OCR B GCSE Geography - Sustaining Ecosystems

What is an Ecosystem?

A community of plants and animals which live together and interact in an environment. Made up of biotic and abiotic factors

What is a Biotic Factor?

A living factor

What is an Abiotic Factor?

A non-living factor

What are Biomes?

Ecosystems on a global scale, such as tropical rainforests or deciduous woodland. These global ecosystems are called biomes.

What is a Producer?

An organism that uses sunlight energy to produce food.

What is a Consumer?

An organism that obtains its energy by eating other organisms - it eats producers or other consumers.

What is the difference between Food Chains and Food Webs?

A food chain shows the different elements that live in an ecosystem, and what eats what to survive. A food web is more complex and shows all the different elements in a habitat and how they overlap.

What is a Decomposer?

An organism that gets its energy by breaking down dead material. e.g. dead consumers or fallen leaves. Examples of decomposers include Bacteria and Fungi.

What is a Dependent Ecosystem?

Some parts of an ecosystem depend on others, e.g. consumers depend on producers for a source of food and some depend on them for a habitat. If one part changes, it affects all the other parts that depend on it.

Where are Tropical Rainforests typically found?

Tropical rainforests are found close to the Equator within the Tropics of Cancer and Capricorn (23.5° north and south of the Equator).

Where are Hot Deserts found?

Hot desert ecosystems are found between 5° and 30° north and south of the Equator near the Tropics of Cancer and Capricorn.

Where are Tropical Grasslands found?

Tropical grasslands (savannah) are located between the latitudes of 5° and 30° north and south of the Equator, within central parts of continents.

Where are Temperate Grasslands found?

Temperate grasslands lie in the centre of continents, between the latitudes of around 40° - 60° north of the Equator .

Where are Deciduous Forests found?

Deciduous forests are in temperate latitudes; they are located further north. They form the natural vegetation cover not only for the UK, but also over much of western and central Europe.

Where are Polar Regions found?

Polar regions are found towards the north and south pole above the Arctic and Antarctic circles (66° north and south).

Where are Coral Reefs found?

Coral reefs are found within 30 north and south of the Equator in tropical and sub-tropical oceans close to the coast.

What is the Climate of Hot Deserts?

The climate in the hot desert is characterised by high temperatures. Daytime temperatures can get up to over 40C but at night it can get very cold (below freezing) because there's no cloud to keep in the heat. There is a large daily temperature range. The hot desert is also very dry with less than 250mm of rainfall per year. There are two seasons - summer, when the sun is high in the sky and it's very hot, and winter when it is slightly cooler (although still very warm compared to the UK).

What are the Flora of Hot Deserts?

The vegetation has adapted to survive in the harsh desert climate. Some plants store water in their roots, stems, leaves or fruits (these are known as succulents). Some plants have horizontal root systems, just below the surface, to soak up water when it rains. Some plants have long taproots (7-10m deep) to reach groundwater. Most plants have small leaves or spines and glossy/waxy leaves to reduce moisture loss. Seeds often stay dormant for years but can germinate quickly when it rains.

What are the Fauna of Hot Deserts?

Meerkats have adapted to limited food supply in the desert by feeding on scorpions whose venom they are immune to. Camels have humps on their back to store fat and water. They also have long eyelashes for keeping out sand and wide feet to help them walk on the sand.

What is the Climate of Tropical Rainforests?

The daily temperature is about 28C. It never goes below 20C and rarely above 35C. It is a very wet climate, at least 2000mm of rain falls a year. This makes the atmosphere very hot and humid. There are no real seasons. Each day's weather is the same - starting off hot and dry, with thunderstorms and heavy rain in early evening.

What are the Flora of Tropical Rainforests?

The vegetation in rainforests grows in distinct layers and has adapted to the climate and poor soils. Trees are very tall, and trunks are thin to reach sunlight. Buttress roots support these tall trees in shallow soils. Lianas are woody vines that climb high to reach the sunlight. Leaves in the tropical rainforest have drip tips to allow rainfall to drip down to the lower layers and shed heavy rainfall easily.

What are the Fauna of Tropical Rainforests?

