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
Physical damage from wind
windthrow
abrasion by windborne particles
“flagging” shape in woody plants (lost branches on one side)
desiccation by dry winds
Adaptations to wind
dwarfing/cushion growth forms
hairy leaf surfaces or thick waxy cuticle to protect more sensitive parts from flying particles
Ionic toxicity
Injury from osmotic effect or direct toxic effect of ions caused by salts
Example of plant with salinity resistance
Salt cedar (salt accumulates in foliar gland and then are deposited on soil surface)
A plant adapted to salinity is often also adapted to _________
drought
Common source of acute short term toxicity
acid deposition from fossil fuel combustian
What does acute short term toxiticy cause?
direct injury to leaf surface
acidified soils
aluminum toxicity (acid rain)
loss of important cations
Ecological impacts of toxicity
chronic/long-term toxin exposure can lead to adaptation
serpentine soils lack nutrients and often have high nickle, cobalt, and chromium concentrations
diverse endemic flora
trade off
whn increasing performance of one feature, organism must decrease another
Examples of important tradeoffs
annual vs perenial
evergreen vs deciduous
growth rate vs defense
seed size vsseed dispersial
seed size vs seed number
Functional types (strategies)
gymnosperms
angiosperms
dicots
monocots
Life history
organism’s lifetime pattern of growth, development, and reproduction
common history life patterns recognized as functional types
Functional groups
graminoids
forbs
shrubs
trees
vines
nitrogen fixers
Graminoids
grasses and grasslike plants
monocots with extensive fiberous root systems
imprecise foragers
renew above-ground biomass annually
Forbs
Herbaceous dicots with fibrous and/or taproots with 2 common growth forms prostrate/rosette and erect
Prostrate/rosette
grows close to ground and only grows up when it is going to flower
Erect
shoots up in stem, is tall, and has lots of leaves coming off stem
Shrubs
Plants that accumulate above-ground woody tissue and is typically around 4.5m tall
trees
tall woody plants that are better at competing for light than shrubs but require more resource avability. Typically taller than 4.5m
vines
often woody climbing plants that are unable to support themselves due to thin stems
Nitrogen fixers
fix nitrogen through rhizobia or other bacterial associations and can exhibit multiple forms
competitive CSR classification
Need high nutrient levels
fast growing
utilize resource avalibility
stress tolerant CSR classification
slow growing to avoid nutrient loss
can tolerate low nutrients and harsh environments
maximize traits to maintain structure (not to grow quick)
ruderal CSR classification
fast growing but not competitive
finish life cycle fast
rapidly colonize sites
maximize seed output
often annual weeds
How does the CSR triangle seperate plants?
along gradient of competitive intensity, environmental stress, and disturbance frequency/intensity
what drives roots vs shoots allocations?
relative requirements for soil resources and light
why is total root biomass so much higher in grasslands?
More perenial species, so they have more time to accumulate roots
Fast-slow economic spectrum in leaves
Invest more in leaves and they will be more efficent/last longer, but u will grow slower
Invest minimally in your leaves and you can grow fast, but leaves will be more suseptible to damage and resource leaking
Height trade off
taller plants are better at capturing light, but more suseptable to damage
seed trade off
bigger seeds allow better establishment, but dont disperse as far
