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 lowtemperatures 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 temperaturesincrease 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
Lowtemperatures and waterlogging slow decomposition and respiration and the flow of CO2 to the atmosphere
Lowtemperatures, lack of liquidwater 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 PrimaryProductivity (200 grams/m2/yr)
Low biomass
How does photosynthesis affect the Tundra's carbon cycle?
Sequestration of CO2low
During summer there is rapidgrowth 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 temperaturesslowphotosynthesis 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 limitedwater and sunlight