Most of the birds, animals and insects live in the canopy layer. Many animals are camouflaged e.g. leaf-tailed geckos look like leaves so they can hide from predators. Some animals are nocturnal e.g. sloths, they sleep during the day and feed during the night when it's cooler. This helps them to save energy.

What is the Climate of Tropical Grasslands?

They have quite low rainfall (800-900mm per year) and distinct wet/dry seasons. Temperatures peak at around 35c just before the wet season and lowest (around 15c) just after it. The wet rainy seasons occurs when the Sun moves overhead bringing with it the ITCZ (a belt of low pressure which brings bursts of heavy rainfall).

What are the Flora of Tropical Grasslands?

In the summer wet season grasses such as pampas grow very quickly to over 3m. The baobab tree has adapted to the climate by growing large swollen stems and a trunk with a diameter of 10m. The root-like branches hold only a small amount of leaves to reduce moisture loss. The bark of the baobab tree is thick to retain moisture and roots are long to tap into supplies of water deep within the ground. Many trees are also drought-resistant (xerophytic) or fire-resistant (pyrophytic)

What are the Fauna of Tropical Grasslands?

The savannah grasslands contain the world's greatest diversity of hoofed animals. There are herbivores such as antelopes. Carnivores in this ecosystem (e.g. lions) stalk herds of animals.

What is the Climate of Temperate Grasslands?

Hot summers (up to 40c) and cold winters (down to -40c). They have low rainfall (250-500mm) mainly in late spring/early summer.

What are the Fauna of Temperate Grasslands?

Grazing animals such as antelopes travel long distances in search of food and water. There are burrowing animals such as gophers and rabbits.

What are the Flora of Temperate Grasslands?

Vegetation doesn't grow as quickly or as tall as in the savannah. Trees and shrubs struggle to grow but some trees such as oak and willow grow along river valleys where more water is available. Tussock grasses are found in clumps and grow to 2m tall. Buffalo and feather grass grow more evenly across the land, up to around 50cm in height. Flowers including sunflowers and wild indigos can grow among the grasses.

What is the Climate of Temperate Deciduous Forests?

They are mainly found in Western Europe (including the UK) and the eastern parts of North America and Asia. The summers in these areas are warm and the winters cool. The annual temperature range in these areas is low, precipitation can occur throughout the year and there is a long growing season.

What are the Flora of Temperate Deciduous Forests?

Deciduous trees lose their leaves in the winter, when the light level and temperature falls. The vegetation in temperate deciduous forests grows in layers. The ground layer is dark and damp - ideal for plants like moss. Plants in the herb layer flower early, before the larger plants grow leaves and block out the light. The sub-canopy layer grows in the spaces between the taller trees, where there's more water when it rains and more light. Some roots are longer to reach different layers in the soil and reach moisture.

What are the Fauna of Temperate Deciduous Forests?

Temperate forests have fewer animal species than tropical grasslands. Animals must adapt to warm summers and cold winters. Some animals migrate to warmer places in winter and some hibernate. Black bears are found in the temperate forests of North America. They have a heavy coat made of many layers of fur and build up a 5-inch layer of fat before hibernating for the winter. They also have long claws to climb trees and are omnivores (can eat plants and animals).

What is the Climate of Polar Environments?

Very cold, temperatures are usually below 10c. Winters are normally below -40c and can reach almost -90c. Rainfall (and snowfall) is low, no more than 500mm per year. Clearly defined seasons with cold summers and even colder winters.

What are the Flora of Polar Environments?

Very few plants. Some lichens and mosses are found on rocks. On the coast in summer there are some grasses and flowering plants. Plants grow very slowly and are not tall. At the poles only mosses and lichens can survive. Some small, short trees and shrubs can grow in warmer, sheltered areas.

What are the Fauna of Polar Environments?

Very few species of animals. Polar bears (Arctic) and penguins (Antarctic) and marine mammals such as whales, seals and walruses.

What is the Climate of Coral Reefs?

Found in warm areas with a mean temperature of at least 18c. They grow best in shallow, clear, salty water.

What are the Flora of Coral Reefs?

