Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Ecology and Ecosystems > 2. The Soil Ecosystem > Flashcards

2. The Soil Ecosystem Flashcards

1
Q

What is soil? 3

A
  1. Thin mantle over surface of earth 2. interface between gaseous atmosphere and rocky lithosphere 3. where terrestrial life is sustained
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Define lithosphere. 1

A
  1. crust and upper layers of upper mantle of earth
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What are the abiotic components of soil? 4

A
  1. Minerals 2. Water 3. Gas - spaces allow water, nutrients and other gases to travel and interact with organisms 4. Other nutrients
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What are the biotic components of soil? 3

A
  1. Meso and macrofauna eg. oligochaetes, nematodes, athropods and molluscs 2. Microfauna ef. protozoa, algae, microbes 3. Viruses
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What are horizons in terms of soil? Include diagram. 7

A
  1. Different layers/strata are called horizons
  2. Horizon composition determines soil type
  3. fresh litter is not decomposing, or is in early stages
  4. Organic is decomposing matter
  5. biotic material found in first 3 layers
  6. huge global soil diversity
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Describe tropical soils. 4

A
  1. very deep - large profile
  2. old and weathered
  3. little organic material, just a thin later on top
  4. most biomass in first 3 cm and above
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Describe desert soils. 3

A
  1. No organic component
  2. minimal vegetation
  3. weathered
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Describe tundra soils 5

A
  1. arctic and antarctic
  2. permafrost beneath thin soil layer
  3. organically rish
  4. not productive, can’t support much life due to temp
  5. small growth window and little decomposition
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Describe british and mancunian soils. 5

A
  1. range across britain
  2. mancunian range from free-draining to quite wet
  3. generally wet and acidic
  4. can have raised or blanket peat bog soils
  5. 2 soil types cover 60% of UK: brown earths and gley soils
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Describe brown earth soils. 6

A
  1. general to well drained
  2. moderately deep - good mixing between organic (F+H) and mineral (A) layers
  3. found under temperate grasland and deciduous forest, also good for agriculture
  4. high biotic activity, especially earthworms
  5. high rates of decomposition and nutrient availability
  6. brown colour form iron oxides (fe3+)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Describe gley soils. 5

A
  1. periodic water logging
  2. mineral (B) horizon compact with few large pores
  3. water logging leads to anaerobic conditions so less productive than brown earth soils
  4. red markings indicate plant life due to oxidation of iron
  5. generally blue green/grey from microbial reduction of ferric (fe3+) to ferrous (fe2+) iron
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Describe podzolic soils. 7

A
  1. also important in uk
  2. free draning, sandy parent material
  3. beneath coniferous forest and heathland
  4. very deep and acidic organic (F+H) horizon

5, acidic water leaches nutrients

  1. Dark brown surface layer, bleached, nutrient poor organic horizon, and lower horison with iron, aluminium and other nutrients
  2. low productivity, lacks earthworms
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

How is parent material formed and how does it influence soil variation? 6

A
  1. weathering of rock (biotic/abiotic)
  2. mineral components (acidic/basic)
  3. grain size (sand, silt or clay) impacts h20/nutrient availability
  4. pH determines what can grow there
  5. less acidic means more life
  6. freeze-thaw or lichen colonization, which produces acid therefore erosion, can influence mineral layer
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What is the soil triangle? 2

A
  1. Best growing soils are in the middle
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

How does climate inflluence the variation of soils? 5

A
  1. association between regional climates, vegetation and soil
  2. less important in old soils eg. tropical (2m year old) and young soils eg. Britain 15 000yr old from glacial deposits
  3. important in temperate areas
  4. temp and rainfall impact - warmer and wetter means more decomposition, faster chemical reaction rates
  5. biological growth rate doubles every 10 degrees until 35 degrees celcius
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

How does topography influence the variation in soils? 4

A
  1. moving downhill, water table rises compared to durface level
  2. influences soils
  3. less well draining approaching river
  4. brown earths and podzoic soils become gley towards river
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

How does time influence the variation in soils? 7

A
  1. More weathering with age
  2. more highly differentiated layers
  3. leaching of minerals and nutrients downwards (podzolisation)
  4. incrase of soil organic matter - why tropicals are so deep
  5. more N, less phosphorous - both needed for plant growth
  6. As animals colonize, N increased, then plataeu
  7. Phosphorous levels increase, then bound into soil matrix so not available
18
Q

What is the composition of soil biota? 8

A
19
Q

How do plant roots affect the soil structure? 6

A
  1. Anchor vascular plants
  2. conduit for nutrients and water
  3. grow about 2cm daily. pushing all soil particles and creating gaps
  4. obligate requirement for aerobic conditions
  5. Fix and secrete carbon - support other llife
  6. secrete mucus and deposit cells, changing rhizosphere
20
Q

