Unit 5 Notes Flashcards
(121 cards)
1
Q
What is a Biome?
A
An ecological community whose global distribution corresponds with climatic regions of the earth.
2
Q
What are the climatic variables which determine biome distribution?
A
Annual Precipitation, Average Temperature.
3
Q
What is the distribution of tropical rainforests?
A
Distribution - Concentrated along the equator, extend to the tropics.
4
Q
What is the Climate of tropical rainforests?
A
Precipitation - 250mm to 450mm. Temperature - Between 20-30 degrees.
5
Q
What are the examples of tropical rainforests?
A
South East, Central America, Amazon, West Africa.
6
Q
What is the distribution of temperate grasslands?
A
Between 30-50 degrees N and S of the equator.
7
Q
What is the climate of temperate grasslands?
A
Temperature ranges from 0-20 degrees. Precipitation ranges from around 0mm to 120mm per year.
8
Q
What are the examples of temperate grasslands?
A
South America, North America, Central Asia.
9
Q
How is Carbon stored in an ecosystem?
A
Carbon is an essential plant macronutrient, makes up 44% of the dry weight of plant biomass globally. Total amount of Carbon stored in biosphere is estimated to be 3000 gigatons.
10
Q
Where is carbon stored in an ecosystem?
A
Green Plants, Animals, Litter, Soil.
11
Q
How is Carbon stored in Green Plants?
A
Nearly 20% of Carbon in Earth’s Biosphere is stored in plants, including root systems below soil surface.
12
Q
How is Carbon stored in Animals?
A
These play a small role in carbon storage, because biomass of animals is less than plant biomass.
13
Q
How is Carbon stored in Litter?
A
This is fresh and un-decomposed plant debris on the surface of the soil - includes leaves, other dead organisms and excrement.
14
Q
How is Carbon stored in Soil?
A
Hummus is a black substance remaining in the soil, after most organic litter has decomposed - it is dispersed throughout the soil by earthworms.
15
Q
What % of Carbon is stored in global biomes?
A
Tropical Forest - 28%. Tropical and Subtropical Grassland - 15%. Deserts - 9%. Temperate Grasslands - 9%. Temperate Forest - 16%. Boreal Forest - 15%. Tundra - 8%.
16
Q
What happens to Carbon dioxide in the atmosphere?
A
Photosynthesis - Goes to carbon in green plants.
17
Q
What happens to Carbon in animals?
A
Respiration - Goes to carbon in the atmosphere.
18
Q
What happens to Carbon in Green Plants?
A
Death + Leaf Shedding - Goes to carbon in litter.
19
Q
What happens to Carbon in litter?
A
Decomposition - Goes to carbon in soil.
20
Q
What happens to Carbon in Animals?
A
Excretion + Death - Goes to carbon in litter.
21
Q
Which factors affect the amount of Carbon stored in each biome?
A
Amount of living matter per unit area, size of the surface it covers.
22
Q
What is a Gersmehl Diagram?
A
A standard way of representing the movement of all nutrients within an ecosystem.
23
Q
What are the inputs into the litter layer?
A
Input dissolved in rainfall, fall out as tissues die.
24
Q
What are the outputs from the litter layer?
A
Release into soil as litter decomposes, loss in runoff.
25
What are the inputs into the soil layer?
Input from weathered rock, release as litter decomposes.
26
What are the outputs from the litter layer?
Uptake by plants, loss by leaching.
27
What are the inputs into the biomass layer?
Uptake by plants.
28
What are the outputs from the biomass layer?
Fall out as tissues die.
29
What is Leaching?
The removal of soluble nutrients in water percolating downwards through the soil.
30
What is different about uptake by plants?
Doesn't relate to carbon. Plants don't take in carbon from soil.
31
How does light in Tropical rainforests influence plant growth?
More sunlight = more photosynthesis = more carbon taken in = more plant growth.
32
How does temperature in Tropical rainforests influence plant growth?
Stays consistent. High seed germination. New growth all year round due to increased carbon storage.