As they are underwatering few plants grow on coral reefs. Tiny algae live inside the tissue of corals. The algae and coral depend on each other for nutrients. Sea grasses such as turtle grass and manatee grass are commonly found in the Caribbean Sea.

What are the Fauna of Coral Reefs?

Coral itself is an animal. Around 25% of all marine species live in coral reefs. Parrot fish feed directly on the polyps, tearing the coral to get to them. Clams settle on the coral bed and filter plankton from seawater. Many fish have flat bodies so they can easily swim.

What is the Water Cycle of the Tropical Rainforest?

The roots of plants take up water from the ground and the rain is intercepted as it falls - much of it at the canopy level. As the rainforest heats up, the water evaporates into the atmosphere and forms clouds to make the next day's rain. This is convectional rainfall.

What is the Nutrient Cycle of the Tropical Rainforest?

The rainforest nutrient cycling is rapid. The hot, damp conditions on the forest floor allow for the rapid decomposition of dead plant material. This provides plentiful nutrients that are easily absorbed by plant roots. However, as these nutrients are in high demand from the rainforest's many fast-growing plants, they do not remain in the soil for long and stay close to the surface of the soil. If vegetation is removed, the soils quickly become infertile and vulnerable to erosion.

What is the typical Climate of Tropical Rainforests?

The daily temperature is about 28C. It never goes below 20C and rarely above 35C. It is a very wet climate, at least 2000mm of rain falls a year. This makes the atmosphere very hot and humid. There are no real seasons. Each day's weather is the same - starting off hot and dry, with thunderstorms and heavy rain in early evening.

What are Rainforest Soils like?

- The soils are red in colour and rich in iron.
- They have a thick layer of litter (dead leaves etc) as trees drop their leaves all year round but only a thin fertile layer because the leaves decompose very quickly in the humid conditions.
- The soils are not very good for plants to grow in as nutrients are quickly washed out (leached) of the soil because of heavy rainfall.
- Trees and other vegetation have roots close to the surface, where the nutrients are - there are lots of roots in the humus layer.

What is the Interdependence of Climate, Soil and Water in Tropical Rainforests?

Warm and wet climate means that plants grow quickly - the dense leaf cover protects the forest floor from wind and heavy rainfall, while root systems hold the soil together stopping it being eroded.

What is the Interdependence of Plants in Tropical Rainforests?

Lack of wind near the forest floor means that many plants rely on bees, butterflies or other animals for pollination.

What is the Interdependence of Plants and Animals in Tropical Rainforests?

Symbiotic relationships between plants and animals (where they depend on each other for survival) are very common. For example, agouti (a rodent) are one of the only animals who can crack open the hard seed pod of the Brazil nut to eat the nut inside. Sometimes, the agouti buries the nuts - these can sprout into new seedlings. If the agouti become extinct, the Brazil but trees would also decline and so could all the other animals who live in or feed on the Brazil nut trees. People who sell Brazil nuts for a living would also be affected.

What is the Interdependence of Epiphytes in Tropical Rainforests?

Epiphytes are plants that grow on other plants. They get access to light but growing high up on other plants, but they don't have access to the nutrients in the soil - they are dependent on rainfall to provide water and nutrients.

What is the Interdependence of Human Activity in Tropical Rainforests?

Changes to the rainforest ecosystem have knock-on effects on the whole system. For example, deforestation reduces the amount of carbon dioxide being absorbed from the atmosphere which adds to the greenhouse effect and changes the climate.

What is the Value of Tropical Rainforests?

- trees reduce the flood risk as leaves intercept and slow down the rainwater. This reduces the time it takes water to reach and soak into the ground.
- they maintain some of the world's most fragile soils, protecting them from erosion.
- it provides a habitat for a wide range of flora and fauna, some of which are endangered e.g. orang-utan.
- they provide a source of income for indigenous people through agriculture and tourism.
- they help maintain the water cycle, pumping moisture into the atmosphere, providing the globe with greater defence against extreme weather. They provide most of the world's rainfall and form a cooling band around the Equator.
- they are the 'lungs of the planet'

How are Tropical Rainforests the 'Lungs of the Planet'?

