Lecture 9- Coping with aridity and drought III Flashcards
(16 cards)
What structure allows Cactoblastis cactorum to find the prickly pear?
labial palsp located in either side of the proboscis can measure CO2 with a resolution of 1ppm
-that is how cactoblastus found the opuntias
Can Cactoblastis cactorum be a problem?
• Cactoblastis introduced to South Africa, Hawaii, Bahamas
• Moved from Bahamas to Florida
• Advancing across SE USA and Mexico
-cactoblastis may be a problem for where prockly pear occurs naturallly
What are the basic principles of how to survive in a desert?
• Stay wet • Stay cool • Tolerate dehydration • Tolerate over-heating
- water is the key to survival, have to stay wet and cool
- helps to tolerate dehydration and over-heating
Why is water important for organisms in the desert?
- Good solvent at physiological temperatures
- Maintain structure (turgor) • Cooling (latent heat loss) • Transport • Price of fixing CO2
- Substrate for photosynthesis
- High temperatures can lead to irreversible damage
Do plants sweat?
- yes
- transpiration
- latent heat loss as it takes lot of energy with it
- 99% of water that gets into a plant is evaporated
- only a little bit is used in photosynthesis
Is there a connection between rainfall levels and plant productivity?
productivity of plants is highly correlated with amount of rainfall
- the ability to make dry matter= grow
- this is globally
- hyperbolic relationship
Where do you get radiation from when outside?
- you will pick up radiation when you are outside= comes from the sun (solar) and from the surroundings (from absolute heat, everything above absolute zero emit it)
- net radiation load= the total amount of the two
What is the net radiation load?
the sum of solar heat and heat from the surroundings
What is sensible heat loss?
- e.g. from warmer leaf to cooler air
- as you get hot and rise above the air temperature= that heat is transferred to the surrounding, both inanimate and animate objects heat up and trasfer it to the air
What is latent heat loss?
-via evaporation of water, takes lot of energy from the organism
What does survival in the desert and elsewhere depend on?
- involves manipulation of load and/or disipation/loss processes
- go to the shade or something like that
What is the sauna experiment?
• Set sauna at 110 C • Sit still and appraise
fluxes • Large sensible heat gain • Large latent heat loss
• Boundary layer reduces sensible flux
-hotter than you so get sensible heat gain
-sweat= latent heat loss
-boundary layer= aerodynamic boundary layer= boundary of still air that imposes a resistance to sensible heat gain
-that is why it is good not to move
What is a boundary layer and how is it important in maintaining temperature?
- boundary layer= aerodynamic boundary layer= boundary of still air that imposes a resistance to sensible heat gain
- that is why it is good not to move
What balance maintains body temperature within set physiological range
-the balance: the sensible and latent heat maintain body temperature in physiological range
What are the strategies of avoiding heat in kangaroos?
survival strategy 1: reduce radiation load
- kangaroos licking their forearms= veins close to surface, lick and latent heat loss= cool down
- dig the soil so can get to the cooler ground underneath
- wet areas have lower sensible heat flux
- hide in the shade as well
- solar radioation(shade), latent heat(licking) and sensible heat(ground)= have to balance
What are the factors on a plant that can be manipulated to deal with temperature change?
! Leaf orientation ! Leaf shape ! Leaf amount ! Leaf optic
