unit 5

Created by

Liv Stark

Cards (44)

what is a biome?
ecological community whose global distribution corresponds with climatic regions off the earth
what 2 variables determine biome distribution?
temperature and precipitation
what is the distribution and climate of tropical rainforests?
across the equator eg South America, middle of Africa
hot & wet humid climate
what is the distribution of temperate grasslands?
around Tropic of Cancer & Capricorn 30 degrees north & south of equator southern Europe and North America
warm temperatures with low rainfall
what factors determine carbon stored in each biome?
size of surface
seasonal changes
soil type
vegetation coverage
how does carbon flow between ecosystem stores?
co2 from atmosphere to green plants through photosynthesis which is consumed by animals and transferred to carbon in litter due to excretion/death then to soil through decomposition
Carbon is returned to atmosphere through respiration of plants & animals
what is leaching?
removal of soluble nutrients in water percolating downwards through the soil
how does light in tropical rainforests influence plant growth and carbon storage?
lots of light increases photosynthesis, plant growth and carbon storage
similar levels all year round leading to sustainable plant growth
how does temperature in tropical rainforests influence plant growth and carbon storage?
high temps, increases photosynthesis, plant growth and carbon storage
average temp of 26.4 degrees
how does precipitation in tropical rainforests influence plant growth and carbon storage?
heavy rainfall in winter, lighter in summer, increased carbon storage in summer with trees having large leaves to catch water for transpiration
how much carbon do tropical rainforests store globally?
550 gigatones as they are a global carbon sink
how is amount of energy produced by photosynthesis measured?
gross primary productivity
how do you measure carbon stored?
amount of new biomass produced each year (net primary productivity)
which is gross primary productivity - energy lost in respiration
NPP measured in g C m-2 yr-1
rainforest averages around over 2000
what is the carbon efficiency in rainforest?
40%
why are rainforests important in global carbon cycle?
maintain global carbon balance
take out 25% of human produced carbon from atmosphere
describe the biomass store in rainforest?
highest store/largest
optimal conditions for photosynthesis
describe the litter store in rainforest.
small store
decay pathway is high due to warm humid conditions
not many plants meet end of cycle at same time
describe the soil store in rainforest?
small store
leaching & weathering is high
lots of rainfall
what human activity is in rainforests?
deforestation
during last 50 years how much of rainforests have been deforested?
1/3 of rainforests due to increasing demand for resources from increasing in size and affluence of population leading to
timber harvesting of valuable hardwoods
creating land for agriculture for cattle ranching and crop production
what is a case study for deforestation and palm oil plantations?
Borneo, indonesia as since 1950 it has lost half of tropical rainforest for logging and palm oil plantations
why does deforestation turn rainforest from a carbon sink into a carbon source?
carbon is released by dead wood and from soil
palm oil production replaces rainforests- huge loss of biomass
how much precipitation does rainforest typically receive per year?
2000mm
what process is operated on forest flor aided by high levels of rainfall?
decomposition
what affect does deforestation have on levels of runoff and litter layer and soils?
increases levels of runoff as there is less interception
increased leaching, decomposition and risk of flooding
what affect does deforestation have on levels of evapotranspiration and rainfall?
less transpiration and interception, surface run off removes and loses nutrients from soil
what is a way global atmospheric co2 levels can be reduced?
afforestation
what is a case study of afforestation?
ecosia, after signing Paris agreement, Brazil pledged to reduce co2 emissions by 43% by 2030. ecosia is helping by planting 1 million trees as only 8% of forest remains
what are the dominant vegetation species in temperate grasslands?
grass, shrubs and wildflowers
eagles, bison and birds of prey
why do fires occur naturally in temperate grasslands?
dry and hot conditions which small spark from thunderstorm can alight
how does fires help maintain the grassland?
keeps grass short and puts carbon in soil
why is tree growth restricted in temperate grasslands?
presence of herds of grazing animals
fire which burns vegetation
lack of rainfall which is insufficient to support large water dependant vegetation
how does light influence plant growth & carbon storage in temperate grasslands?
suns rays are concentrated in the summer but weaker in winter, some days only 6 hours of daylight so seasonal variations in plant growth & carbon storage
how does temp influence plant growth & carbon storage in temperate grasslands?
mean temp varies between 22 degrees in summer to -5 in winter
how does precipitation influence plant growth & carbon storage in temperate grasslands?
low average annual rainfall of 500mm spread evenly through the year
why is net primary productivity low in temperate grasslands?
600 per year, due to seasonal variations, higher temp in summer shows increased photosynthesis whereas photosynthesis reduced in winter due to lower temps
why is biomass low in temperate grasslands?
not enough consistent rainfall to keep vegetation, constant grazing prevent sit from gorging and wildfires burn grasslands reducing biomass
why is soil the largest store in temperate grasslands?
built up overtime from seasonal decay, root networks help strengthen structure to protect from erosion
why is leaching low in temperate grasslands?
due to low levels of precipitation
what human activity is involved in temperate grasslands?
large scale intensive and mechanised cereal production