Section 2

• An ecosystem is a natural system made up of plants, animals and the environment
• Producer -> organisms that get their food from the natural environment
• Consumer -> organisms that feed on other organisms
• Decomposers -> feed on dead producers and consumers, they break down litter and recycle the nutrients back to the soil
• Herbivores only eat plants, carnivores eat only animals, omnivores eat both
• Food chain -> single link of linkages between the producers and consumers
• Food Web -> shows all linkages between the producers and consumers in an ecosystem
• Nutrient cycle -> movement of nutrients around an ecosystem
• A freshwater ecosystem is an example of a low-scale ecosystem in the UK. Producers = algae, Marsh marigold, waterlily. Consumers = frog, heron, fish, duck, waterworks, rat tailed maggot
• Deserts are found along the tropic of Cancer and Capricorn (e.g. Sahara desert). The climate is is arid (hot and dry), temp ranges from 40°c at day and less than 5°c at night, less than 250mm rainfall per year.
• Deserts have very sparse vegetation and very few animals. Soil in the desert isn't very fertile, soil in deserts are usually shallow, dry and has a coarse, gravelly texture. Indigenous people in the desert are usually nomadic farmers who travel with their herd (goats and sheep) in search of food and water.
• Biodiversity is the variety of organisms living in a particular area. Deserts have low biodiversity - small areas os desert are near water.
• Some threats to the desert are desertification as this causes deserts to get bigger and soils become drier = erosion. Climate change creates more extreme weather = plants/animals are unable to survive = less biodiversity.
• Vegetation adaptations -> cacti -> some have deep roots to reach deep underground, some have very shallow horizontal roots just below the surface to aborb water before it evaporates, thick waxy skin to reduce water loss from transpiration, spines reduce water loss and protect cacti from predators

  
• Vegetation adaptations -> joshua tree -> deep roots to reach water deep under the ground, small needle like leaves to reduce water loss, leaves are covered in a waxy resin to avoid water loss

  
• Animal adaptations -> camel -> large flat fewt to spread their weight on the sand, triple eye lids and long eyelashes to keep sand put of their eyes, their colour helps them camouflage, they store fat in their hump which cam be used for energy, they can also break this fat down into water when needed

  
• Animal adaptations -> lizard -> burrow during the hot days and emerge at night to feed, colour helps them camouflage, nocturnal - only come out at night when cooler

  
• All parts if of the desert ecosystem are linked together. If one of them changed, everything else is affected. E.g. plants get nutrients from soil, animals get nutrients from plants
• The Sahara desert cam be used for mining oil and gas, they do this in Hassi Messaoud oilfield in Algeria. + 50% of algerias GDP (gross domestic product) come from oil and gas, 40000 ppl r employed for this. -= workers have to be flown to the oilfield, food and water has to be flown there
• Solar panels r built in the Sahara desert to make use of the 12+ hours of bright sunshine in the desert, this is done in Tunisia in northern america. += energy sold to western Europe = money for development, renewable energy. -= sandstorms destroy solar panels and dusty conditions means they need cleaning often - requires 10300 gallons of water a day
• Agriculture is used in the river Nile to irrigate land and grow crops, the river Nile is in Egypt. += 13%of Egypts income, employs 32%of Egypts labour force. -= rapid evaporation of irrigation water
• Tourism happens in Egypt when people visit thw world's largest desert, Egyptian culture, pyramids and camel treks. += income for development, employment, development of transport and infrastructure. -= pollution from development, overuse of water, cultures are used as entertainment rather than tourists learning about their tradition
• Development in the Sahara desert is challenging due to:

  • Extreme temperatures
  • Inaccessibility
  • Water supply
• Desertification is the process where land gradually turns into a desert. It becomes drier, less fertile and is vulnerable to erosion.
• Causes of desertification:

  • Climate change (leads to extreme weather such as droughts=plants can die=roots no longer hold soil together=erosion)
  • Over-grazing (too many cattle eat vegetation=roots don't hold soil together)
  • Over-cultivation (Over farming leads to all nutrients being used up)
  • Deforestation (roots don't bind soil together)
• How can we reduce desertification:

  • Afforestation
  • Crop rotation/grazing rotation
  • Water management
  • Appropriate technologies
• Rainforests are located along the equator. The climate in rainforests is humid (hot and wet), it had no seasons and temp ranges from 20-30°c and precipitation ranges from 160-3300mm a month
• Rainforests has very dense and varied vegetation and animals. The soil is not very fertile, as heavy rainfall washes nutrients away. This is known as leaching. Most nutrients are in the top layer of soil due to nutrients recycling from leaves.
• Rainforests have very high biodiversity. Rainforests contain around 50% of the world's plants, animals and insect species.
• Deforestation is causing a loss of biodiversity in the rainforest as mnay animals and plants become endangered or extinct.
• 1. Shrub and ground layer
  2. Lower canopy
  3. Upper canopy
  4. Emergent layer

  
• Vegetation adaptions -> trees (height, buttress roots, bark) -> trees can grow to over 40m in height to find sunlight, buttress roots help the tree support its height-acts as an anchor, trees have smooth and thin bark=water runs off easy

  
• Vegetation adaptions -> lianas -> Wood vines that use trees to climb to the upper canopy where they spread tree to tree to get as much light as

  
• Vegetation adaptions -> leaves -> on the shrub and ground layer its very dark-leaves have large surface area to catch as much light as possible, many leaves have drip tips and a waxy coating-water sheds easily, some plants (e.g. fan palm) have large fan shaped leaves that are segmented so excess water drains away easily

  
• Animal adaptations -> spider monkey -> long strong arms and tails so they can swing between the trees in upper canopy

  
• Animal adaptations -> leaf-tailed gecko and chameleon -> camouflaged so cam blend into surroundings to hide from predators

  
• Animal adaptations -> jaguar -> can swim due to high rainfall and many rivers

  
• Animal adaptations -> red-eyed tree frog -> have suction cups on their feet and hands to help them climb up trees and leaves

  
• Rainforest nutrient cycle:

  • Nutrients enter the soil
  • Shallow roots take up nutrients
  • Trees grow rapidly
  • Trees shed leaves all year round
  • Decaying vegetation decomposes rapidly
  • This repeats
• The amazon rainforest is used in a number of ways:

  • Cattle farming (clearing land for massive, commercial cattle farms-causes 70% of deforestation)
  • Logging
  • Hydro-electric energy (build dams and resevoirs)
  • Mining (for iron, copper, etc.)
  • Building roads (transport products)
  • Urban growth
  • Substinence farming (local farmers clear land using slash and burn and grow only food that's enough for their family-causes 20% of deforestation in forest)