Arctic Tundra - Carbon

• What are the characteristics of the Tundra's carbon cycle?

  • Permafrost is a big carbon sink - globally contains 1600 GT of carbon
  • Carbon accumulated due to low temperatures which slows decomposition of dead material
  • Carbon in soil is x5 greater than above ground
  • NPP is low - 200 grams/m2/year Small tundra biomass between 4-29 tonnes/ha
  • CO2 and methane are released from unfrozen soil and permafrost water in the winter
  • Global warming has reduced the permafrost's function as a carbon store. It is becoming a carbon source. However, warmer temperatures increase plant growth, increasing stores
• How do the flows and stores vary in the Tundra's carbon cycle?

  • Carbon is stored as partly decomposed plant remains frozen in permafrost. Locked away for 500,000 years
  • Low temperatures and waterlogging slow decomposition and respiration and the flow of CO2 to the atmosphere
  • Low temperatures, lack of liquid water and rocks containing few nutrients = limited plant growth
  • Short growing season leads to low biomass carbon store
  • Rock composition has little influence due to permeability /porosity/mineral composition
• What are some stores and flows in the Tundra?

  • Vegetation
  • Photosynthesis
  • Soil/ground
  • Atmosphere
• How does the vegetation affect the Tundra's carbon cycle?

  Low Net Primary Productivity (200 grams/m2/yr)

  Low biomass
• How does photosynthesis affect the Tundra's carbon cycle?

  • Sequestration of CO2 low
  • During summer there is rapid growth but still limited biomass for photosynthesis
• How does soil/ground affect the Tundra's carbon cycle?

  • Permafrost stores vast amounts of carbon ; although accumulation is slow, there is 5x more carbon here than above ground
• How does the atmosphere affect the Tundra's carbon cycle?

  • CO2 released into the atmosphere all year round but most during growing season via respiration
• What are the physical factors affecting the Tundra's carbon cycle?

  • Geology
  • Temperature
  • Biomass
• How does geology impact the Tundra's carbon cycle?

  • Little impact on flows of carbon cycle due to impermeability of the permafrost overlying hard crystalline rock
  • Most carbon stored in permafrost
• How does temperature impact the Tundra's carbon cycle?

  • Low temperatures slow photosynthesis and respiration, so limited flow of CO2 to atmosphere
  • Slow decomposition
• How does biomass impact the Tundra's carbon cycle?

  • Total store small due to limited water and sunlight