Ecological principles Flashcards
Define ecology
The scientific study of the interactions between organisms and their environment
What is a critical factor of ecology?
Human activities
What are two components of ecology?
Biotic
Abiotic
What does biotic mean?
Living things
What does abiotic mean?
Non-living things
Where can pools of organic carbon be found?
In all living things
What does the ecosystem concept study?
Pools and fluxes of matter and energy
What are pools?
Quantities
What are fluxes?
Flows
What state are communities always in?
Flux
What is a community?
“The community is an assemblage of species populations that occur together in space and time”
What do ecosystems involve?
Communities and the physical environment
Define biodiversity?
“The variability among living organisms from all sources including, inter alia, terrestrial, marine and other aquatic ecosystems and the ecological complexes of which they are part; this includes diversity within species, between species and of ecosystems”
What is an issue with biodiversity definitions?
“… such definitions end up saying merely that biodiversity is equivalent to ‘all of biology’”
Why are there issues with the term ‘biodiversity’?
It is a relatively new term and has many meanings
How can there be diversity within species?
Genotypic and phenotypic variation
How can there be diversity between species?
Species diversity, equitability and disparity
How is there diversity within ecosystems?
Biomes, landscapes, ecosystems, habitats, niches
How does diversity vary?
With spatial scale
What is alpha diversity?
This is biodiversity within a habitat
What is beta diversity?
This is biodiversity between habitats
What is gamma diversity?
This is biodiversity in landscapes or between habitats in landscapes (landscape scale)
What is genotypic variation?
This is where there is a mutation in the genes between individuals of the same species or a different species
What is phenotypic variation?
Differences in observable characteristics
Define equitability
The extent of representation by equal numbers of individuals
Why would life be impossible without species interactions?
Organisms depend on one another for energy, nutrients and habitats
Why do actions in ecosystems have consequences?
Connections between organisms and the physical environment mean that events can have wide-ranging impacts
What is meant by the idea that ‘everything goes somewhere’?
There is no ‘away’ into which waste materials disappear
What does Commoner say is the first law of ecology?
Everything is related to everything else
Why does genotypic and phenotypic variation occur?
Due to genes and the environment
Explain why no population can increase its size forever?
There are limits to the growth and resource of every population
Explain what is meant by the concept ‘there is no free lunch’
The energy available to an organism is finite; increasing inputs into one function results in losses for other functions
What is meant by ecological carrying capacity?
The maximum sustainable population
Explain what is meant by maximum sustainable population
This is the maximum population that can be sustained for a long amount of time without an ecosystem crash
What is meant by the idea that species evolve?
Environmental change and competition for resources forces change in organisms
Why is time important?
Ecosystems change over multiple timescales; what has happened in the past shapes what we see now
What is important to look at when thinking about time?
Past and present conditions
What is meant by ‘ecosystem function’?
This is what an ecosystem does, it underpins ecosystem services
What are 6 functions that are part of ecosystems?
Photosynthesis Autotrophic respiration Decomposition Soil respiration Nutrient cycling Soil formation
What causes soil to accumulate?
Weathering
Why are ecosystem functions so important?
Humans can’t carry out the functions
What is the name of the bacteria that invented the process of photosynthesis?
Cyanobacteria
In which part of the plant does photosynthesis occur?
Chloroplasts
What do the chloroplasts contain?
Chlorophyll
What is the energy source for photosynthesis?
Light
What is the energy source for chemosynthesis?
Inorganic compounds
What is produced from primary production?
Complex C compounds from simple ingredients
What are two processes that can occur in primary production?
Photosynthesis
Chemosynthesis
Why is photosynthesis important?
It absorbs CO2
What is the photosynthesis equation? symbols
6 CO2 + 12 H2O = C6H12O6 + 6 H2O + 6 O2
What is the respiration equation? symbols
C6H12O6 + 6 H2O + 6 O2 = 6 CO2 + 12 H2O
What is the word equation for photosynthesis?
carbon dioxide + water = glucose + water + oxygen
What is the word equation for respiration?
glucose + water + oxygen = carbon dioxide + water
What happens in photosynthesis?
Carbon is reduced to form complex organic commpounds
What happens in respiration?
Carbon is oxidised to release energy
What is the equation for ecosystem function?
GPP-R=NPP
What is GPP?
Gross Primary Production
This is the total energy fixed
All the work that plants and bacteria do
What is R?
This is respiration (energy lost through metabolic processes)
What is NPP?
Net Primary Production
This is energy left over; often equated with biomass produced
Also crop yield
What is NPP a balance of?
Photosynthesis and respiration
Where is NPP highest?
In equatorial regions
What does terrestrial NPP account for?
Two thirds of global total
What is there a clear inequality in?
NPP
What percentage of NPP do tropical forests account for?
21.9
What percentage of NPP do tropical savannas account for?
14.9
What percentage of NPP do temperate forests account for?
8.1
What percentage of NPP do boreal forests account for?