33
How does Precipitation in Tropical rainforests influence plant growth?
High levels of precipitation all year round - high carbon storage.
34
Which part of the Rainforest store over 550 gigatons of Carbon?
Very high levels of photosynthesis, and high carbon storage in the biomass of a tropical rainforest.
35
What is GPP?
Gross Primary productivity. The amount of energy produced by photosynthesis in a unit area during one year.
36
What is NPP?
Net Primary Productivity. The amount of new biomass produced each year.
37
What is NPP measured in?
Grams of carbon per square metre per year.
38
What is the average NPP of a rainforest?
2000 g c m-2 yr -1.
39
What is the average NPP of a deciduous forest?
1000 g c m-2 yr -1.
40
How big is the rainforest biomass?
700 tonnes per hectare.
41
What are the different layers of a rainforest?
Emergent layer, canopy, Under canopy, shrub layer.
42
What are the characteristics of the emergent layer?
Can grow over 30 metres tall, waxy leaves.
43
What are the characteristics of the canopy?
Absorbs 80% of sunlight. Most photosynthesis takes place here.
44
What are the characteristics of the under canopy?
Smaller trees limited plant growth, such as low lying lianas and ferns.
45
What are the characteristics of the shrub layer?
Warm, dark and wet - litter rapidly decomposes - 2% of sunlight hits shrub layer.
46
What is the Carbon efficiency of rainforests?
40-50%.
47
How much Carbon do rainforests store?
2-3k per hectare per year.
48
Why are rainforests important in the global carbon cycle?
Rainforests absorb 1/4 of the anthropogenic carbon we produce, important carbon sinks.
49
How big is the carbon store in the tropical rainforest?
The largest store, very high levels of photosynthesis, high carbon storage. 2-3 kg degrees per year fixed in the ecosystem. Sunlight doesn't vary much during the year.
50
How big is the soil store in a tropical rainforest?
Smaller than biomass due to leaching, where nutrients are rapidly taken out of soil, and percolation of water. Presence of detritivores leads to rapid decomposition.
51
How big is the litter store in a tropical rainforest?
The smallest store of carbon, as precipitation runoff occurs due to the waxy layers of leaves, and the release of carbon, as litter decomposes.
52
What % of tropical rainforests have been deforested during the last 50 years?
1/3.
53
Why has deforestation increased?
Increased demand from a growing global population.
54
What does deforestation lead to?
Timber harvesting of valuable tropical hardwoods such as mahogany and teak. Creating land for agriculture - cattle ranching, crop production.
55
What was the % of deforestation from different countries between 2000-2005?
Brazil - 27%. Indonesia - 17%. Myanmar - 4%. Zambia - 4%. Venezuela - 3%.
56
What is the case study of loss of tropical rainforests?
Borneo, Indonesia.
57
How many tons of carbon are stores in the primary forest?
3000 tons.
58
How much does deforestation reduce the carbon store by?
1/2.
59
How much of the rainforest is left, compared to original amounts?
Less than 10%.
60
What happens to GPP as a result of deforestation?
It falls, as there are less leaves, and stumps are taken over.
61
What happens to atmospheric carbon as a result of deforestation?
It increases.
62
What could happen to rainforests after deforestation?
Can turn rainforests from a carbon sink to a carbon source, as there is reduced ability for photosynthesis, as well as left behind detritivores, which release C02.
63
How much palm oil is stored in palm oil plantations?
20-30 tons per hectare.
64
How much rainfall does a tropical rainforest receive per year?
200-450 cm.
65
What leads to leaching in a tropical rainforest?
Drip tips, and a high level of rainfall, due to the weight of water.
66
Why are soils heavily leached of nutrients?
Due to decomposition and high levels of rainfall, which reach the shrub layer due to deforestation.
67
What happens to interception after deforestation?
Less rain is intercepted, increasing surface runoff, meaning rain goes straight to the forest floor. The amount of nutrients decreases.
68
Why does deforestation lead to soil erosion?
