Ecosystems

• Tundra

  • found at high latitudes
  • winters are very cold, summers are brief and there's little rainfall
  • hardly any trees
• Savanna grassland

  • found between the tropics
  • distinct wet and dry seasons
  • relatively low rainfall
  • most of the vegetation is grass with a few trees
• Temperate grassland

  • found at higher latitudes
  • variation in temperature, little rainfall
  • no trees just grass
• Temperate deciduous forest

  • found in the mid-latitudes
  • warm summers, relatively mild winters, rainfall all year round
  • trees lose their leaves during the winter to cope with the colder weather
• Tropical rainforest

  • found around the equator
  • hot and wet all year round
  • dense canopies of vegetation
• Hot desert

  • little rainfall
  • very hot during the day, very cold at night
  • shrubs and cacti are sparsely distributed in the sandy soil
• Polar

  • found around the north and south poles
  • cold, icy and dry
  • remain dark for several months each year so their growing season is very short
• Tropical Rainforests: Climate

  Hot and high rainfall
• Tropical Rainforests: Plants

  • most are evergreen
  • many trees are really tall and the vegetation cover is dense
  • there are lots of epiphytes
• Tropical Rainforests: Soil

  • Isn't very fertile due to heavy rainfall washing nutrients away
  • There are surface nutrients due to decaying leaves, but this layer is thin
• Tropical Rainforests: Interdependence

  • warm and wet climate helps fungi and bacteria on the forest floor to decompose dead plant material rapidly, making the surface soil high in nutrients, meaning plants can grow easily
  • plants pass on their nutrients when eaten by animals. The dense vegetation provides lots of food so the animal population is high
  • when animals die, their nutrients are transferred back to the soil, making it richer and encouraging more vegetation
• Tropical Rainforests: Plant Adaptations

  • trees are tall to compete for sunlight
  • plants have thick, waxy leaves with drip tips, encouraging water to run off, preventing fungi and bacteria from growing and ensuring the weight of water doesn't damage the plant
  • climbing plants (such as lianas) use tree trunks to reach sunlight
  • buttress roots support the tall trees trunks
• Tropical Rainforests: Animal Adaptations

  • some animals are camouflaged to hide from predators
  • many animals are nocturnal as the night is cooler
  • suction cups help some animals climb
  • some have flaps of skin to help them glide between trees
• Tropical Rainforests Sustainable Management

  • Replanting - new trees can be planted to replace those that are cut down
  • Selective logging - only some trees are cut down and most trees remain, which is less damaging than clearing a whole area as the overall forest structure is kept
  • ecotourism - only a small number of visitors are allowed into an area at a time and rules are imposed to minimise environmental impacts. This can raise awareness of conservation issues and bring in more money to help protect rainforests. Provides jobs for locals EXAMPLE: Lapa Rios ecotourism resort
• Tropical Rainforests Sustainable Management

  • international education - educating people can encourage them to buy products from sustainable sources.
  • local education - locals may damage the rainforest to overcome their poverty without realising the long-term effects. teaching them about alternative ways to make money means they won't be dependant on unsustainable options
  • conservation - many countries have set up nature reserves and national parks within rainforests. in these areas, deforestation is restricted, promoting sustainability. They're often funded by oversea governments
• Tropical Rainforests Sustainable Management

  • reducing debt - countries in debt may make money through deforestation in order to pay off their debt. reducing debt means that they don't need to do this and the rainforests can be conserved.
  • 'debt-for-nature' swaps - there's no guarantee that the money saved from debt will be spent on conservation, so a better solution is a conservation swap, where part of a country's debt is paid off in exchange for a guarantee that the money will be spent on conservation
• Hot Deserts

  Climate: little rainfall, extreme temperatures (hot day, cold night)

  Soil: lack of leaf fall limits soils fertility, little rainfall means soil dries out often

  Plants: plant growth is spare due to low rainfall
• Hot Deserts: Interdependence

  • plants take up nutrients from the soil and provide nutrients and water to the animals that eat them
  • animals spread seeds through their poo, helping plants reproduce
  • soils are salty due to high evaporation rates and relatively low in nutrients because there's little decomposition of dead plant material, meaning plants struggle to grow. This means that there's sparse vegetation, limiting the amount of food available, meaning the desert can only support low-density populations of animals and people
• Hot Deserts: Plant Adaptations

  • plant roots are either extremely long to reach deep water supplies or can spread out very wide near the surface to absorb as much water as possible when it rains
  • many plants have large fleshy stems for storing water
  • many plants have thick waxy skin to reduce transpiration
  • some only germinate after it rains as they'll grow quickly in these conditions
• Hot Deserts: Animal Adaptations

  • many are nocturnal
  • many animals have long limbs/ears to give them a larger surface area to lose heat from
  • many live in underground burrows where temperatures are less extreme
  • some animals store fat that they break down into water when needed
• Causes of Desertification:

  Climate Change - climate change is expected to reduce rainfall in areas that are already dry. Leads to plants dying. Global temperatures are increasing, causing more water to evaporate from the land, making soil drier
• Desertification is the degradation of land, making it drier and less productive. It occurs when vegetation dies or is removed because there are no roots binding soil together
• Causes of Desertification:

  Removal of fuel wood - many people in dry areas rely on wood as fuel for cooking. removal of trees leaves the soil exposed

  Overgrazing - too many livestock eat plants faster than they can re-grow. trampling by animals also erode the soil

  Over-cultivation - if crops are planted in the same area continually, all the nutrients in the soil are used up, meaning plants can no longer be grown in those areas

  Population growth - more people put more pressure on the land, leading to more deforestation, more overgrazing and more over-cultivation
• Sustainable Development in the Desert: The Great Green Wall

  ambition to go an 800km natural wonder across Africa's entire width
• Water Management


  • Growing crops that need little water can reduce water use
  • Using drip irrigation on crops instead of surface irrigation means that the soil isn't eroded by lots of water being added all at once
• Tree Planting


  • Can act as windbreaks, reducing wind erosion
  • Roots stabilise the sand
• Soil Management


  • Leaving areas of land to rest in between grazing or planting lets them recover their nutrients
  • Rotating crops that take different nutrients from the soil prevents the same nutrients being continually removed
• Appropriate Tech


  • Rate of deforestation can also be reduced by using solar cookers
• Reducing Risk Of Desertification

  1. Water Management

  2. Tree Planting

  3. Soil Management

  4. Appropriate Tech