it's bad for people and animals living in low-lying places.
It will lead to flooding, resulting in the loss of habitats.
Changes in species distribution
The distribution of many wild animal and plant species may change as temperatures increase and the amount of rainfall changes.
Some species may become more widely distributed.
Other species may become less widely distributed.
Changes in migration patterns
There could be changes in migration patterns.
For example, some birds may migrate further north, as more northern areas are getting warmer.
Reduction in biodiversity
Biodiversity could be reduced if some species are unable to survive a change in the climate, so become extinct.
Deforestation and Land Use
Purposes of land for humans
We use land for things like building, quarrying, farming and dumping waste.
This means that there's less land available for other organisms.
Sometimes, the way we use land has a bad effect on the environment - for example, if it requires deforestation or the destruction of habitats like peat bogs and other areas of peat/
Destroying peat bogs
Bogs are areas of land that are acidic and waterlogged. Plants that live in bogs don't fully decay when they die as there's not enough oxygen.
So the carbon of the plants is stored in the peat instead of being released into the atmosphere.
However, peat bogs are often drained so that the area can be used as farmland, or the peat is cut up and dried to use as fuel. It's sold to gardeners as compost.
When peat is drained, it comes into more contact with air and some microorganisms start to decompose it.
When these microorganisms respire, they use oxygen and release carbon dioxide, contributing to global warming. CO2 is also released when peat is burned as a fuel.
Destroying the bogs also destroys the habitats of some of the animals, plants and microorganisms that live there, so reduces biodiversity.
Deforestation is the cutting down of forests.
This causes big problems when it's done on a large-scale, such as cutting down rainforests in tropical areas.
Deforestation happens for many reasons, two of them are...
To clear land for farming to provide food.
To grow crops from which biofuels based on ethanol can be produced.
Less carbon dioxide taken in - amount of CO2 removed from the atmosphere during photosynthesis is reduced.
More carbon dioxide in the atmosphere - CO2 is released when trees are burnt to clear land. Microorganisms feed on bits of dead wood which releases CO2 as a waste product of respiration.
Less biodiversity - the more species, the greater the biodiversity. When habitats like forests are destroyed, there is a danger of many species becoming extinct, thus reducing biodiversity.
Maintaining Ecosystems and Biodiversity
It's important that biodiversity is maintained at a high enough level to make sure that ecosystems are stable.
In some areas, programmes have been set up by concerned citizens and scientists to minimise damage by human activities to ecosystems and biodiversity.
1. Breeding Programmes
Set up to help prevent endangered species from becoming extinct.
Animals are bred in captivity to make sure the species survives if it dies out in the wild.
Individuals can sometimes be released into the wild to boost or re-establish a population.
2. Habitat Protection
Protects and regenerates rare habitats like magroves, heathland and coral reefs.
Protecting these protects the species that live there thus preserving the ecosystem and biodiversity.
3. Preventing Global Warming
Some governments have introduced regulations and programmes to reduce the level of deforestation taking place and the amount of CO2 being released into the atmosphere by businesses.
This could reduce the increase of global warming.
4. Reducing Waste
People are encouraged to recycle to reduce the amount of waste that gets dumped in landfill sites.
This could reduce the amount of land taken over landfill, leaving ecosystems in place.
The Costs of Programmes
Protecting biodiversity costs money.
For example, governments sometimes pay farmers to subsidy to reintroduced hedgrows and field margins to their land.
It can cost money to keep a watch on whether the programmes and regulations designed to maintain biodiversity are being followed.
There can be conflict between protecting biodiversity and saving money - money can be prioritised for other things.
The effect on the local economy
Protecting biodiversity may come at a cost to local people's livelihoods.
For example, reducing the amount of deforestation is great for biodiversity, but the people who were previously employed in the tree-felling industry could be left unemployed.
This could affect the local economy if people move away with their family to find work.
Protecting Food Security
There can be conflict between protecting biodiversity and protecting our food security.
Sometimes certain organisms are seen as pests by farmers and are killed to protect crops and livestock so that more food can be produced.
As a result, however, the food chain and biodiversity can be affected.
The Development of Society
Development can affect the environment.
Many people want to protect biodiversity in the face of development, but sometimes land is in such high demand that previously untouched land with high biodiversity has to be used for development.
For example, for housing developments on the edges of towns, or for new agricultural land in developing countries.
Trophic levels are different stages of a food chain. They consist of one or more organisms that perform a specific role in the food chain.
Trophic levels are named after their location in the food chain using unmbers. First level is trophic level 1 and each level after that is numbered in order based on how far along the food chain the organisms in the trophic level are.
Different organisms are adapted to different abiotic conditions.