They absorb carbon dioxide, store carbon and give out oxygen. This photosynthesis means that forests are an important carbon sink (store). Cutting down and burning the tropical rainforests removes this important store and sends vast amounts of carbon into the atmosphere. Deforestation is responsible for 25% of the world's carbon emissions whereas car, planes and factories only contribute 14%.

What 5 Human Activities occur in Rainforests?

- Logging
- Agriculture
- Mineral Extraction
- Tourism
- Energy Production

What is the Effect of Logging on the Rainforest?

This is the most widely reported cause of deforestation in tropical rainforests. Trees are cut down to create commercial items such as furniture, paper, doors and household utensils. Many companies would argue that they only cut down some trees but many more are damaged in the process.
With no trees to hold the soil together, heavy rain washes away the soil (erosion). This eroded soil can enter rivers, silting up habitats that fish use for breeding. The removal of trees also disrupts the water cycle - this can lead to some areas becoming very dry with an increased risk of wildfires, whilst other areas become more at risk from flooding. Logging also requires the felling of trees for road construction which further opens up the rainforests for development/destruction.

What is the Effect of Agriculture on the Rainforest?

The number of cattle ranches in the northern regions of the Amazon have increased significantly; the number of cattle outnumber people by 10 to 1. Around 80% of Brazil's deforested areas are being used for cattle ranches. It is very popular as it is relatively low risk compared to cash crops such as palm oil plantations. Palm oil is one of the most profitable cash crops for developing countries. It is found in about half of all products sold in supermarkets, from supermarkets from margarines and cakes to shampoos and cosmetics. It is also used to create fuel.
Land is often cleared using the slash-and-burn technique. Burning vegetation produces carbon dioxide, which adds to the greenhouse effect. The ability of the rainforest to store carbon is also reduced at the same time. Without tress to intercept rainfall, more water reaches the soil. Nutrients are washed away so soil fertility is reduced (they usually lose their fertility in 3-5 years).

What is the Effect of Mineral Extraction on the Rainforest?

Gold, copper, diamonds and other precious metals and gemstones are found in rainforests. Areas are also been surveyed for oil and gas reserves. The money countries make through their mineral wealth give funds for infrastructure projects such as electricity and roads in developing regions. However, there are many environmental problems.
Mining of precious metals often requires heavy machinery and the removal of trees. Heavy chemicals are used to extract and purify the metals which are washed (leached) into streams and rivers, killing wildlife and polluting people's drinking water. There can also be conflict with local people over rights to land.

What is the Effect of Tourism on the Rainforest?

Mass tourism leads to building of hotels in fragile areas and can have a significant negative impact on the relationship between local communities and the government. Tourism can also drive road construction.
Tourists may scare wildlife (e.g. causing nesting birds to abandon their young). They may also damage vegetation and leave behind lots of litter. If tourism is unregulated, a lack of infrastructure e.g. sewers, can lead to water becoming polluted. However, to build infrastructure trees must be cleared.

What is Effect of Energy Production on the Rainforest?

Dam building is common along rainforest rivers to produce hydro-electric power. As a result of this, thousands of people are forced to leave their land and large areas of the rainforest are flooded.
The problems dams create for indigenous people include disruption to the natural river system; as a result of silt being trapped behind dams, fewer nutrients are supplied to land downstream for the small-scale agricultural practices of local people. Habitats are also destroyed leading to possible extinction of some species.

What is the Climate of the Arctic?

- Average summer temperatures <10c
- Winter temperatures around -20c to -40c
- Annual precipitation <500mm
- Winds blow strongly

What is the Climate of Antarctica?

- Colder than the Arctic
- Summer temperatures around -20c to -5c
- Winter temperatures can reach almost -90c
- Annual precipitation is lower, around 50mm inland and 200mm on the coast
- Windiest continent

What are the Features of the Land and Sea of the Arctic?

- Majority of the Arctic is made up of ocean, lots of drifting ice packs and iceberg. Sea ice extends further in winter
- On land there are mountainous regions, areas that are permanently covered with snow and ice, and areas of treeless tundra (where only a surface layer of the soil thaws each summer).
- Large areas of permafrost (ground which has been frozen for a few years). When the top few centimetres thaw it produces a landscape with many depressions which fill with lakes. Marshland and boggy ground cover large areas. The soil flows when it thaws out and is not stable.

