unit five: carbon stores in different biomes

Question 1

what is a biome?

Answer 1

an ecological community whose global distribution corresponds with climatic regions of the earth

Question 2

where are tropical rainforests located and what is their climate like?

Answer 2

• between the two tropics (23.5 degrees north and south)
• high temperatures with lots of rainfall annually (2500mm) = high humidity

Question 3

where are temperate grasslands located and what is their climate like?

Answer 3

• 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)

Question 4

where is carbon stored in an ecosystem?

Answer 4

• 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

Question 5

how will light in tropical rainforests affect plant growth and carbon storage?

Answer 5

• 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

Question 6

how will temperature in tropical rainforests affect plant growth and carbon storage?

Answer 6

higher temperatures = keep foliage = store more carbon

Question 7

how will precipitation in tropical rainforests affect plant growth and carbon storage?

Answer 7

• needed for growth
• too much = soil erosion = increase runoff = leaching

Question 8

how much carbon do tropical rainforests store globally and how much does the amazon rainforest store per year ?

Answer 8

550 gigatons annually with amazoon storing 1.7 billion tonnes

Question 9

what is a rainforests’ average net primary productvity?

Answer 9

2000 g C m^2 yr^-2

Question 10

how much carbon does tropical deforestation release per year?

Answer 10

1.5 billion tonnes per year

Question 12

what is the structure of a tropical rainforest and each layers features?

Answer 12

• 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

Question 13

why are rainforests important in the global carbon cycle?

Answer 13

• 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

Question 14

what are the differences in the size of the biomass, litter and soil stores in tropical rainforests?

Answer 14

• 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

Question 15

over the last 50 years, how much tropical rainforest has been deforested and why?

Answer 15

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)

Question 16

how many tons of carbon are stored per hectare in the primary forest?

Answer 16

300-500 tonnes

Question 17

what affect does deforestation have on the carbon store and the gross primary productivity?

Answer 17

• photosynthesis decreases = gpp decreases
• removing large amount of biomass

Question 18

why does deforestation turn from a carbon sink to a carbon source?

Answer 18

• tree stumps left = respire and break down = release more carbon dioxide
• can’t be planted with other vegetation

Question 19

how many tons of carbon are stores per hectare in palm oil plantations?

Answer 19

up to 30 tonnes

Question 20

where is deforestation occurring, to use the land as palm oil plantation?

Answer 20

bornea, indonesia

Question 21

why are rainforest soils heavily leached of nutrients?

Answer 21

excess water strips soil of nutrients (runoff)

Question 22

what affect does deforestation have on levels of runoff and the litter layer and soils?

Answer 22

• less interception = increased runoff and washed away organic layer
• loss of root structure

Question 23

what affect does deforestation have have on levels of evapotranspiration and rainfall?

Answer 23

decreases = precipitation changes = water cycle changes (rainforests produce their own rain)

Question 24

what happened in indonesia in the 1990s linked to palm oil?

Answer 24

• 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

Question 25

what is the afforestation case study scheme?

Answer 25

• ecosia
• planting 1 million trees during 2019
• specific search engine that plants trees with every search

Question 26

what are the dominant vegetation species and main animal species in temperate grasslands?

Answer 26

• grasses with trees being absent (not enough precipitation)
• gazelles (2 million in mongolia), bisons (were close to extinction), grazing animals

Question 27

why do fires naturally occur and how might this help maintain the grassland?

Answer 27

• dry due to lack of precipitation
• lightning strike can cause fire
• ash can be beneficial to nutrient layer
• decomposers like the warmth

Question 28

how does light influence plant growth and carbons storage in temperate grasslands?

Answer 28

seasonal variations = marked seasonal variation in plant growth and biomass carbon storage

Question 29

how does temperature influence plant growth and carbons storage in temperate grasslands?

Answer 29

mean monthly temperature varies between 22 degrees in summer to -5 degrees in winter

Question 30

how does precipitation influence plant growth and carbons storage in temperate grasslands?

Answer 30

low average (500mm) and winter snow in higher northern latitude areas = limiting factor for tree growth

Question 31

what is the net primary productivity in temperate grasslands?

Answer 31

600 g C m^-2 yr ^-1

Question 32

why is productivity and biomass low in temperate grasslands?

Answer 32

• npp: grassed store less carbon, due to not as much photosynthesis taking place. there aren’t any trees = less respiration as well
• biomass: no trees, only grasses = less biomass

Question 33

what is the impact on biomass in a natural system and a mechanised, intensive farming system in temperate grasslands?

Answer 33

natural system:
- natural grasses eaten by herbivores and and carbon returned to litter in excrements
- fire burns vegetation and returns carbon as ash
- seasonal die back of grasses returns carbon to litter

intensive farming system:
- monocultures harvested = biomass removed
- pesticides use fossil fuels in their production and application

Question 34

what is the impact on litter in a natural system and a mechanised, intensive farming system in temperate grasslands?

Answer 34

natural system:
- litter gets carbon input from excrement and seasonal die back of grasses
- litter decomposes = release carbon into soil

intensive farming system:
- as biomass removes, only crop stubble left
- litter layer is greatly depleted

Question 35

what is the impact on soil in a natural system and a mechanised, intensive farming system in temperate grasslands?

Answer 35

natural system:
- inputs from decomposition of excrements and dead plant matter, and ash from fires
-soil bound together by permanent deep root system of perennial grasses

intensive farming system:
- limited inputs = depleted matter
- artificial chemical fertilisers used to maintain productivity as organic soil content diminishes
- chemical fertilisers use fossil fuels in production and application
- loss of deep root system (ploughing) means soil is prone to wind erosion during dry weather

Question 36

what is the impact on carbon in a natural system and a mechanised, intensive farming system in temperate grasslands?

Answer 36

natural system = net carbon store

intensive farming system = net carbon source