IB Environmental Systems and Societies/Biomes
2.4 Biomes
[edit | edit source]2.4.1 Define the term biome.
- A collection of ecosystems sharing similar climatic conditions; for example, tundra, tropical rainforest, desert.
- Int: Biomes usually cross national boundaries (biomes do not stop at a border; for example, the Sahara, tundra, tropical rainforests).
2.4.2 Explain the distribution, structure and relative productivity of tropical rainforests, deserts, tundra and any other biome.
- Tropical Rainforests:
- High productivity
- High precipitation (2500 mm yr¹) throughout the year
- High insolation
- High temperature (26 ʻC)
- Good nutrient cycling = High rate of decomposure
- Highest NPP
- Temperate Forests:
- Medium productivity
- 4 seasons (Insolation and temperature varies)
- Good growing season in the summer but limited in the winter
- High temperatures and insolation in the summer = Greater productivity
- Rainfall between 500 and 1500 mm yr¹
- Second highest NPP
- Tundra:
- Low productivity
- Lowest of precipitation (50 mm yr¹)
- Low insolation (Days are shorter)
- Low Temperature
- Poor nutrient cycling because itʼs locked in the permafrost therefore low rate of decomposure
- For 1-2 months the productivity is very high because the sun is up for almost the whole day
- Deserts:
- Very low productivity
- Low precipitation (Under 250 mm yr¹)
- High insolation, but all water is evaporated or absorbed by the ground
- Hot days & Cold nights
- Low nutrient cycle
- Species adapted to survive
- Grassland:
- Wide diversity, but low levels of productivity
- Enough precipitation to prevent deserts forming, but not enough to support forests
- Nutrient cycle is sufficient
- Insolation, precipitation and evaporation rates are balanced
- Grass can grow under the surface even in cold periods, waiting to emerge until the ground warms