2.6
What percentage of NPP does Arctic tundra account for?
0.5
Where is there considerable variation between in terms of NPP?
Variation between biomes
Why is there spatial variations in terestrial NPP?
Insolation
Moisture availability
Explain the spatial variation in marine NPP?
This pattern is quite different to that of terrestrial NPP
There is more NPP on continental fringes as there is lots of material from catchments
What is the pattern in marine NPP associated with?
Nutrient supply
What helps the nutrient supply?
Material from the catchment such as marine animals sink to the bottom and upwelling brings the nutrients up
How much of the total NPP do oceans account for?
1/3
What are autotrophs?
Primary producers
What are heterotrophs?
Primary, secondary and tertiary consumers
What do autotrophs do for energy?
They make their own
What do heterotrophs do for energy?
They rely on others
What do trophic levels show?
The feeding position of groups of organisms in an ecosystem
What are food webs?
Conceptual models of trophic interactions
Why are food webs complicated?
Because there is more than one food source
What is an issue with complicated food webs?
It makes it harder to predict the impacts if there is a species loss/introduction
Why is photosynthesis inefficient?
Not all light energy is utilised
Why isn’t all of the light used in photosynthesis?
The light hits the wrong part of the plant
The light is deflected
The light is the wrong wavelength
What happens between trophic levels?
Energy is lost
What is required to sustain top predators?
A huge quantity of NPP
On average, what percentage of energy in any trophic level is passed on to the next level?
10%
What is HANPP?
Human Appropriation of NPP
What percentage of the Earth’s bio-productive surface is dominated by people?
36%
What percentage of terrestrial NPP have humans appropriated?
40%
What is biogeochemical cycling?
The flows of chemical elements/compounds between living organisms and the physical environment
What is biogeochemical cycling important for?
The nutrient supply and human well-being
What is a major carbon pool?
The biosphere
What happens to atmospheric CO2 during photosynthesis?
It is drawn-down
What is a major player for the carbon cycle?
Humans
What do humans have a big impact on in terms of the carbon cycle?
Atmospheric CO2 however, there is more CO2 in biomass than in the atmosphere
Where is there a large reservoir of nitrogen?
There is a huge atmospheric reservoir of gaseous nitrogen (N2)
How is nitrogen fixed?
By microbes
What is meant by fixed nitrogen?
This means that it has been made into a nutrient for organisms
How can humans affect the nitrogen cycle?
They can increase the amount of fixed carbon
What is the P-cycle?
The phosphorus cycle
What type of nutrient is phosphorus?
It is a mineral nutrient
Macronutrient
What does the phosphorus cycle often limit?
Aquatic ecosystems
Where is most phosphorus derived from?
Rock weathering
What are most natural ecosystems deficient in?
Nitrogen
Where does disturbance occur?
In all ecosystems
Is nitrogen a limiting factor?
Yes
Is it normal to experience disturbance in an ecosystem?
Yes
Define ecosystem services?
“The suite of benefits that ecosystems provide to humanity”
What does disturbance interrupt?
It disrupts ecosystem functions and the delivery of ecosystem services
What keeps the system in equilibrium?
Feedback loops
What does the ecosystem tend towards?
An equilibrium state
By what type of feedback does self-regulation of ecosystems occur?
Negative feedbacks
Define stable situation
The ecosystem goes back to its original state after a minor perturbation
Define unstable situation
The ecosystem moves away from original state after a perturbation
What do stable ecosystems resist?
They resist being pushed away from the equilibrium
What is high engineering resilience?
This is a rapid return to original (equilibrium) state after a perturbation
What does engineering resilience assume?
A single equilibrium
What happens after an ecosystem reaches its threshold?
It goes into an alternative state, making it hard to get back to how it was
Define threshold
“The amount of disturbance that can be sustained before an ecosystem crosses an ecological threshold”
What does ecological resilience assume?
Multiple stable states
What is hysteresis?
Ecosystem state is determined by history and current conditions
Abrupt ecological change may be very hard to reverse
What percentage of the Earth’s land surface do cultivated systems cover?
25%
What percentage of land has been transformed or degraded?
39-50%
How much water is in reservoirs compared to natural rivers?
3-6 times as much water in reservoirs as in natural rivers
How much run-off water do humans use?
They use more than half of the runoff water that is fresh and reasonably accessible
How do humans disturb the water cycle?
Humans appropriate the majority of fresh, accessible water
Severe degradation of coastal ecosystems
By how much have atmospheric carbon concentrations increased since the pre-industrial era?
By 30%
Which two cycles do humans dominate?
N and P cycles with humans producing as much of these as all natural pathways combined
What are human activities increasing?
Extinction rates
What does loss of diversity impair?
Ecosystem function
What is the anthropocene?
This is a proposed geological epoch characterised by significant human impact on the Earth’s geology and ecosystems
What is the idea behind planetary boundaries?
There are global limits to exploitation
