unit five: carbon stores in different biomes Flashcards
what is a biome?
an ecological community whose global distribution corresponds with climatic regions of the earth
where are tropical rainforests located and what is their climate like?
- between the two tropics (23.5 degrees north and south)
- high temperatures with lots of rainfall annually (2500mm) = high humidity
where are temperate grasslands located and what is their climate like?
- between the tropic and polar lands, concentrated in the northern hemisphere, at every continent bar antarctica
- lower temperatures with moderate rainfall, more seasonal variance (summer = warm, winter = cold)
where is carbon stored in an ecosystem?
- green plants (20% of carbon in earth’s biosphere in plants)
- animals
- litter (fresh and un-decomposed plant debris, including leaves, other dead organic matter and excrement)
- soil
how will light in tropical rainforests affect plant growth and carbon storage?
- regular and consistent due to the tilt of the axis
- more light = more photosynthesis = more growth = more carbon storage
- have dense canopy = on 3% of light makes it to forest floor
how will temperature in tropical rainforests affect plant growth and carbon storage?
higher temperatures = keep foliage = store more carbon
how will precipitation in tropical rainforests affect plant growth and carbon storage?
- needed for growth
- too much = soil erosion = increase runoff = leaching
how much carbon do tropical rainforests store globally and how much does the amazon rainforest store per year ?
550 gigatons annually with amazoon storing 1.7 billion tonnes
what is a rainforests’ average net primary productvity?
2000 g C m^2 yr^-2
how much carbon does tropical deforestation release per year?
1.5 billion tonnes per year
what is the structure of a tropical rainforest and each layers features?
- emergent (30-40m): waxy leaves
- canopy (20-30m): rain is intercepted, lichens, absorbs 30% of sunlight, shallow buttress roots
- under canopy (10-20m): plenty of sunlight, mostly smaller trees, low shrubs, ferns, lichens, rainfall intercepted
- shrub layer (0-10m): dark, nutrients entering soil are rapidly absorbed by vegetation, ferns, mushrooms
why are rainforests important in the global carbon cycle?
- use light energy to convert carbon dioxide into glucose and oxygen
- energy source for trees to grow
- respiration of plants and animals
- regulating the outputs of fossil fuels
- above land biomass store more carbon
what are the differences in the size of the biomass, litter and soil stores in tropical rainforests?
- biomass: big as optimal conditions for biomass to be supported, diverse range of plants = high nutrient uptake
- litter: small as trees are evergreen = little fall , decomposition happens quickly = moves quickly to the litter store
- soil: very small due to leaching or uptake by large amount of biomass
over the last 50 years, how much tropical rainforest has been deforested and why?
1/3 due to increasing demand for resources and increasingly affluent global population:
- timber harvesting to valuable hardwoods (mahogany and teak)
- crop production (cattle food, palm oil)
how many tons of carbon are stored per hectare in the primary forest?
300-500 tonnes
what affect does deforestation have on the carbon store and the gross primary productivity?
- photosynthesis decreases = gpp decreases
- removing large amount of biomass
why does deforestation turn from a carbon sink to a carbon source?
- tree stumps left = respire and break down = release more carbon dioxide
- can’t be planted with other vegetation
how many tons of carbon are stores per hectare in palm oil plantations?
up to 30 tonnes
where is deforestation occurring, to use the land as palm oil plantation?
bornea, indonesia
why are rainforest soils heavily leached of nutrients?
excess water strips soil of nutrients (runoff)
what affect does deforestation have on levels of runoff and the litter layer and soils?
- less interception = increased runoff and washed away organic layer
- loss of root structure
what affect does deforestation have have on levels of evapotranspiration and rainfall?
decreases = precipitation changes = water cycle changes (rainforests produce their own rain)
what happened in indonesia in the 1990s linked to palm oil?
- palm oil company arrived with promises of wealth and development
- took control of community to in return, get half back
- tribe would previously sell fruit harvested by community
- 25 years = palm oil grew tall = produced millions of dollars worth of palm oil
- tribe never received the small holdings they were promised
- failed to give 1/5 of earning to communities
