3.5 energy and ecosystems Flashcards
explain energy levels in terms of trophic levels and energy loss
as energy passes through tropic levels energy is lost in terms of heat movement respiration etc
define decomposer
break down dead material to release nutrients
define saprobionts
micro organism that obtains nutrients from dead or decaying organisms
suggest why not all light hitting plant is absorbed
- wrong wavelength
- reflected
- transmitted straight through leaf
equation for gpp and npp
gpp - respiration = npp
what is gross primary productivity?
rate of production of chemical energy in organic molecules by photosynthesis in a given area given time KJ m-2 y-1
define succession
the process by which the structure of a biological community evolves over time
distinguish between primary and secondary succession
primary- in areas that has not been colonised
secondary- recolonisation of habitat following disturbance or damage
define climax community
stable community that has reached equilibrium with its environment- no further change occurs
stages of succession(6 steps):
PIONEER species- first organisms to colonise
as something develops it OUTCOMPETES
more and more outcompetes eventually leading to climax community
1) weathering creates small cracks in the rocks
2) mosses and lichens begin to colonise, organic matter builds up slowly
3) Legumes begin to grow as they are able to fix atmospheric nitrogen to supplement the poor nutrient soil. As they die, soil becomes enriched.
4) Grasses and ferns start to grow, sheltering the soil from the elements.
Soil, and its moisture content increases.
5) Large shrubs and small trees colonise. Leaf litter greatly increases fertility and humus content of the soil.
Habitats created for nesting birds and soil invertebrates so diversity increases
6) Climax woodland is reached.
define niche
organisms role within an ecosystem
why is a transect more appropriate than random sampling
transect is sampling along changing conditions and random doesn’t show distribution
