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Biophysical > biosphere > Flashcards

biosphere Flashcards

1
Q

soil organisms

A

‘biological engine of the earth’, drive and modulate key processes in soil

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2
Q

attributes of soil organisms that support high soil biodiversity

A
  • fast growth rates and high dispersal rate
  • horizontal gene transfer
  • dormancy
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3
Q

Kaolinite

A

lower surface area

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4
Q

Montmorillonite

A

higher surface area

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5
Q

tree of life

A

a taxonomic approach to diversity revealing dominance of bacterial genetic diversification

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6
Q

classification of soil biota by size

A

microflora and microfauna

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7
Q

photoautotroph

A

energy source: light

carbon source: carbon dioxide

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8
Q

photoheterotroph

A

energy source: light

carbon source: organic compounds

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9
Q

chemoautotrophs

A

energy source: chemical compounds

carbon source: carbon dioxide

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10
Q

chemoheterotrophs

A

energy source: chemical compounds

carbon source: organic compounds

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11
Q

what are microbes made up of?

A

70-85% water

50% protein (dry mass)

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12
Q

what do microbes need to grow

A
  • favorable environment
  • water
  • mineral nutrients
  • energy sources
  • election donors and acceptors
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13
Q

Biomass C:N

A

8-12 bacteria

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14
Q

biomass C:N (fungi?)

A

30 fungi

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15
Q

bacteria’s traits that define a microbes ‘nice space’

A
  • cell wall
  • morphology
  • metabolism
  • oxygen requirements
  • plasticity
  • substrate preferences
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16
Q

obligate aerobe

A

oxygen is required

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17
Q

facultative anaerobe

A

oxygen is preferred, but not required

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18
Q

obligate anaerobe

A

oxygen is toxic, TEA required

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19
Q

microbes make extracellular enzymes to…

A

break down organic compounds so they can assimilate them

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20
Q

mycorrhiza

A
  • symbiosis between a fungus and a plant (root)

- one of the oldest symbiotic relationships

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21
Q

key attributes of fungi

A
  • heterotrophs
  • key players in decomposition
  • multicellular
  • fungal spores develop from hyphae
  • cell walls made of chitin
  • prefer slightly acidic soils
  • sensitive to disturbance
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22
Q

fungal hyphae

A
  • thin filaments making up the fungus

- grow at the tips and branch out

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23
Q

Mycelium

A

mass of hyphae

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24
Q

wood rot fungi

A

primary decomposers of complex structural organic matter like lignin

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25
Q

bacterial growth rate…as pH increases

A

increases

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26
Q

fungal growth rate…as pH increases

A

decreases

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27
Q

Alfalfa

A

rich in nitrogen (C:N<20)

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28
Q

Straw

A

less available N, good for fungal growth

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29
Q

soil fauna regulate what microbial processes

A
  • Comminution
  • translocation
  • inoculation
  • predation
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30
Q

comminution

A

fragmentation of material (jump start microbial decomposition)

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31
Q

translocation

A

movement of materials

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32
Q

inoculation

A

movement of microbes

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33
Q

predation

A

grazing on microbes

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34
Q

Bioturbation

A

mixing and rearrangement of the soil

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35
Q

Dormancy/resting states have been linked with..

A

maintenance of biodiversity

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36
Q

microfauna

A
  • <100 micromm, predators of microorganisms

- diverse set of feeding preferences

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37
Q

nematodes

A
  • soil microfauna
  • occupy multiple trophic levels
  • feed on plant roots, bacteria, and fungi
  • aquatic
38
Q

Mesofauna

A
  • 100-200micromm
  • soil predators
  • pathogens
  • herbivores
39
Q

major functions of mesofauna

A
  • regulations of bacterial, fungal and microfaunal populations
  • nutrient cycling
  • transport of materials
  • alter litter decomposition rate
  • contribute to soil development
  • bicontrol agents
40
Q

macrofauna

A
  • > 2mm
  • soil predators
  • herbivores
  • ecosystem engineers
41
Q

rhizosphere

A

the zone of the root’s influence on the soil

42
Q

why do food webs matter

A
  • provide info about species richness, population sizes, resource niches, and how species’ populations are regulated
  • estimate the amount of C and N mineralization facilitated by different
  • understand how a change in a food resource will alter energy flows and nutrient availability
43
Q

predator C:N

A

> 1 nitrogen mobilization

44
Q

resource C:N

A

<1 nitrogen immobilization

45
Q

does fear increase or decrease nitrogen content

A

decrease

46
Q

AMF (arbuscular mycorrhizae)

A
  • grows inside plant cells
  • spores are located outside
  • inorganic nitrogen but mostly P
  • obligate symbionts
47
Q

EMF (ectomycorrhiza)

