Ecosystems, Lecture 35 Flashcards
To grow, plants need:
3
- energy from the sun
- water and nutrients from the soil
- other nutrients from the atmosphere
The network of relationships between plants and animals extends to processes…
operating in the soil and in the atmosphere
Ecosystem concept
3 aspects
- organisms and the environment
- applies at any scale
- energy flows and nutrient cycles are fundamental features
Ecosystem inputs
5
- solar radiation
- precipitation
- rock weathering
- organisms
- humans
Solar radiation
as an ecosystem input
powers all ecosystem processes
Precipitation
as an ecosystem input
supplies water and nutrients
Rock weathering
as an ecosystem input
inputs of nutrients to soil
Organisms
as an ecosystem input
can enter from outside eg: migrating animals, windblown seeds
Humans
as an ecosystem input
plant seeds, introduce animals, use fertilisers and pesticides to control organism growth
Ecosystem outputs
- water
- thermal radiation/heat
- plant and animal material
- leaf litter
- animals
Water
as an ecosystem output
May drain through soil and flow out of the area in a stream
Thermal radiation/heat
as an ecosystem output
can escape back into the atmosphere
Leaf litter
as an ecosystem output
can be blown into another area by wind
Animals
as an ecosystem output
migrate away
Plant and animal material
(as an ecosystem output)c
can be removed by humans
Are ecosystems closed or open systems?
Are flow and cycles closed or open systems?
ecosystems = open systems
some flows and cycles in them = closed systems
Changing one component of an ecosystem can lead to…
changes in all other components
A food chain illustrates
2
- links between organisms by the transfer of energy
- how each organism tends to fulfil a specific role within the ecosystem and how each organism maintains specific relationships with other organisms
Two groups of organisms
- autotrophs
2. heterotrophs
Autotrophs (producers)
manufacture own food using solar energy, carbon dioxde, water and nutrients
Heterotrophs (consumers)
3 types
primary and secondary consumers
decomposers
Type of heterotrophs
primary consumers
herbivores,
eat autotrophs
Type of heterotrophs
secondary consumers
carnivores,
eat other heterotrophs
Type of heterotrophs
decomposers
decompose dead tissues of other organisms
Why are food webs better than food chains?
shows the many possible routes which energy can take
How does energy flow through ecosystems?
passes from one trophic level to another
First trophic level
producers
Efficiency of transfers between trophic levels
not very efficient, considerable energy losses during each transfer
What is most of the energy loss between trophic levels due to?
loss of heat
In most cases, outputs of heat energy more or less equal…
inputs of solar energy
All energy that enters an ecosystem…
eventually leaves
Photosynthesis equation
6H2O + 6CO2 + solar radiation -> C6H12O6 + 6O2
By-product of photosynthsis
oxygen
Which type of organism carries out photosynthesis?
autotrophs, convert solar energy into chemical energy
Respiration equation
C6H12O6 + 6O2 -> 6H2O + 6CO2 + energy
Respiration
Heterotrophs released stored chemical energy
Energy is used to…
2
produce compounds needed for growth (tissues)
do some form of work (eg: movement)
Percentage of total energy passed on to next trophic level
<10%
Trophic pyramid
eg: number of herbivores is lower than the number of plants that support them
Maximum number of trophic levels generally and why?
five,
because only a fraction of energy is passed between trophic levels
Main five important nutrients
carbon, oxygen, nitrogen, phosphorus, potassium
Three examples of inputs of nutrients into ecosystems
- rock weathering
- rainfall
- from the atmosphere
Two main routes nutrients can pass through the ecosystem
grazing and decomposers/detritus systems
Nutrient molecules can …
be used over and over again by organisms
