Ecology

• Habitat - the place where an organism lives.
• Population - all the organisms of one species living in a habtat.
• Community - the populations of different species living in a habitat.
• Abiotic factors - non-living factors of he enviroment, e.g. temperature.
• Biotic factors - living factors of the enviroment, e.g. food.
• Ecosystem - the interactionnof a community of living orgainism with the non-living parts of the enviroment.

Plants compete for light, space, water and mineral ions from the soil. Whilst animals need territory, food, water and mates.

Independence is when, whithin a community, each species depends on other species for food, shelter, pollination and speed dispersal.

In some communities all the species and enviromental factors are in balance so that the population sizes are roughly constant, this is called a stable community

Abiotic factors are non-living, for example: moisture, light intensity, temperature, carbon dioxide level, wind intenisity and direction,oxygen level, and soil pH and mineral content.

A change in these can affect the size of the population. For example, a decrease in light intensity, temperature or level of carbon dioxide could decrease the rate of photosynthesis, affecting plant growth and decreasing the population size.

Biotic factors are living-factors, for example: new predators arriving, competition, new pathogens, availability of food.

A change in these can also affact populatin size, for example a new predator could cause a decrease in prey population

Organisms,including microogrganisms, are adapted to live in different conditions. Adaptations can be stuctural ( feactures of an organism's body structure, such as shape or colour ) behavioural ( ways that the organisms behave, for example micration ) and functinal ( things insid ethe organism's body that can be related to processes such as reproduction and metabolism, for example, hibernation)

Some microogansms, such as bacteria, are known extremophiles and are adapted to live in extreme conditions such as high temperatures, high salt concentations, or high pressure.

• Food chains always start with a producer which makes its own foor using energy from the sun, for example green plants or algae.
• When a green plant produces glucose, ome of it is used to make othe biological molecules in the plant, this is called the plant's biomass (the mass of  a living material).
• Energy is transfred through the ecosystem when organisms get eaten.
• Producer > Primary consumer > Secondary consumer

In a stable community:

• The population of a species is limited by the food available.
• If the population of the prey increases, so will the population of the predators.
• As the population of the predators increase, the number of prey will decrease, resulting in a predator-prey cycle.
• Predator-prey cycles are always out of phase with eath other as it takes a while for one population to respond to changes in the population, for example it takes time for organisms to reproduce.

The distribution of an organism is where an organism is found, this is affected by enviromental factors, for example there will likely be more flowers in the open rather than under a tree.

A quadrat is a square frame enclosing a known area , used to compare how common an organism is in to sample area:

• Place a 1m^2 quadrat on the ground at a random point within the first sample area.
• Count all the organisms within the quadrat.
• Repeat steps 1 and 2 as many times as you can.
• Work ou the mean number of organisms per quadrat within the first sample area.
• Repeat step 1-4 in a second sample area.
• Compare the two means.

The population size of an organism is also called its abundance. You can work this out by finding the mean number of organisms per m^2 and then multiplying it by the total area of the habitat.

You can use lines called transects to help find out how organisms are distributed across an area:

• Mark out a line in the area you want to study using a tape measure.
• Collect data along the line by counting all the organisms you're interesting in that touch the line or collect the data using quadrats placed next to each other along the line or at intervals.

If its difficult to count all the organisms, you can calculate the percentage cover by estimating the percentage area of the quadrat covered by a particula type of organism:

• Count the number of squaes covered by organism A.
• Make this into a percentage - divide the number of squares covered by the organism by the total number of squares in the quadrat then multiply the result by 100.
• Do the same for organism B.

• 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 up, cools down, condeses and forms clouds.
• Water fall from the clouds a precipitation (usually rain) onto land to provide fresh water.
• Some is absorbed by the soil and taken up by plants for photosythesis. Some of this becomes part of the plants' tissue and is passed along to animals in the food chain.
• Some is drunk by animal, needed for the chemical reactions that happen in their bodies. Animals return water to the soil and atmosphere through excretion (sweating, urination, breathing, ect.).
• Water that doesnt get absorbed by the soil will runoff into streams and rivers.
• From here, the water then drain back into the sea, before it evaporates all over again.

Living things are made up of material from the enviroment aroud them. For examle, plants turn elements like carbo, oxygen, hydrogen and nitrogen from the soil and the air into the complex compounds (carbohydrates, proteins, and fats) that make up living organisms, these get passed up the food chain.