It removes the litter layer.
69
Why does deforestation also lead to a drier climate?
There is less convectional rainfall.
70
What does a reduction in convectional rainfall lead to?
Less water vapour, and less transpiration.
71
What leads to transpiration in a tropical rainforest?
Dense vegetation.
72
What is the case study for palm oil plantation destruction?
Indonesia.
73
What happened in Indonesia in the 1990's?
A palm oil company was promised wealth and development, as a result of larger companies taking control of the community's ancestral land, and get half of it back. They were left with nothing.
74
How does biomass change when deforestation occurs?
Trees logged and removed. No longer part of the carbon cycle of Tropical rainforests.
75
How does the output of crops change when deforestation occurs?
Increased rainfall reaching surface increases crop growth.
76
How does precipitation change the Tropical rainforest, after deforestation occurs?
Deforestation reduces a rainforests' ability to photosynthesise, there is an increased amount of dead organic matter. This breaks down, releasing C02.
77
How is there increased runoff as a result of deforestation?
Rain will reach surface layer quickly due to less interception. Increases runoff, removing litter layer.
78
How is there increased leaching as a result of deforestation?
Once the litter layer is gone, more runoff will lead to soil erosion, leading to higher levels of leaching. Deforestation will decrease, and evaporation and rainfall leads to less interception. High levels of rainfall increases throughflow and stemflow.
79
How is Ash affected as a result of deforestation occuring?
If burnt nutrients enter the soil as ash, they're used in crops or washed, or leached through soil.
80
What are the different projects of Aforestation around the world?
UN-REDD programme - Aims to reduce emissions from deforestation and forest degradation in developing countries. Ecosia - Use their search engine to give profits to Afforestation projects.
81
What did Brazil pledge to do to carbon emissions?
2016 - Brazil pledged to voluntarily reduce C02 emissions by 43% by 2030.
82
How are Ecosia helping Brazil?
Planting 1 Million trees during 2019, on the East Coast of Brazil.
83
What are the changes in the stores after Afforestation takes place?
Biomass store increases, soil store increases, Litter layer increases due to runoff decreasing.
84
What happens to flows after Afforestation takes place?
Less infiltration, more interception, leading to less soil erosion. Runoff decreases. Crop harvest increases.
85
Where are Temperate Grasslands found?
Between 30-50 degrees N and S of the Equator.
86
Where are the main locations of Temperate Grasslands?
Prairies of plains of USA and Canada. Steppes of Eurasia from Ukraine to Mongolia. Pampas of Argentina and Uruguay.
87
What is the climate of Temperate Grasslands?
Hot wetter summers, cold drier winters. Slightly higher levels of precipitation during summer months, due to convectional rainfall.
88
What is the dominant vegetation species of Temperate Grasslands?
Grass.
89
What are the main animal species of Temperate Grasslands?
Gazelles, Buffalos, Prairie dogs, Hamsters.
90
What happens to fire in Temperate Grasslands?
Fires naturally occur, as lightning causes grass fires. Ash which is generated returns to the soil, returning nutrients to the soil.
91
Why does the grassland maintain itself?
Presence of herds of grazing animals, fire which sporadically burns vegetation. A lack of rainfall, insufficient to support large water dependent vegetation.
92
How does Light influence plant growth?
The sun's rays are concentrated during summer at these latitudes, but are much weaker during winter months, when there may be no more than 6 hours of daylight. Results in marked seasonal variations in plant growth.
93
How does Temperature influence plant growth?
Mean monthly temperature in Mariupol varies between 22 degrees in summer, and -5 degrees in winter. Temperature grasslands at high altitudes or closer to the coniferous forest boundary may experience an even more extreme temperature range.
94
How does precipitation influence plant growth?
Low average annual rainfall of around 500mm or below in much of the biome, spread evenly throughout the year. There is a substantial build up of winter snow in temperate grasslands found at higher northern latitudes.
95
What is the productivity of Temperate Grasslands?
