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BIOL*3060 PCE > Test 3 > Flashcards

Test 3 Flashcards

1
Q

Mechanistic Definition of Ecosystems

A

The interactions between organisms and their environment, fuelled by complex fluxes and transformation of energy

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2
Q

Ecological Definition of Ecosystems

A

The processes by which biological communities absorb, adsorb, transform, and store energy

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3
Q

How are humans shaping Global Environmental Change

A

Human driven shifts in the pool sizes and flow rates of limiting resources, especially CO2, N, and P

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4
Q

What are the three components regulating flow of energy, water, and nutrients through and within ecosystems

A
  1. Primary Production
  2. Energy Flow
  3. Nutrient Cycling
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5
Q

Primary Production

A

The fixation of energy by autotrophs, typically plants, algae, and cyanobacteria
- energy is then converted into organic forms, making it available up the food chain

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6
Q

Primary production is measured as the ___ of biomass creation through time

A

Rate

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7
Q

Peak standing biomass is not directly equivalent of production because… (3)

A
  1. it is collected in one single point in time
  2. It misses losses accrued prior to the peak of plant growth.
  3. It misses below-ground processes
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8
Q

Gross Primary Production (GPP)

A

The total energy fixed regardless of any cost involved with energy fixation

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9
Q

Net Primary Production

A

The energy left over after autotrophs have met their energetic needs
- (NPP = GPP - respiration)
- NPP is what is available to consumers

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10
Q

Net primary production most strongly varies by…

A

Temperature and precipitation, and nutrient availability

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11
Q

What conditions are generally most productive

A

Warm and Moist

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12
Q

__ and __ are tightly linked, having effects that are ___ on productivity

A
  1. N
  2. P
  3. Additive
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13
Q

How are N and P co-limiting

A

Pants are unable to thrive if even one of them is in higher abundance

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14
Q

Liebig’s Law of the Minimum

A

NPP is only as great as the availability of the most limiting resource

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15
Q

Ecological Stoichiometry

A

The balance of energy and elements influencing living systems

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16
Q

Only ___ of the energy in one level of the trophic pyramid transfers upward towards the next

A

~10%

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17
Q

What are 3 key takaways from the Hubbard Brook Trophic “Pyramid”

A
  1. Animals make up an incredibly small amount of the total energy in a typical ecosystem
    - all mammals, amphibians, reptiles, birds <1 kcal m^-2
  2. Most energy is lost in an ecosystem
  3. The entire system is incredibly energy inefficient
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18
Q

1st law of thermodynamics

A

Energy is transferred but not created

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19
Q

Can biological life influence the creation of energy within an ecosystem?

A

No

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20
Q

Can biological life influence the flow of energy and resources within an ecosystem?

A

Yes

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21
Q

Disease (fight for energy)

A

Any disorder that affects how biota influences energy flows

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22
Q

Populations (Disease and the fight for energy)

A

Virulence ranges widely frim benign to lethal - classic ‘trait variability’ within populations, in both the invader and the host.

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23
Q

Environment (Disease and the fight for energy)

A

Virulence determined by age and habitat suitability - age specific and location specific mortality

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24
Q

Strong co-evolutionary adjustments (Disease and the fight for energy)

