Lectures 3-4: Conditions and resources Flashcards
what are conditions?
> physicochemical features of the environment, e.g.
- temperature
- humidity
- pH
altered in the immediate environment of an organisms ( humidity around a tree)
not consumed/ used up by an organism
describe the normal curve of performance of species as intensity of condition increases
> survival over a wide range > growth over a more restricted range > reproduction even more restricted > biochemical reactions double in rate at 10 degree celsius increase > breaks down at higher temperatures > refer to graph
describe a poison curve
> refer to diagram
at low levels, no effect on performance
as levels increase, still no effect
reaches a precipitous drop, starts to effect reproduction, then growth, then survival
describe the NaCl performance curve
> refer to diagram
at no levels of salt, no survival, reproduction or growth,
then at some level of salt, RGS intact, then at too high levels, RGS effected.
what are resources?
> consumed by organisms in course of maintenance/ growth/ reproduction
- photosynthesis uses solar radiation, CO2, H2O, minerals
- herbivores consume plants, carnivores consume animals
- consumption of resources leaves less available for other organisms
how do conditions and resources vary?
> solar radiation (heat and light) varies seasonally
- less radiation per unit area in N+S
- tilted axis = seasons
temperature varies seasonally and with latitude
- temps on land lower than sea
- less land mass in SH
- local temp varies altitude
- local temperature varies with depth and season in water bodies
what are the effects of conditions ? specifically temperature?
> linear relationship between temperature and growth and development in protists and mites
development frequently increases more rapidly than growth with increasing temperature,
- higher temps = smaller individuals
- colder temperatures = larger individuals
what is the temerature size final rule?
> final size tends to decrease with rearing temperature
general implications:
- geographical size variation
- seasonal size variation
- seasonal variation in fecundity
- interactions between organisms in a changing climate affected
what is the effect of interactions between organisms?
> different organisms may respond to changes in temperature
fungus grasshopper relationship
- fungus growth = declines above 25 degrees and inhibited at 35 degrees
infected grasshopper will ‘bask’ in the sun to increase body temp and ‘cure’ the disease by killing the fungus
what resources do primary producers need?
> green plants are the primary producers > they need: - radiant soler energy (heat and light) - atmospheric CO2 - minerals (from soil) - H2O
what are the resources in a mixed conifer-deciduous forest?
> absorption and reflection of photosynthetically active radiation (PAR) > 79% absorbed by upper canopy > 10% reflected by top of canopy > 7% lower parts of larger trees > 2% shrubs > 2% ground plants
what is the leaf area index?
= total leaf area / projected ground area
what are the resource (PAR) breakdown in a meadow?
> 20% reflected by top of canopy > 5% tops of grasses > 36% lower parts of plants > 34% grasses >5% earth
How does light change in the water column?
> attenuation of quantity of light and changes in spectral distribution in a water column
how does PAR vary?
> seasonal and diurnal variation in availability of PAR terrestrial plant canopies
in winter, plants lose leaves to cope with less PAR as leaves are the area of the plant that need it.
in summer when there is more PAR available, the plants grows many leaves to take full advantage of this
also, in spring, when leaves grow back, newer smaller plants can grow because they are not being shaded by the canopy, so they have access to PAR
what is the absorption of PAR in terrestrial plant canopies?
> rate of photosynthesis varies with radiation intensity and plant species
excessive radiation can reduce rate of photosynthesis
the angle of leaf affects quantity of radiation absorbed
leaves in a canopy ( and near ground) receive intermittent radiation when the leaves are tilted, allowing for more sunlight to break through the canopy
describe conservation and acquisition of water by terrestrial plants?
> plants can only absorb CO2 for photosynthesis across wet surfaces. a balance needs to be struck between CO2 acquisition and water loss
adaptations of deciduous and evergreen tree species in Australian tropical savana.
canopy fullness = number of leaves
predawn water potential = water stress
refer to graphs
describe the different root systems of plants thate help with water aquisition.
> root systems
- depend on plant strategy to deal with water scarcity and local conditions
- germinating conditions effect root systems, i.e., rainy = less roots, shallower
annual grass - large thick, semi deep roots
annual weed - shallower roots, thick but not as dense as annual grass
ephemeral weeds - basically no root system at all, very tiny and shallow, do not invest energy in roots, during droughts they are seeds
desert shrubs - very, very deep roots, not that dense, just very long.
describe CO2 as a resource
> CO2 variation in space and time (mixed deciduous woodland)
in winter, the CO2 conc. is the same across all canopy heights, but in summer it varies tremendously
refer to diagram
elevated CO2 can increase plant growth
elevated CO2 tends to decrease N concentrations in plant tissues, leads to increased food consumption by herbivores to maintain N intake
complex
what are the three geographic patterns?
> solar radiation
ocean currents
land topography - local topography affects local conditions
describe solar radiation
> global energy balance
- drives the climate system
if greenhouse gases weren’t around the earth would be 30% cooler
earth isnt cooling as quickly as it should because it the solar radiation is being reflected by greenhouse gases
there is more rainfall in tropical area
due to hadley cells either side of the equator
fernell cell = hot and cold air
high pressures = desert conditions
polar cells
describe ocean currents
> SH: currents anti clockwise
>NH: currents clockwise
Describe global temperature variation
> greater temp variation on land versus sea
distribution of animal on land and dealing with differing temps
differences in annual precipitation = more around the equator
what are biomes?
> large scale biological communities shaped by the regional climate, soil and disturbance patterns
usually classified by the growth form of dominant plants
no fixed biomes, how you define it
