Environmental Constraints: Water, Temperature, Wind, Salt, And Toxins Flashcards
Examples of abiotic stress factors
temperatures, water, radiation, chemical stress, mechanical stress
Drought avoidance
desert annuals complete life cycle rapidly after rain (live fast die young)
Drought deciduous
lose leaves during dry season, typically expansive belowground
Drougt tolerant adaptations
Invest heavily in root systems
more but smaller stomata
thick and tough leaves
enter domat state during drought
increase solutes to increase osmotic potential
Flooding adaptations
switch to glycolysis to avoid oxygen requirements during ATP synthesis
roots may have aerenhyma (hollow chambers that allow oxygen to flow through plants
Temperature classifications for plants
Chilling sensitive
Freezing sensitive
Freezing tolerant
Chilling sensitive
injury below 10-15 C. Change in membrane stucture inhibits cellular function
Freezing sensitive
Injury below 0 C. Creation of ice crystals cause physical damage to cells
Freezing tolerant
supercooling prevents cellular contents from freezing up to a point
What determines distribution of species (temp)
Huge variation in temperature as a function of latitude and altitude
Dwarfing
Decreased investment in vunerable woody areas, causing plant to grow closer to the ground
Leaf adaptations to cold temperatures
thicker, tougher leaves
waxy coating to reduce water loss
reduction in photosynthesis
Acclimation response to cool temps
change in fatty acid membrane to increase chilling resistance
change chemical compensation in leaves to avoid freezing
enter dormant state with senescence of leaves
dominant type of trees in lack of freezing lands
broad evergreen leaves
dominant type of trees in freezing winters
deciduous broad-leaved species
dominant type of trees in freezing temps with short growing season
evergreen coniferdominance
Primary effect of heat on photosynthesis
effeciency of photosynthesis declines above 25 C or C3 plants (slows)
How is heat injury tied with water limitation?
temp greater than 40 C cause plants to cease transpiration cooling to conserve water
How do plants cool down?
Transpiration cooling
long wave radiation emission
convective cooling
heliotrophic sun tracking
life history strategies to avoid hottest part of year