6.3.1 ecosystems Flashcards
(43 cards)
population
all the members of a single species living in an area
community
all the populations of different species which intera t together in the same habitat
ecosystems
the interactions of the living (biotic) and a biotic factors in an environment
1st step of food chain
producer
- synthesise their own organic molecules using light energy from the sun
after producers are
primary consumers
how does interdependence arise
- food chains are all connected as food webs
- as pop of one species increases, that of another increases who eats it, and that of its prey decreases
decomposers
break down dead naterial and allow nutrients to be recycled
how is energy lost between trophic levels
- egestion
- not all of an organism is eaten
- faeces
- heat loss in respiration
efficiency of biomass transfer
(biomass transferred/ biomass intake) * 100
how to measure biomass
- choose the SAME one area u want to sample
- take a sample of both trophic levels
- dry orgs in an ocen until constant mass
- calroimetry to work out kj
- scale up fpr total area , kj/m2/year
- efficiency = tropic level2 energy/trophiv level1 energy * 100
LIMIT: assumes everyone only eats one organism , inaccurate
net productivity
the amount of biomass availabel to next trophic level
gross productivity and units
total energy consumed by organism (kj per m2 per year)
how to calc net productivity
gross productivity - respiratory loss
efficienc of energy transfer
net/total * 100
how can farmers maximise efficeincy
ANIMALS
1. keep animals in small cages to restrict movement -> less energy lost in resp so more for biomass, higher gross production
2. keep warm
2. antibiotics to prevent energy needed to kill infections
3. selective breeding
PLANTS
3. herbicides to reduce competition
4. insecticides
5. fungicides (less energy required to kill fungal infections)
carbon cycle steps
- co2 to atmosphere => respiration and combustino of fossil fuels
- co2 out of atmosphere =>photosynthesis
- aninals feed on plants
- when plants and animals die, decomposers break down their material and RESPIRE, RELEASING CO2
- In ABSENCE OF DECOMPOSERS (no o2), carbon compounds form fossil fuels (high t and p over millions of years)
nitrogen cycle descriibe
- rhizobium in root nodules, azobacter in soil, lightning do NITROGEN FIXING, n2 in atmosphere to AMMONIA/nh4 +
NITRIFICATION
2.nitrifying bacteria (nitrosomonas) convert nh4+ to no2-
3.nitrobacter do no2- to no3-
4.no3- active transported (taken in ) by plants for eg dna
5.denitrifying bacteira do no3- back to atmospheric n2 (usually in anaerobi)
6.death and decomposition, decomposers do ammonification of dead stuff to nh4+
succession
progressive change in an ecological tommunity over time
describe succession
seral stages
1. PIONEER species eg algae lichen live on bare rock. they may have advantageous adaptations eg can fix n2, can photosynthesise, produce large vol of seeds and spores which can be wind carries. biomass is LOW
2. PS die and decompose, forming a basic soil called humus. soil ph and salinity and nutrient content changes, becomes deeper and thicker
3. INTERMEDIATE SPECIES larger simple plants eg shrubs can grow => biodiversity increases
4. may block light from lower down plants, so they die and decompose, soil content changes
5. eventually u have the largest species, climax community, DOMINANCE by a few large trees, no more succession
deflected suvvession
CLIMAX COMMUNITY PREVENTED FROM DEVELOPING
- grazing
- fertiliser
- herbicide
- the community that results is a plagioclimax
how to sample (quadrats)
- set down 2 tape measures ppd to each other
- RNG to generate coordinates
- place quadrats at coords
- estimate eg % cover
- more quadrats = more respresentative
stratified sampling
- number of samples proportional to area
transect used when u wann asee
how the distribution of different species changes along a habitat
line transect
tape measure placed along a line, any species that touch tape masure are recorded
