Ecosystem productivity + energy flow Flashcards
What is an ecosystem?
The linking of biotic + abiotic factors in an environment w/ a defined movement of energy + matter
What are the components of an ecosystem?
Producers Consumers Decomposers Abiotic components -water -atmosphere -soil minerals
How will global warming affect distribution graphs?
Increase in temp:
- > more hot weather + less cold weather
- > less light precipitation + more heavy precipitation
What could an increase in precipitation due to global warming lead to?
Higher chance of leaching
= washes away fertiliser
Why should we care about ecosystem ecology?
> provides a mechanistic basis for understanding the Earth system
ecosystems provide good + services to society
human activities are changing ecosystems
- need to improve management
What are the core research areas in ecosystem research?
Transformation + interactions of energy + matter within an ecosystem:
- energy budgets + factors that control energy transfer
- monitoring changes over time + space
- sustainability (carrying capacity + restoration)
What is productivity?
The rate of energy capture + conversion to chemical bonds
How much solar energy is reflected/not absorbed by plants?
99%
What are the 2 type of primary productivity?
GPP
= rate at which energy is captured + assimilated by producers
- includes use of captured energy for their own metabolism via respiration
NPP
= rate of energy assimilated + converted to biomass
= GPP - respiration
How could plants be made more efficient?
Make RUBISCO more efficient
What are the 4 ways you can measure primary productivity?
- measure changes in producer biomass
- measure changes in CO2 uptake + release
- measure changes in O2 uptake + release
- remote sensing
How do you measure change in producer biomass?
Measure mass of producers at beginning + end of growing season
= estimates NPP
How do you measure changes in CO2 uptake + release?
Measure CO2 in a container in light + dark
Decrease in CO2 in light = NPP
Difference between light + dark measurements = GPP
How do you measure changes in O2 uptake + release?
Measure dissolved O2
Increased O2 in light = NPP
Difference between light + dark measurements = GPP
What is remote sensing?
Using the absorbance + reflectance of chlorophyll to map global changes in producer biomass
Describe the pattern of NPP across the globe
Not equally distributed
Terrestrial systems show highest productivity in tropics
Tropical rainforests = most productive ecosystems
Describe the pattern of NPP in aquatic systems
Marine systems = lower in productivity per unit area
Aquatic systems along coasts = highly productive
Estuaries + coral reefs = most productive
What is the relationship between precipitation + temp, with productivity?
What about between nutrients + productivity?
Postive correlation
N + P, as well as in combination, can be limiting to productivity
What is secondary production?
How much energy is fixated by the consumers
What is energy flow in ecosystems constrained by?
Laws of thermodynamics:
1st law = energy can be converted from 1 form to another but can’t be created/destroyed
2nd law = transformations of energy result in some loss/dissipation of energy
What is the consumption efficiency equation?
Consumed energy / net production of the lower trophic level
What is the assimilation efficiency equation?
Assimilated energy / consumed energy
What is ecological stoichiometry?
The study of the balance of energy and elements influences living systems
What is the net production efficiency equation?
Net production energy/ assimilated energy
What is the ecological efficiency equation?
Net production energy of a trophic level / net production energy of a lower trophic level
How does ecological efficiency explain the no. of trophic levels?
Plants avoid being consumed via defences
-> less energy moves up in trophic levels due to low consumption efficiency
= less transferred energy supports fewer trophic levels
How does the no. of trophic levels differ in aquatic ecosystems?
Algae is consumed more efficiently
-> supports more trophic levels
What is standing crop?
The amount of biomass present at a particular time in a system
What is the relationship between ecological efficiency and biomass accumulation?
Low ecological efficiency
= high biomass
What does NPP vary with?
Environmental factors
- light, temp, nutrients etc