These materials are returned to the enviroment as waste product when organisms die and dacay. Decay happens when microorganisms brake downmaterials. This happens faster in warm, moist, aerobic conditionsnas the microorganisms are more active. These waste products provide what plants need to grow.

In a stable community, the materials that are taken out of the soil and used are balanced by those put back in

• CO2 is removd from the atmosphere by green plants during photosythesis and carbon is used to make glucose, necessary for carbohydrates, fats and protein which make up plants and algae.
• As the plants and algae respire, some carbon is returned to the atmosphere.
• When plants are eaten some carbon becomes part of the protein and fat and gets passed up the food chain.
• When the animals respire, some carbon is returned to the atmosphere.
• When organiss die (or produce waste) detritus feeders and microoganisms feed on their remains. When these respire, caron is returned to the atmosphere.
• The combustion of wood and fossil fuels also releases carbon back into the atmosphere.

Biodiversity is the variety of different species of organims on earth,or within an ecosytem.

High biodiversity is important to make sure ecosystems are stable. However, lots of human actions, like waste production, deforestation and global warming are reducing biodiversity.

Humans are having a greater affect then ever before on the enviroment as the population is so big. This is mostly due to modern medicine and farming methods which prevent people from dying. The increase in population size means that our actions can have widespread effects. People are demanding a higher standard of living, so more raw mateials and energy is being used. This means that many raw materials are being used up quicker than theyre replaced.

As more things are made, more waste, including chemical waste, is created. Unless handled properly, this waste can turn into harmful pollution, affecting the water, land and air, and killing animals.

• Water - sewage and toxic chemicals from industry can polute wate, affecting who drink it. Chemicals used on land can also be washed into water.
• Land - Toxic chemicals used for farming, nuclear waste buried underground and landfills all pollute the land.
• Air - Smoke and acidic gases released into the atmosphere can pollute the air, for example sulphuric acid causes acid rain.
  

The temperature of te earth is a balance between energy from the sun and energy radiated back out into space.

Gasses in the atmosphere natually act like an insulating layer, absorbing energy that would be radiated into space and re-radiate it in all direction, thus increasing the earth's temperature.

Greenhouse gasses, particually carbon dioxide and methane, help keep the energy in, however the levels are rising quickly and becoming out of control.

The Earth is heating up due to and increase of greenhouse gasses: global warming. This can also affect other types of climate change:

• changing rainfall patterns.
• rising sea levels due to expanding sea water and ice melting, causing flooding.

This may change animal's migration patterns, the distributin of animals to change, and biodiversity could be reduced due to extinction

Humans use land for things like building, quarrying, faring and dumping waste, meaning there is less available for other organisms. Our use sometimes results in deforestation or the destruction of habitats like peat bogs and other aeas of peat.

Deforestation is used to clear land for farming to provide more food and to grow crops, however this has three main negative effects:

• Less carbon dioxide taken in - Amount of carbon dioxide removed during potosythesis is reduced and less carbon dioxide is "locked up" in the wood of trees.
• More carbon dioxide in the atmosphere - Carbon dioxide released when trees are burnt to clear land. Microoganisms feeding on bits of dead wood also release carbon through respiration.
• Less biodiversity - There is a danger of many species becoming extinct.

Bogs are areas of land that are acdidc and waterlogged. Plants living here do not fully decay due to insufficient oxygen. These build up to form peat, which store carbon. Peat bogs are sometimes drained so the land can be used for farming, dried to be used as fuel, or sold as compost. When peat is drained it comes into contact with air and microorganisms start to decompose it, releasing carbon dioxide when they respire. Carbon dioxide is also released when its burn for fuel and destroying bogs destroys the habitat for many organisms, reducing biodiversity

It is important to maintainn a high level of biodiversity to ensure the ecosystems are stable, therfore some programmes have been set up to help this:

• Breeding programmes to prevent endangered species becoming extinct.
• Programmes to protect and regenerate rare habitats and preserve the ecosytems there.
• Programmes reintroducing hedgegrows and field margins around single-crop fields. to allow wild flowers and grasses to grow, providing a habitat for a wider variety of organisms.
• Regulations and programmes set by the government to reduce the level of deforestation and the amount of carbon dioxid being realeased by businesses.
• People are encouraged to recycle to reduce the amount of waste that gets dumped in landfills.

however...

• It costs alot of money.
• May cost to local people's livelihood, which could also effect the local economy.
• Conflict between protecting biodiversity or food security (pests being killed to protect crops).
• The world is growing and developing, and sometimes land is needed.