What are the Features of the Land and Sea of Antarctica?

- Continent (land mass) which is 99% covered by an ice sheet.
- A few mountains poke out of the top of the ice sheet (nuntaks) e.g. Transantarctic Mountains.
- Sea freezes in winter, nearly doubling the size of the continent.

What are the Flora and Fauna of the Arctic?

- Whales, seals, fish, wolves, polar bears, reindeer, caribou and lots of birds
- Most animals have adapted to specific conditions of the Arctic (sub-zero temperatures and absence of liquid water)
- Low-growing shrubs, lichen, moss, some flowering plants e.g. Arctic poppies
- Plants like dwarf willow and lichens cling to the ground surface to avoid being damaged by strong winds.
- Some species have natural 'anti-freeze'
- Southern fringes of the Arctic have taiga, large expanses of coniferous forest but these disappear with distance north along a line called the tree line.

What are the Flora and Fauna of the Antarctica?

- Less vegetation than the Arctic, there are two species of grass which are found in a few places, otherwise only algae and lichen can survive
- Sea contains lots of phytoplankton
- Whales, seals, penguins, seabirds
- All animals rely on the sea e.g. for food or to provide a habitat for breeding
- Penguins nest on ice shelves and Emperor penguins spend the winter there as well. Most other species migrate north to avoid the extremes of the winter cold
- Marine creatures, including penguins, avoid the extreme temperatures found inland so most biodiversity is found at sea or around the coast.

What is the Interdependence of Climate in Polar Regions?

- Cold, dry climate means low biodiversity in both the Arctic and Antarctica

What is the Interdependence of Water and Plants in Polar Regions?

- Ocean currents and wind create gaps in the sea ice which increases light levels in the water. This means algae and other producers can produce more food causing populations of fish (e.g. cod) to increase which then supports consumers such as seals, penguins and polar bears.

What is the Interdependence of Animals in Polar Regions?

- If temperatures increase (e.g. due to climate change) more sea ice melts in the summer. Animals such as seals and polar bears rely on sea ice for breeding and hunting so if it disappears these animals are threatened.

What is the Interdependence of Soil in Polar Regions?

- In the Arctic tundra, cold temperatures cause plants to grow and decompose slowly. This means the soil is low in nutrients further reducing growth rates. In the summer, the surface layer of the soil thaws and plant cover increases. Plants absorb heat from the sun and prevent the permafrost below from thawing. Slow melting of the upper layer provides liquid water for plants.

What is the Interdependence of Plants in Polar Regions?

- In Antarctica, there are very few plants. Phytoplankton in the sea are the most important producers and form the basis of all food chains. (e.g. phytoplankton > krill > fish > penguins). Phytoplankton depend on nutrient-rich currents of seawater rising to the surface from deep underwater; if this doesn't happen the whole ecosystem would be threatened.

How does Scientific Research impact Polar Ecosystems?

Scientists use polar environments for research purposes (e.g. on climate change). This can have a positive impact on global environmental management and management of polar regions. In the past, some scientists in Antarctica have left rubbish in the sea and abandoned broken equipment. This polluted the land and sea, damaging habitats and posing a risk to wildlife. Research stations and ships produce chemical and sewage pollution; however, organisations are trying to limit this.

How do Indigenous People impact Polar Systems?

There are no permanent residents in Antarctica and the Arctic has a population of approximately 4 million people. Traditional indigenous people in the Arctic rely on reindeer herding or fishing and hunting to support themselves and their families. They only take what they need so don't upset the balance of the ecosystem. Many indigenous people now live in towns and cities (e.g. Anchorage, Canada). These urban areas impact the environment through waste disposal, air and noise pollution from vehicles, and heat from buildings which melts permafrost.

How does Mineral Extraction impact Polar Ecosystems?

