geog

• what is a natural hazard

  sudden, severe events which make the natural environment difficult to manage. They have huge social and economical impacts and fall into 3 groups:

  -flooding

  -atmospheric -geological
• hazard risk


  the chance of being affected by a natural hazard
• what is a geological hazard?

  hazards caused by the land on the Earth and tectonic movements eg earthquakes
• what is a meteorological hazard?


  a hazard caused by the weather atmosphere or climate eg heatwaves
• Ecosystem


  A complex natural system made up of plants, animals and the environment
• Scales of ecosystems

  • Small (e.g. pond, woodland)
  • Global (biomes)
• Components within an ecosystem

  • Producers (e.g. plants)
  • Consumers
  • Decomposers (e.g. bacteria, fungi)
  • Food chains
  • Food webs
• Nutrient cycling

  Dead plant and animal material is broken down by decomposers to add nutrients to the soil, which are then used by plants
• Freshwater pond ecosystem

  • Variety of habitats
  • Pond surface - plenty of oxygen and light, animals breathe through gills, skin or lungs
  • Above pond surface - birds breathe oxygen
  • Food found in, on or at the margins of the water
  • Mid-water - animals breathe through gills or skin, fish are main predators
  • Pond bottom - little oxygen or light, plenty of shelter and food, decomposers and scavengers live here
• what does ecosystem mean?

  A community of plants, animals and abiotic organisms sharing an environment
• what is a biome?


  a large scale ecosystem
• how are low pressure areas created

  when air rises
• a food web is..

  a network of interconnected food chains
• what is nutrient cycle


  shows how nutrients such as potassium, nitrogen, magnesium, calcium and phosphorus are transferred between the biotic and abiotic components of an ecosystem
• what are the biomes (6)

  tropical rainforest, desert, savanna, temperate deciduous forest, taiga, tundra
• the distribution of biomes is determined by..

  climate (latitude, air pressure, winds)
• in lower latitudes, around the Equator, temperatures are the…

  highest
• in higher latitudes, eg polar regions, temperatures are the..


  lowest
• what is the climate like in a tropical rainforest?

  wet, hot, humid, average daily temp of 28 degrees celsius, no seasons as climate is consistent year round
• what is the soil like in a tropical rainforest?

  not very fertile, a thin layer of fertile soil is found at the surface where the dead leaves decompose, red coloured (it is rich in iron) , heavy rainfall means nutrients are washed away quickly
• layers of a tropical rainforest

  forest floor

  shrub layer

  under canopy

  canopy

  emergent
• how have plants adapted in the tropical rainforest?

  -lianas-woody vines with roots in the ground but climb up the trees to reach sunlight. In the canopy.

  -drip tips-plants have leaves with pointy tips that allow water to run off the leaf quickly without damaging it.

  -buttress roots-large roots have ridges which create a large surface area to support large trees

  -epiphytes-plants that live on branches of trees high up in the canopy. their nutrients come from the air and water, not the soil.
• how have animals adapted to the rainforest?

  -sloth camouflages and moves slow so it is hard for the predators to spot

  -spider monkey has long strong limbs for climbing through the trees

  -toucan has long large bill to teach and cut fruit from branches that are too weak to support its weight
• reasons for deforestation in Amazon rainforest

  -farming- large areas cleared for pastoral farming. High demand for meat= more cattle farms

  -logging-trees cut down for paper, valuable trees like mahogany used to make furniture

  -mining-Amazon is rich in natural resources like gold, iron ore etc leads to development of mines resulting in clearance of forest. Carajas mine in brazil is worlds largest iron ore mine.

  -roads-need to be built in forest so farmers, loggers, miners can access

  -population- is growing. more houses and infrastructure needed so land is cleared
• impacts of tropical rainforest loss:

  -soil erosion-land cleared means soil is left bare. when it rains, the nutrients in the soil are washed away. nutrient cycle stops bc no plants are shedding leaves to replace the nutrients. soil is not fertile, the roots of plants and trees cannot hold the soil together so it is easily eroded.

  -loss of biodiversity- food web connections

  -climate change-co2 is absorbed by the trees

  -economic development- mines, farms and roads created money that can be used to generate foreign income which can pay off debts or be invested in further development projects
• how can tropical rainforests be managed in a sustainable way?

  -logging and replanting-selective logging of mature trees means the canopy is preserved. Forest recovers quickly as young trees gain more space and sunlight to grow. For every tree logged, another is replanted.

  -education-promoting the benefits of biodiversity in tropical rainforests

  -ecotourism-creates jobs for locals, money generated is used to protect the rainforest.

  -international agreements-agreements to protect tropical rainforests made between countries through debt-for-nature swaps
• what are debt for nature swaps?


  when a country which is owed money by another country cancels part of the debt in exchange for the debtor country ensuring the conservation of its tropical rainforests
• Amazon Rainforest- what happened to the forest in 2019?

  30,000 fires burned in the Amazon. Trees could die due to lack of water and release huge amounts of co2 into the atmosphere (contributed to global warming)
• how much rainfall does the rainforest receive each year?

  2,000 mm
• where are hot deserts found

  near the tropics of cancer and capricorn
• what is the largest hot desert?

  Sahara in Africa
• what is the climate like in hot deserts?

  -very hot (summer day time temps can exceed 40 degrees and night temps can drop below 0 degrees)

  -dry (less than 250mm of rain a year)

  -two distinct seasons - summer with temps between 35-40 degrees and winter with temps 20-30 degrees
• what is the soil like in hot deserts?

  thin,sandy, rocky, grey, dry (when it rains the soil soaks up the water quickly)

  Surface is crusty due to lack of rainfall (salt is left on the soil from water evaporating due to the heat)
• how have plants adapted in hot deserts?

  -small leaves (ensure less water is lost from the plant by transpiration as the leaf has a smaller surface area)

  -tap roots (long roots 7-10 metres reach deep underground to access water supplies)

  -spines (some plants have spines instead of leaves eg cactuses. Spines lose less water than leaves so are efficient in the hot climate and also prevent animals eating it.

  -waxy skin (thick, waxy skin on the surface to reduce water loss)

  -water storage(some plants-succulents-store water in their stems,leaves, roots or fruits.
• desertification definition?


  the process of land turning into desert as the quality of soil declines over time
• Causes of desertification


  • Overgrazing
  • Soil erosion
  • Climate change
  • Population growth
  • Removal of wood
• Overgrazing


  Increased population means larger desert areas being farmed, leads to soil erosion
• Soil erosion


  Made worse by overgrazing and removal of wood, population growth is primary cause of soil erosion
• Climate change


  Global climate is getting warmer, desert regions getting warmer & drier, less rain now in desert regions than 50 years ago
• Removal of wood


  Wood is used for cooking, increased population means more land cleared of trees, the roots of trees can't hold the soil together so it is vulnerable to soil erosion