A

Reducing virulence - ongoing and sometimes rapid arms-races

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25
Outbreaks (Disease and the fight for energy)
co-evolutionary chain broken
26
Intense species interaction would be classified as _____ control of energy
Top-down
27
Bottom-up control of productivity
The abundance of organisms at a trophic level is determined by the rate o f food production for them to eat.
28
Intense resource limitation would be classified as _____ control of energy
Bottom-up
29
Top-down control of productivity
Predators affect the abundance of their prey
30
Trophic Cascade
Changes in abundances at one trophic level can influence energy flow at multiple trophic levels
31
Keystone Species
Impacts disproportionate to their biomass
32
Dominant or "foundation" species
Impacts derive from their high biomass
33
More species rich and trophically complex systems are _____ at regulating resource flows and the size of resource pools
More efficient
34
One of the leading arguments for conservation of biodiversity is...
Ecosystem Function
35
What is an "Ecosystem Function"
Process preformed by an ecosystem, where biological activity shapes the pool size and flow rates of limiting resources
36
Are ecosystem functions equivalent to ecosystem services (which are functions that are beneficial to humans)?
Yes, they tend to be
37
More diverse communities = ____ ecosystem function
Greater
38
Diversity is beneficial in a community because (2)
1. Diverse communities more efficiently consume limiting resources 2. As diversity increases there are fewer resources available for invasive species (newly recruiting)
39
Diversity-function relationships emerge because...
More species have more unique ways of intercepting, handling, and transferring energy both within and across tropic levels
40
How do monocultures impact ecosystem function?
Monocultures are 1. Unstable (density dependent) 2. Inefficient (many resources left unconsumed)
41
How can monocultures exist?
We farm to stabilize and offset inefficiencies
42
Niche "complementarity"
Community NPP is highest when all limiting resources are fully exploited
43
Portfolio Effect
Expresses the fact that stability in aggregate community properties such as biomass productivity generally rises with species diversity
44
Regardless of environmental variability...
There are always one or a few species doing well
45
Nutrient Definition
Any element required for development, maintenance, and reproduction
46
Macro Nutrient
Needed in large supply The world's Macronutrients: - Carbon - Nitrogen - Phosphorus - Hydrogen - Oxygen - Some argue potassium
47
Micro Nutrients
Needed in small supply, but still essential
48
Micronutrients play critical roles in... (4)
1. Catalyse redox processes 2. Form enzyme-substrate complexes 3. Enhance enzyme reactions 4. Play a role in protein synthesis
49
Energy generally makes a _____ through the ecosystem
One way trip
50
Nutrient cycles _____ in an ecosystem
Can be used repeatedly
51
Nutrient cycling in the tropics is ___
rapid
52
Where can nutrient cycling 1+2 occur 3. What can nutrient cycling involve
1. Cycling can occur at various spatial scales 2. can occur in both abiotic and biotic pools 3. Can involve core elements being transferred in different forms
53
Plant species create ____ feedbacks with patterns of nutrient cycling in natural ecosystems
Positive
54
Plants in nutrient-poor ecosystems...
- grow slowly - use nutrients efficiently - poor quality litter that decomposes slowly and deters herbivores
55
Plants in nutrient rich ecosystems...
- Grow rapidly - Produce degradable litter - sustain high rates of herbivory
56
Mineralization
The conversion of organic forms of N into mineral forms
57
Immobilization
Conversion of mineral to organic
58
Ammonification
When soil microbes decompose organic matter, releasing ammonia (NH4)
59
Nitrification
Conversion of NH4 to NO3, by other types of microbes
60
Can plants access atmospheric N directly?
No they rely on microbial processes or humans
61
____ costs dictate the cost of food. Why?
Fossil fuel - this is because the production of hydrogen gas required for ammonia synthesis largely comes from natural gas.
62
Many organic N fertilizers originated as
Inorganic N fertilizer
63
Intensification
Increasing cropp yields by chemicals, mechanization, and crop breeding
64
Extensification
Increasing crop yields by farming more land
65
as intensification costs rise, farmers shift to _____
Extensificaiton
66
Why makes phosphorus an important element in the natural world
It is critical for biological growth
67
Where is phosphorus most abundant
- Geological formations - Can also be found fairly abundantly in oceans and water ways
68
True or False: Phosphorus is abundant in the biosphere
False
69
What makes the phosphorus cycle overall one of the slowest biogeochemical cycles
Phosphates move quickly through plants and animals However, The process that move phosphorus through soil and the oceans are very slow
70
In terrestrial systems, bioavailable P mainly comes from...
Weathering phosphorus-containing rocks
71
Plants assimilate phosphorus as ____ and incorporate into _____
Phosphate, Organic compounds
72
N and P are _____ in most plant metabolic processes
co-dependent
73
Phosphorus limitation by competition with Bacteria
Bacteria convert plant available phosphate into organic forms that are then not available to plants. - Other bacteria make phosphate available by mineralization, although this contribution is small
74
Phosphorus Limitations by pH
Inorganic phosphorus compounds need to be soluble to be taken up by plants. This depends on acidity - must be between pH of 4-8 to ensure it is abundantly available to plants
75
Phosphorus limitations by Adsorption
Inorganic phosphorus can be chamically bound to soill particles making it unavailable to plants
76
What is the most important process controlling terrestrial P bioavailability
Phosphorus retention by soil minerals
77
Phosphorous is sticky (in soil) making it highly susceptible to...
Soil Erosion
78
Consequences of Over-enrichment of phosphorus
Pollution in lakes and streams caused by runoff can lead to large algae blooms - death an decay of blooms lead to eutrophication
79
Decomposition
When complex molecules are broken down into simpler ones
80
Degradation
The biotic based enzymatic transformation of organic carbon compounds that results is smaller molecules
81
Humification
When SOM is further broken down through the non-biotic processes of weathering, freeze-thaw cycle, and erosion
82
The Oxygen Factor
Most biological activity is oxygen dependent, meaning most nutrients cycling (and roots) are in the top 30-50 cm of the earth's soils (depending on soil porosity)
83
Decomposition is...
one of the largest carbon fluxes
84
N is associated with soil C accumulation, due to the combination of (2)
1. Higher tissue quantity (more litter inputs) 2. Accumulation of microbial derived polymers
85
Leaf litter varies tremendously in...
Chemical composition - changes in the species composition of leaf litter could profoundly alter decomposition
86
Nutrient-poor ecosystems (decomposition)
plants grow slowly, use nutrients efficiently and produce poor quality litter that decomposes slowly and deters herbivores
87
Nutrient-rich Ecosystems
Plant grow rapidly, produce readily degradable litter and sustain high rates of herbivory, further enhancing rates of nutrient cycling
88
Carbon mineralization
In soil refers to the microbial based decomposition of organic carbon into inorgainic forms, primarily carbon dioxide, which is then released into the atmosphere
89
Carbon Seqestration
In soil is (mostly) the plant based capture, removal and storage of CO2 from the atmosphere

BIOL*3060 PCE (3 decks)

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