Lectures 3-4: Conditions and resources

Question 1

what are conditions?

Answer 1

> 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

Question 2

describe the normal curve of performance of species as intensity of condition increases

Answer 2

> 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

Question 3

describe a poison curve

Answer 3

> 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

Question 4

describe the NaCl performance curve

Answer 4

> 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.

Question 5

what are resources?

Answer 5

> 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

Question 6

how do conditions and resources vary?

Answer 6

> 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

Question 7

what are the effects of conditions ? specifically temperature?

Answer 7

> 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

Question 8

what is the temerature size final rule?

Answer 8

> 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

Question 9

what is the effect of interactions between organisms?

Answer 9

> 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

Question 10

what resources do primary producers need?

Answer 10

> green plants are the primary producers
> they need:
 - radiant soler energy (heat and light)
 - atmospheric CO2
 - minerals (from soil)
 - H2O

Question 11

what are the resources in a mixed conifer-deciduous forest?

Answer 11

> 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

Question 12

what is the leaf area index?

Answer 12

= total leaf area / projected ground area

Question 13

what are the resource (PAR) breakdown in a meadow?

Answer 13

> 20% reflected by top of canopy
> 5% tops of grasses
> 36% lower parts of plants
> 34% grasses
>5% earth

Question 14

How does light change in the water column?

Answer 14

> attenuation of quantity of light and changes in spectral distribution in a water column

Question 15

how does PAR vary?

Answer 15

> 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

Question 16

what is the absorption of PAR in terrestrial plant canopies?

Answer 16

> 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

Question 17

describe conservation and acquisition of water by terrestrial plants?

Answer 17

> 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

Question 18

describe the different root systems of plants thate help with water aquisition.

Answer 18

> 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.

Question 19

describe CO2 as a resource

Answer 19

> 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

Question 20

what are the three geographic patterns?

Answer 20

> solar radiation
ocean currents
land topography - local topography affects local conditions

Question 21

describe solar radiation

Answer 21

> 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

Question 22

describe ocean currents

Answer 22

> SH: currents anti clockwise

>NH: currents clockwise

Question 23

Describe global temperature variation

Answer 23

> 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

Question 24

what are biomes?

Answer 24

> 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

Question 25

what are the current and predicted effects of human activity on biomes

Answer 25

> change the distribution of biomes around the world

>

Question 26

how do biomes vary?

Answer 26

> local variation and gradients
local topography and geology and soil
decrease in temp, decrease in rainfall up a vertical gradient = different biomes up that gradient

Question 27

describe temporal patterns in conditions and resources: plant successsion

Answer 27

> after a lava flow event has occurred and wiped out vegetation

1) colonisation by alnus, which is good at fixing atmospheric N to improve the soil quality
2) facilitation by N fixation of Alnus, colonisation of Prunus and Machlius - can only colonise because of Alnus
3) disappearance of Alnus and Prunus colonisation of Castanopsis - shades out the other species, so thats why only this species exists

Question 28

describe and classify biomes

Answer 28

> different biogeographers recognise different numbers of biomes
biomes: area of land dominated by plants with characteristic shapes, forms and physiological processes
NOT a map of distribution of species
groupings of plants of similar species

Question 29

describe the tropical rainforest biome

Answer 29

> global peak of biodiversity
most productive biome
- high solar radiation
- reliable rainfall
production achieved high in dense canopy
intense soil activity
- rapid decomposition of leaf litter (soil surface almost bare)
- most nutrients in plants themselves ( lost when cleared); poor regeneration
high animal diversity:
- reliable food sources for specialists
- high floral diversity and parallel specialised diversity of pollinating insects and birds

Question 30

describe the Savannan biome

Answer 30

> seasonal rainfall restricts plant and animal diversity
plant growth limited for part of the year by drought: seasonal gluts and shortages of food
migration of large animals and birds
temp constant
rainfall varies a lot
when temp exceeds rainfall, not suitable for plant growth
- this happens in june or july
grasslands and scattered trees that typically would be forested but are prevented by either:
- grazing herbivores - grass adapted to grow after being eaten, can persist in environment
- unfavourable conditions - waterlogging, drought, poor soils
- fire - adapted to grow afterwards

Question 31

describe hot deserts

Answer 31

> at most extreme, too arid for any vegetation
desert plants adopt one of two strategies:
- rapid growth, set seed in weeks, seeds lay dormant till next rain
- cacti and succulents: thick fleshy stems, small thick, hairy leaves, long periods of physiological inactivity, conserve water
graph says conditions are never favourable for growing because no to little rainfall.
animal diversity is corresponding low

Question 32

describe temperate grasslands

Answer 32

> warm moist summer and cold dry winters
fire and frequent grazing
e.g., bison and grasshoppers, invertebrate biomass can be > large vertebrate biomass
soils rich in organic matter; well suited to agriculture
temperate grasslands more affected by man than any other biome - exploited for farming

Question 33

describe temperate shrubland and woodlands

Answer 33

> characteristic of Mediterranean climate
asynchrony between favourable growth temperatures ( summer) and available water (winter)
regular fire prevents succession to woodlands ( plants have subterranean storage organs or seeds that germinate rapidly after fire
spain
WA and SA
difficult for plants to manage

Question 34

describe temperature deciduous forests

Answer 34

> deciduous leaves adaptation to long periods of freezing
fertile soils allow replacement of leaves annually
vertical structure: tall trees, shrubs and forbs; diverse but less so than tropical rainforests
fire and large scale insect outbreaks NOT characteristic
fertile soils: vast areas all continents cleared for agriculture
Europe, eastern USA and China
favourable for growth in summer, loss of leaves in winter

Question 35

describe temperature evergreen forests

Answer 35

> occur over a wide range of rainfall
nutrient poor soils ( affected by pH of leaves)
fire can promote persistence
reduced diversity compared with deciduous counterparts
high quality timber and pulp-extensive logging

Question 36

describe boreal forests

Answer 36

> high latitudes in northern hemisphere
characterised by permafrost ( frozen sub-surface of soil for 3 years)
soils wet with high C content (important in C cycle- climate change may result in melting of permafrost and release of C into atmosphere)
fires started in dry summers can burn for years
trees: conifers, larch, birch, aspen; give way to huge tracts of spruce ( low biodiversity)
largest biome by area 1/3 of forested land
climate change is moving them further and further north

Question 37

describe the tundra biome

Answer 37

> extremely high latitudes in northern hemisphere (>65 degrees)
> characterised by permafrost
> shrubs, grasses and sedges
> not diverse
> 3 months not below freezing

Question 38

what are the characteristics of water?

Answer 38

> dipolar structure dissolves and holds mineral ions required for plant growth
O2 solubility decreases rapidly with increasing temperature, O2 diffuses slowly in water
viscous: transports small animals and plants; resistance to movement of larger animals and larger plants need firm contact with substratum
remains liquid over a wide range of temperatures and has a high specific heat capacity; large bodies of water vary little in temperature over the seasons

Question 39

describe the ocean biome

Answer 39

> oceans cover major part of earth’s surface
single cell algae responsible for most photosynthesis
- very efficient
- limited by access to required nutrients
tropical oceanic production tropical terrestrial production >800g C m^2/year