What is the rhizosphere? 5

A
  1. Area of soil surrounding root that is affected by its activities
  2. reduced water potential here as net flow towards roots, creating a nutrient gradient
  3. Increased carbon changes ion composition and pH
  4. Increased microbial abundance, providing food for protozoa
  5. Causes increaed protozoa abundance
21
Q

How do fungi change the structure of the soil? 7

A
  1. Dominant soil microbes (greater biomass than bacteria)
  2. Grassland soils have about 250kg fungal hyphae per hectare
  3. Less species rich than bacteria
  4. most of biomass underground
  5. hyphal structure facilitates colonization, utilisation and mobillisation of organic matter and nutrients
  6. princple role in degradation of organic matter
  7. symbiotic and pathogenic relationships with plants
22
Q

Why are bacteria important in the soil? 4

A
  1. most numerous and diverse microbes in soil (1010-1011/g soil)
  2. limited mobility
  3. degradation of organic matter by production of extracellular enzymes
  4. important in element cycling, especially nitrogen
23
Q

What is the importance of soil in carbon cycling? 4

A
  1. Most carbon is in lithospheric and aquatic deposits eg. caco3 in oceans
  2. this is not acrive
  3. soil contains most mobile carbon
  4. also sound in atmosphere and live organisms
24
Q

What is the carbon cycle? 5

A
25
Q

What is primary productivity? 5

A
  1. Rate at which energy from the sun is stored
  2. Main contributers are plants, algae and cyanobacteria
  3. main flux of carbon from atmoshphere to soil
  4. variation wtih ecosystem
  5. can be measured by measuring plant growth
26
Q

What are the differences in primary productivity between ecosystems? 6

A
  1. Colder environments mean less carbon is fixed
  2. less fixed in grass than trees
  3. curring down forests releases carbon but more released by ploughing grassland which is done regularly for agriculture
27
Q

What is the nitrogen cycle? 5

A
28
Q

What is nitrogen fixation? 8

A
  1. Process of making ammonia from elemental nitrogen
  2. Nitrogen enters soil via lightening/bacteria
  3. N2 + 8H+ + 8e- -> 2NH3 +H2
  4. Can be symbiotic via nodules
  5. Can be non-symbiotic by:
  6. Obligate aerobes - need oxygen
  7. Obligate anaerobes can’t have oxygen
  8. Facultative aerobes prefer oxygen but not essential
29
Q

What is nitrification? 4

A
  1. Nitrates are the most bioavailable form of nitrogen
  2. Nitosomonas spp: 2NH3 + 3O2 -> 2NO2- + 2H2O + 2H+
  3. Nitrobacter spp: 2NO2- + O2 -> 2NO3-
  4. Denitrification is the removal of oxygen from nitrogen compounds to make ammonia
30
Q

Fundamentals of Ecology, Odum and Barrett. 2005. Give some extra detail about the nitrogen cycle. 8

A
  1. Breakinf down proteins to nitrates provides bacteria wiht energy
  2. Creating proteins from nitrates requires energy input
  3. Oxidation of ammonia to nitrites to nitrates provides bacteria with energy
  4. Ammonium, nitrite and nitrate can be used by plants, but nitrate is more expensive as special enymes are required to convert it to ammonium
  5. Some bacteria fix nitrogen in the ocean in temperate zones
  6. May be free-living or symbiotic
  7. Enzyme nitrogenase splites N2 in n-fixation
  8. Less efficient in terrestrial free living bacteria than symbiotic
31
Q

The Biology of Soil. R. D. Bardgett. 2005. What is the importance of parent material in determining soil properties? 3

A
  1. Parent material can be from the rock below or sediments carried there
  2. The rock determines the qualities and minerals of the soil
  3. eg. basic larva soils are high in calcium, magnesium and posassium with fine texture - fertile brown earths
32
Q

The bIology of soil. R. D. Bardgett. 2005. How does climate influence the properties of soil? 3

A
  1. Temperature and rain have a greater effect at high altitudes and latitudes.
  2. Organic matter increases with latitude, until beyond the treeline, then declines
  3. Decomposition reduced due to lower temp
33
Q

The biology of soil. R. D. Bardgett. 2005. How does topography influence the properties of soil? 2

A
  1. Steep parts of hills have shallow soils
  2. lower soils are finer as these particles are moved here by erosion
34
Q

the biology of soil. R. D. Bardgett. 2005. How is stable soil formed? 6

A
  1. Freeze thaw/ shrinkage and swellig moulds soil
  2. rain and ploughing reorganizes soil
  3. burrowing animals mix organic and mineral horizons to create stable organo-mineral complexes
  4. faeces aere centres for aggregate formation
  5. roots and microbes produce slimes that hold everything together
  6. aggregation and structure determine pore distribution
35
Q
A
36
Q
A
37
Q
A
38
Q
A
39
Q
A
40
Q
A
41
Q
A

Ecology and Ecosystems (18 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions