Ecosystem and Material Cycles

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Ecosystem and Material Cycles- Investigating ecosystem

Quadrats

Some ecosystems are very complex with large numbers of different species of different population sizes

sampling is often used to estimate the distribution and abundance of species (different samples of the area can be taken and used to make an estimate for the total species numbers in the area)

When carrying out sampling, square frames called quadrats can be used to mark off the area being sampled

Quadrats are square frames made of wood or wire

They can be a variety of sizes eg. 0.25m2 or 1m2

They are placed on the ground and the organisms within them are recorded

Plants species are commonly studied using quadrats to estimate their abundance

To estimate population size you work out the mean number of organisms per m^2. Then multiply mean by total area of the habitat.

Practical

You can use a quadrat to help find out how organisms are distributed along a gradient.

The quadrats are laid out along a line forming a belt transect

Mark a line in area you study

Collect data along line using quadrats placed next to each other, collect data by counting all the organisms of the species you're interested in

Record other data such as mean height and abiotic factors

Repeat steps 2 and 3 several times then find mean number of organisms

Plot graph to see if the changing in abiotic factors is correlated with a change in the distribution of the species you are studying

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Ecosystem and Material Cycles- Human impacts on biodiversity

Human interactions within the ecosystem may have a positive impact on biodiversity such as conservation or a negative affect such as eutrophication. Negative effects include reduced populations, reduced biodiversity or extinction.

Overuse of fertilisers can cause eutrophication and reduce biodiversity

As the human population increases, we need more food and increased use of fertilisers has impacted on the biodiversity of aquatic environments through eutrophication.

Nitrates in the fertilisers run off from fields into rivers and lakes causing the overgrowth of algae.

The light is blocked so plants cannot photosynthesise so they die. T

his causes bacteria to decompose the plants and use up most of the oxygen in the water. Without oxygen, animals such as fish will die.

This is a negative impact as the biodiversity of the river or lake will decrease.

Fish farming can reduce biodiversity

Fish are farmed in large nets or tanks within lakes or in the sea.

Farm waste, chemicals, pathogens and parasites are released into the surrounding water, harming other marine life.

Carnivorous species of farmed fish, such as salmon, need high amounts of protein in their diet. They are often fed on wild fish, reducing their populations.

Sometimes fish can escape and compete with indigenous wild species and compete for resources, resulting in reduced biodiversity. Predators of the fish such as sea lions can become trapped in the nets and die.

Introduction of non-indigenous species can reduce biodiversity

A non-indigenous species does not live in an area and may be introduced by humans for a particular purpose such as removal of pest species or for hunting. However, the new species may out-compete or kill indigenous or naturally occurring species.

These may be reduced in number, resulting in reduced biodiversity or maybe extinction.

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Ecosystem and Material Cycles- Conservation and biodiversity

Reforestation

When land from a forest previously stood is replanted to form a new forest

Forest have high biodiversity as they contain wide variety of trees and plants. They provide food and shelter for different animal species. Deforestation reduces biodiversity by removing trees. Reforestation helps to restore trees

Reforestation programmes have to be carefully planned to maximise positive effect

Conservation schemes

Helps to protect biodiversity by preventing species from dying out

Conservation methods are;

Protecting a species natural habitat

Protecting a species in a safe zone away from danger

Seed banks to store and distribute seeds of rare plants

Maintaining biodiversity benefits

Protecting human food supply- Over fishing reduced fish stocks. Conservation plans ensure that future generations will have fish to eat

Minimal damage to food chain- ne species becomes extinct affect the whole food chain, so conserving one species help others to survive

Future medicines- Medicines come from plants. Undiscovered plant species may contain new medical chemicals. Plants become extinct valuable medicines could go to waste.

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Ecosystem and Material Cycles- Carbon cycle

The carbon cycle shows how atoms of this element can exist within different compounds at different times.

All cells - whether animal, plant or bacteria - contain carbon, because they all contain proteins, fats and carbohydrates. Plant cell walls, for example, are made of cellulose - a carbohydrate.

Carbon is passed from the atmosphere, as carbon dioxide, to living things, passed from one organism to the next in complex molecules, and returned to the atmosphere as carbon dioxide again. This is known as the carbon cycle.

Removing carbon dioxide from the atmosphere

Green plants remove carbon dioxide from the atmosphere by photosynthesis. The carbon becomes part of complex molecules such as proteins, fats and carbohydrates in the plants.

Returning carbon dioxide to the atmosphere

Organisms return carbon dioxide to the atmosphere by respiration. It is not just animals that respire. Plants and microorganisms do, too. Carbon dioxide is also released by combustion. The burning of fossil fuels releases large quantities into the atmosphere.

Passing carbon from one organism to the next

When an animal eats a plant, carbon from the plant becomes part of the fats and proteins in the animal. Decomposers and some animals, called detrivores, feed on waste material from animals, and the remains of dead animals and plants. The carbon then becomes part of these organisms.

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Ecosystem and Material Cycles- Water cycle

Water is a key compound for life on Earth. All living organisms need water. Some can survive in a dormant state without it for long periods of time, but all organisms will eventually die without it.

Water is constantly recycled. Energy from the Sun evaporates water from the land and sea forming water vapour. This rises up into clouds and then cools, condenses and falls as rain onto the ground. The water then drains into the sea and the water cycle starts again.

Desalination

Desalination is a process that takes away mineral components from saline water. More generally, desalination refers to the removal of salts and minerals from a target substance, as in soil desalination, which is an issue for agriculture. Saltwater (especially sea water) is desalinated to produce water suitable for human consumption or irrigation.

Drought

Droughts often mean a shortage of water.

Reverse Osmosis

Reverse osmosis is a means of pulling clean water out of polluted water or saltwater by pushing water through a membrane under pressure. An example of reverse osmosis is the process by which contaminated water is filtered under pressure.

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Ecosystem and Material Cycles- Nitrogen cycle

Nitrogen is essential for the formation of amino acids which form proteins. The nitrogen cycle is a model that explains how nitrogen is recycled.

There's lot of nitrogen in the air - about 78 per cent of the air is nitrogen. Because nitrogen is so unreactive, it cannot be used directly by plants to make protein. Only nitrates are useful to plants, so we are dependent on other processes to convert nitrogen to nitrates in the soil.

Nitrogen gas from the air is converted to nitrate compounds by nitrogen-fixing bacteria in soil or root nodules. Lightning also converts nitrogen gas to nitrate compounds. The Haber process is a man-made process where nitrogen gas is converted into ammonia which is used to make fertilisers. Farmers use fertilisers like ammonium nitrate to help crops to grow and increase yields.

Ammonia is converted to nitrates by nitrifying bacteria in the soil.

Plants absorb nitrates from the soil and use these to build up proteins. The plant may be eaten by an animal, and its biomass used to produce animal protein.

Decomposers break down the bodies of dead organisms, urine and faeces resulting in nitrogen being returned to the soil as ammonia. This ammonia is converted to nitrates by nitrifying bacteria.

In some conditions denitrifying bacteria in the soil break down nitrates and return nitrogen back to the air. This is usually in waterlogged soil. Improving drainage reduces this effect, making the soil more fertile by retaining more nitrates.

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Ecosystem and Material Cycles- Nitrogen cycle

Crop rotation and improved soil fertility

Farmers often grow crops such as peas, beans or clover as these crops can form nitrate, as they have nitrogen-fixing bacteria in their roots. This will increase the nitrate content and fertility of the soil. Crop plants will take in the nitrate and use it to make proteins for growth. One year the farmer will grow one of these crops and then the following years, the farmer will plant another crop in the nitrate rich soil. Growing different crops each year in a cycle is called crop rotation.

Using fertilisers

Natural fertilisers such as manure or compost are used by farmers to provide a source of nitrate to increase crop yield. Expensive artificial fertilisers such as ammonium nitrate can be applied to the fields.

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Ecosystem and Material Cycles- Questions from spec

Q. Explain the benefits of maintaining local and global biodiversity, including the conservation of animal species and the impact of reforestation

A.

The interactions between organisms in an ecosystem mean that organisms, populations or whole species may depend on one another Due to this interdependence, maintaining biodiversity is key in maintaining the stability of the ecosystem and avoiding disruption which could lead to the loss of species

The increase in the human population and waste it produces, deforestation, peat bog destruction and global warming are all reducing biodiversity. Conservation helps reverse this. Conservation is the preservation of ecosystems and the organisms that live within them.

Q. Describe how different materials cycle through the abiotic and biotic components of an ecosystem

A. Biotic factors are the living things in an ecosystem so they do not recycle. Abiotic factors are the different physical and chemical components available like temperature, air, water, minerals, rocks, and PH.

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Ecosystem and Material Cycles- Questions from spec

Q. Explain the importance of the carbon cycle, including the processes involved and the role of microorganisms as decomposers

A.

The carbon cycle shows how atoms of this element can exist within different compounds at different times.