There are large oil and gas reserves in the Arctic (e.g. Prudhoe Bay, Alaska) as well as other mineral deposits (e.g. uranium and phosphate in Russia). Drilling for oil and gas is risky; oil spills are difficult to clean up and can harm habitats and wildlife. Pipelines have been built to transport oil and gas which melt the permafrost below and disrupts the migration routes of caribou herds. The extraction of metals from mined rocks produces a lot of pollution, damaging local ecosystems.

How does Tourism impact Polar Ecosystems?

Both the Arctic and Antarctic are popular tourist destinations. Tourism increases shipping and air travel, leading to water and air pollution. There is also a risk of boats grounding, which can cause oil spills. Tourists disrupt breeding colonies of birds and seals. Trampling damages fragile vegetation and erodes the landscape, leaving paths. As decomposition rates are so slow in the cold temperatures, litter and waste disposal damages habitats and threatens wildlife. In Antarctica especially, there is concern over the introduction of non-native species which could alter food webs, changing the ecosystem irreversibly.

How does Fishing impact Polar Ecosystems?

The Arctic waters provide 70% of the world's white fish catch and commercial fishing takes place in both polar regions. Over-fishing threatens many species (e.g. in Antarctica the Patagonian toothfish has been fished to near extinction). Reduced fish populations have knock-on effects on other species in the food chain (i.e. the larger fish and birds that eat them). Some species are also affected by getting caught in fishing lines and drowning (e.g. albatross).

How does Whaling impact Polar Ecosystems?

Many countries were once involved in whaling in the Southern Ocean. South Georgia was a whaling station and still bears the scars of the industry. Many species of whale were hunted to near extinction (e.g. blue, fin and mink whales). Whales are very slow breeders, so it takes a long time for their population to recover. Whaling has mostly stopped but some countries (e.g. Japan) still hunt whales in polar regions.

What is Svalbard?

- Svalbard is a group of islands in the Arctic Circle, north of Norway, that is promoting sustainable tourism/
- Over 60% of Svalbard is protected. For example, there are strict limits on the use of off-road motorised vehicles, and tour operators and visitors have to get permission to visit the nature reserves.
- Different zones have different levels of protection - nature reserves allow very little access, while tourism areas have fewer regulations.

What is the example of Sustainable Management in Svalbard?

Ny-Ålesund is the most northerly settlement in the world and is run by a company called Kings Bay AS. The populaiton is mostly made up of scientific researchers. The company and researchers have taken actions to limit the impact of tourism on the area.

What are examples of Actions taken in Ny-Ålesund?

- Cruise ships are required to tell passengers about the rules visitors have to follow e.g. not disturbing nesting birds or leaving litter.
- Visitors have to stick to the 1.5km path around settlement and there are lots of boards with environmental information, to make tourists aware of the issues.
- The ships are only allowed to remain anchored for a few hours - this reduces the amount of pollution from e.g. diesel fumes entering the local environment.

What is the Antarctic Treaty?

The Antarctic Treaty is an agreement originally made by twelve countries in 1959 about how to sustainably manage Antarctica's ecosystems. By 2016 53 countries had signed the agreement.

What are the Six Basic Principles for Human Activity?

- no mineral exploitation
- plants and animals must be conserved
- areas of the environment must be protected
- there are rules for waste disposal and waste must be minimised
- there are regulations for the discharge of sewage from vessels
- activities must have an Environmental Impact Assessment before they are able to go ahead

What does the Antarctic Treaty do?

- There are also strict rules about the introduction of non-native species so ecosystems aren't disturbed (e.g. visitors must wear disinfected over boots when they land and there are restrictions on eating, drinking and going to the toilet whilst ashore). The use of sledge dogs is no longer allowed (they were first used by the explorers, Amundsen and Shackleton, and scientists have used them since for companionship and to pull sledges). All dogs were removed from Antarctica by 1994 as it was thought they might spread disease to seals or attack native wildlife.
- There are also globally agreed rules amongst tour operators - only 100 visitors are allowed to land at any one time and cruise ships of over 500 passengers are prevented from stopping.
- There have been no major problems with the treaty and some people think it should be extended to cover the ocean surrounding Antarctica so that there is more protection for marine life (e.g. whales and fish).