600 g, compared to 2000g of Tropical rainforests.
96
What happens to the amount of biomass in a temperate grassland?
Less than a Tropical rainforest, where it's 70kg/m. TG - 1.6kg/m.
97
Why is NPP low in Temperate Grasslands?
Only up to 6 hours of daylight in winter. Sun is lower, less intense, build up of winter snow, frozen ground.
98
Why is Biomass low in Temperate Grasslands?
Not many plants growing, and at one level. Grass, low density, grazing animals, fires, lack of rainfall.
99
Why is the biomass small in Temperate grasslands?
Cold winters and short growing seasons. Insufficient moisture to support large trees. Photosynthesis is seasonal, limited by small scale vegetation.
100
Why is the litter layer small in Temperate Grasslands?
Grasses decay slowly into soil. Biomass is held in form or roots beneath the ground. Litter transfers nutrients to soil.
101
What happens to nutrients in Temperate Grasslands?
Large amounts of bacteria, litter releases organic matter into soil. Roots of grasses are effective at storing nutrients and water - uptake from soil to biomass.
102
What happens to biomass in a natural system?
Natural grasses eaten by herbivores and carbon returned to litter in excrement. Fire burns vegetation and returns carbon to soil as ash. Seasonal die back of grasses returns carbon to litter.
103
What happens to biomass in an intensive farming system?
Modified crops grown as monocultures are harvested: biomass removed from system. Monoculture crops need to be sprayed with chemical pesticides to avoid pest infestation. Pesticides use fossil fuels in their production.
104
What happens to litter in a natural system?
Litter gains carbon inputs from excrement and seasonal die back of grasses. Litter slowly decomposes to release carbon soils.
105
What happens to litter in an intensive system?
As biomass is removed, only crop stubble is left. Litter layer is greatly depleted.
106
What happens to soil in a natural system?
Inputs from the decomposition of excrement and dead plant material, and ash from fires result in organic carbon rich soil. Soil bound together by permanent deep rot system of perennial grasses.
107
What happens to soil in an intensive farming system?
Limited inputs of organic matter result in soil becoming depleted of organic matter, reducing carbon store. Artificial chemical fertilisers required to maintain productivity, as organic content of soil diminishes.
108
Is a natural Temperate Grassland system a net carbon source or store?
Net Carbon Store.
109
Is an Intensive farming system a net carbon source or store?
Net Carbon Source.
110
What is the case study for top soil disappearance?
Iowa.
111
What happened to top soil in Iowa during the 20th century?
It went from 14-18 inches to 6-8 inches - A 10-12 inch decrease.
112
What % of the world's land has been taken over by agriculture?
40%.
113
What happens to barley crop roots, compared to natural temperate grassland vegetation?
They extend by 0.5m, which goes down 3m.
114
What is the case study of Drought and soil erosion in the USA?
Dust bowl - Midwest USA. 1934-1939.
115
How much land was affected in Midwest USA?
100 Million Acres, centred on Texas and Oklahoma, affected NM, Colorado and Kansas.
116
How was Soil Erosion made worse?
By poor farming practices that removed the natural drought tolerant grasses, and exposed the soil.
117
What else happened to topsoil due to Soil erosion?
Caused millions of tons of topsoil to erode due to strong winds. Led to 2.5 Million people abandoning their farms.
118
What happens to stores after human activity in Temperate Grasslands?
Biomass reduces - Diversity changes, harvesting of crops, root length reduces. Soil is smaller due to soil erosion - due to soil erosion, and wind. Less litter being removed - less decomposition.
119
What happens to flows after human activity in Temperate Grasslands?
Crop removed in part of the year. Crop is still smaller. Less decomposition. Less transfer, less fires, less organic matter. Iowa has lost 25cm of soil.
120
What happens to Tropical rainforests as a result of Human Activity?
Change to both water and carbon cycle as a result of intensive farming.
121
What happens to Temperate Grasslands as a result of human activity?
Change to carbon, not water cycle, as a result of intensive farming.
