module 5 Flashcards
what is ecosystem ecology?
studies the link between organisms and their physical environment within an each system context
what are ecosystem processes?
the transfers of energy and materials from one pool to another.
what is a pool?
the different compartments or reservoirs within an ecosystem.
what is a stock?
the quantity of material held in a pool.
measured in units of mass per unit area.
state factors
influence ecosystem processes but they are external to the ecosystem (e.g. climate and topography)
interactive controls
both control and respond to ecosystem properties (e.g. resources and disturbance regime)
carbon cycle is relatively (…..) - inputs and outputs to the ecosystem are (…..)
- open
- large
phosphorous cycle is relatively (…..) - inputs and outputs to the ecosystem are (…..)
- closed
- small
gross primary production
photosynthesis at the scale of the ecosystem.
how is carbon lost to the environment?
- respiration by plants and animals
- combustion (burning)
net primary productivity (NPP)
the carbon a plant has left to allocate to growth after losses trough respiration.
net ecosystem productivity
NPP - respiration
(how much carbon accumulates in the ecosystem)
what % imbalance of carbon is there globally?
6%
what are the two main direct controls on GPP?
leaf area (area for light capture)
growing season length (time for light capture)
dominance hypothesis or ‘mass ratio effects’
the effect of each species is additive, and proportional to it’s abundance. the dominant species have the most impact
nich complementary hypothesis
the presence of a diversity of species traits, is important in determining ecosystem processes
heterotrophs
organisms that rely on external sources of organic material for energy and growth
autotrophs
organisms that make their own food.
saprotrophs
heterotrophs that feed on detritus (dead things)
decomposition
chemical and physical breakdown of detritus which ultimately releases CO2 to the atmosphere, as well as inorganic nutrients
detritivores
consume detritus and chemically alter the material inside their bodies
decomposers
produce enzymes that degrade detritus or soil organic matter outside the cell
microflora and microfauna responsible for decomposition
Nematoda
fungi
protozoa
rotifera
mesofauna responsible for decomposition
acari
collembola
labile
simple chemical constituents - easier to break down
recalcitrant
larger more complex molecules - harder to break down
arbuscular mycorrhiza (AM)
fungi form within root cortical cells
not decomposers
ericoid mycorrhiza (ERM)
fungi form within root epidermal cells. single hypha
heathland ecosystems
ectomycorrhiza (ECM)
fungi form in between root cells.
large hyphae network. can also form rhizomorphs (fungal cords)
woody species
what is a useful way of measuring activity of decomposition?
measuring CO2 production.
how does temperature impact decomposition rates
heat soil up - it will produce more CO2.
heat it up - moisture content of soil changes and influences decomposition rate.
how does substrate quality and quantity impact decomposition rate.
litter with lots of labile constituents will decompose faster
stoichiometric constraints
the carbon to nitrogen ratio in plants is the best predictor of how fast it will decompose.
what ratio do these decomposers need to grow and are they available? = stoichiometric constraints
home field advantage
things will decompose more quickly in their home environment because the microbial community is better adapted to decomposing that kind of litter.
rhizosphere priming
plants growing in the soil can impact the microbial community activity and thus the rate of decomposition.
predator
any organism that consumes all or part of another organism - benefitting itself.
what are the 4 types of predators?
true predators - kill and eat the whole prey
grazers - consume only part of the organism
parasites - consume only part but live on or in the host.
parasitoids - lay eggs in or on the host.
two types of parasites
MACROPARASITES - grow but do not replicate in/on the host
MICROPARASITES - replicate inside the host
what is a pest
insect or small animal that causes destruction.
usually herbivores.
how does defence come as a cost?
energy used on defence cannot be used on growth and reproduction.
how does outbreak of autumnal and winter moth cause defoliation in forest canopy?
pupae in soil, females emerge and lay their eggs on the tree trunk.
caterpillars that emerge from these eggs eat the leaves in the summer time.
top down control in forests.
app is being impacted by species at a higher trophic level.
how do trees recover after being attacked by moths?
when moths dies they produce a pulse of nutrients available for the tree to grow.
what does a mountain pine beetle do to pine trees?
first beetle to arrive at a pine tree releases pheromones for many more beetles to arrive.
they bore into the tree and break the phloem connection between the roots and leaves.
no photosynthetic transport to root. no root uptake = tissue death - tree dies.