All cells - whether animal, plant or bacteria - contain carbon, because they all contain proteins, fats and carbohydrates. Plant cell walls, for example, are made of cellulose - a carbohydrate.

Carbon is passed from the atmosphere, as carbon dioxide, to living things, passed from one organism to the next in complex molecules, and returned to the atmosphere as carbon dioxide again. This is known as the carbon cycle.

Removing carbon dioxide from the atmosphere

Green plants remove carbon dioxide from the atmosphere by photosynthesis. The carbon becomes part of complex molecules such as proteins, fats and carbohydrates in the plants.

Returning carbon dioxide to the atmosphere

Organisms return carbon dioxide to the atmosphere by respiration. It is not just animals that respire. Plants and microorganisms do, too. Carbon dioxide is also released by combustion. The burning of fossil fuels releases large quantities into the atmosphere.

Passing carbon from one organism to the next

When an animal eats a plant, carbon from the plant becomes part of the fats and proteins in the animal. Decomposers and some animals, called detrivores, feed on waste material from animals, and the remains of dead animals and plants. The carbon then becomes part of these organisms.

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Ecosystem and Material Cycles- Questions from spec

Q. Explain the importance of the water cycle, including the processes involved and the production of potable water in areas of drought including desalination

A.

Water is a key compound for life on Earth. All living organisms need water. Some can survive in a dormant state without it for long periods of time, but all organisms will eventually die without it.

Water is constantly recycled. Energy from the Sun evaporates water from the land and sea forming water vapour. This rises up into clouds and then cools, condenses and falls as rain onto the ground. The water then drains into the sea and the water cycle starts again.

Desalination

Desalination is a process that takes away mineral components from saline water. More generally, desalination refers to the removal of salts and minerals from a target substance, as in soil desalination, which is an issue for agriculture. Saltwater (especially sea water) is desalinated to produce water suitable for human consumption or irrigation.

Drought

Droughts often mean a shortage of water.

Reverse Osmosis

Reverse osmosis is a means of pulling clean water out of polluted water or saltwater by pushing water through a membrane under pressure. An example of reverse osmosis is the process by which contaminated water is filtered under pressure.

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Ecosystem and Material Cycles- Questions from spec

Q. Explain how nitrates are made available for plant uptake, including the use of fertilisers, crop rotation and the role of bacteria in the nitrogen cycle

A.

Nitrogen is essential for the formation of amino acids which form proteins. The nitrogen cycle is a model that explains how nitrogen is recycled.

There's lot of nitrogen in the air - about 78 per cent of the air is nitrogen. Because nitrogen is so unreactive, it cannot be used directly by plants to make protein. Only nitrates are useful to plants, so we are dependent on other processes to convert nitrogen to nitrates in the soil.

Nitrogen gas from the air is converted to nitrate compounds by nitrogen-fixing bacteria in soil or root nodules. Lightning also converts nitrogen gas to nitrate compounds. The Haber process is a man-made process where nitrogen gas is converted into ammonia which is used to make fertilisers. Farmers use fertilisers like ammonium nitrate to help crops to grow and increase yields.

Ammonia is converted to nitrates by nitrifying bacteria in the soil.

Plants absorb nitrates from the soil and use these to build up proteins. The plant may be eaten by an animal, and its biomass used to produce animal protein.

Decomposers break down the bodies of dead organisms, urine and faeces resulting in nitrogen being returned to the soil as ammonia. This ammonia is converted to nitrates by nitrifying bacteria.

In some conditions denitrifying bacteria in the soil break down nitrates and return nitrogen back to the air. This is usually in waterlogged soil. Improving drainage reduces this effect, making the soil more fertile by retaining more nitrates.

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Ecosystem and Material Cycles- Questions from spec

Q. Explain how nitrates are made available for plant uptake, including the use of fertilisers, crop rotation and the role of bacteria in the nitrogen cycle

A.

Crop rotation and improved soil fertility

Farmers often grow crops such as peas, beans or clover as these crops can form nitrate, as they have nitrogen-fixing bacteria in their roots. This will increase the nitrate content and fertility of the soil. Crop plants will take in the nitrate and use it to make proteins for growth. One year the farmer will grow one of these crops and then the following years, the farmer will plant another crop in the nitrate rich soil. Growing different crops each year in a cycle is called crop rotation.

Using fertilisers

Natural fertilisers such as manure or compost are used by farmers to provide a source of nitrate to increase crop yield. Expensive artificial fertilisers such as ammonium nitrate can be applied to the fields.