A
  • grows in between plant cells
  • do not penetrate cells like AMF
  • fruiting bodies
  • larger hyphen network compared to AMF
48
Q

mycorrhizae

A

-contribute to soil C storage

49
Q

Herbivory

A

consumption/removal of plant tissue

50
Q

below ground impacts of herbivory

A
  • changes plant productivity and C allocation
  • changes resource quality
  • soil physical properties
51
Q

negative feedback

A

slows down or diminishes a system process. Tends to stabilize a system

52
Q

positive feedback

A

increases a system process. Tends to drive the system to a new state

53
Q

herbivory can be positive or negative depending on…

A
  • site
  • herbivores
  • plant community
54
Q

herbivory, grazing effect

A
  • can be good for grasslands, reinforcing fertility and plant productivity
  • plant community succession slows
55
Q

SOM (soil organic matter)

A

foundation of ecosystem productivity, soil quality, agricultural sustainability

56
Q

SOM consists of:

A
  • plant residues at various stages of decay

- soil microbes, fauna, and their by-products

57
Q

Primary SOM constituents

A
  • proteins, amino acids, nucleic acids
  • carbohydrates
  • phenolics
  • lignin
58
Q

how root inputs persist

A
  • chemical recalcitrance
  • physical protection
  • physio-chemical protection
59
Q

how does litter decomposition happen?

A
  1. physical fragmentation
  2. leaching of soluble compounds
  3. chemical transformation/enzymatic breakdown
60
Q

process of decomposition

A
  1. fragmentation
  2. further fragmentation
  3. extracellular enzymes of biological origin, complex polymers
  4. extracellular enzymes, producing monomeric units
61
Q

factors affecting SOM levels

A
  1. climate
  2. vegetation
  3. land use
  4. climate change
62
Q

physical protection

A

inaccessibility to decomposition

63
Q

chemical-physic protection

A

-mostly based on binding mechanisms between SOM and minerals

64
Q

SOM = ….

A

inputs - outputs

65
Q

SOM inputs:

A

plant productivity

66
Q

SOM outputs:

A

mineralization

67
Q

SOM pools

A
  1. active, labile, fast cycle, biologically available
  2. free or within aggregates
  3. held tightly onto clay minerals and metal oxides
68
Q

pool 1 function

A

energy, nutrients for plants and microbes

69
Q

pool 2 function

A

soil structure, nutrients

70
Q

pool 3 function

A

C sequestration

71
Q

least protected mechanism for SOM accumulation

A

chemical recalcitrance and abiotic constraints

72
Q

most protected mechanism for SOM accumulation

A

chemical/physio protection

73
Q

how to enhance SOM levels

A
  1. add continuous supply of high quality organic matter
  2. add legumes to crop rotation
  3. reduce tillage when feasible
  4. use perennial vegetation when feasible
  5. maximize plant growth
74
Q

N cycle

A
  1. mineralization
  2. nitrification
  3. denitrification
  4. leaching
  5. N2 fixation
75
Q

Nitrogen

A

a scarce resource that often limits primary productivity in many ecosystems

76
Q

nitrogen cascade

A

undergoes many different transformations, changing from one form to another as organisms use it for growth and energy

77
Q

Reactive N is linked to…

A

multiple ecosystem and human health issues

78
Q

Mineralization

A
  • organic Nitrogen to NH4 (ammonium)

- can sometimes turn in to nitrification if converted to NO3

79
Q

Nitrification

A
  • ammonium–>NO2 (nitrite)–>NO3 (nitrate)

- aerobic process

80
Q

Denitrification

A
  • conversion to gaseous N
  • if not completed, N2O is the product which is potent
  • anaerobic process
  • returns inorganic nitrogen to the atmosphere
81
Q

N2 fixation

A
  • atmospheric N2–>NH4

- nitrogenase is the enzyme that catalyzes the reduction of N2 to NH3

82
Q

assimilation

A
  • uptake of inorganic N into organic biomass

- can be microbial, soil biota, or plant assimilation

83
Q

controls on soil N concentrations depend on what two processes?

A

mineralization and assimilation rates

84
Q

controls on soil N concentrations

A
  1. inorganic N
  2. immobilization
  3. organic N
  4. mineralization
85
Q

BNF

A

biological nitrogen fixation

86
Q

controls and limitations on N fixation rates

A
  • physiological
  • soil properties
  • ecological
  • energy and nutrient constraints
87
Q

nitrogen pools

A
  1. ammonium
  2. nitrate
  3. nitrite
88
Q

some global change factors

A
  1. increased drought
  2. increased precipitation
  3. warmer temperatures (one of the biggest factors)
  4. erosion
89
Q

Why is canada warming faster than other places?

A
  • loss of snow and sea ice, so less reflection and more retention of heat
  • larger surface warming
90
Q

Albedo

A
  • indicated how well a surface reflects solar energy

- the more a surface absorbs heat, the lower the number value of Albedo

91
Q

what is predicted on precipitation in canada?

A
  • winter precipitation expected to increase and more so in the north
  • summer precipitation expected to decrease

Biophysical (2 decks)

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