Obtaining Essential Resources Flashcards
Important developmental cues
Germination shoot elongation
Orientation
Flower initiation
Photosynthesis
Capture of energy from light uses to convert CO2 to physiologically useful carbon compounds
Positive net photosynthesis
When plants have enough light and can successfully photosyntesize (some plants have higher or lower saturation)
Photosythetically active radiation
Wavelengths between 350 and 700nm. Driven by the absorbance spectrum of chlorophyll and other photosynthetic pigments
Light competition
Intercept light before your neighbor does
What size plants intercepts more light?
Bigger plants
Light competition is ____________
asymmetric (plant only has to be a little taller
Competitive strategies for light competition
taller plants
growing faster
bigger leaves
low investment in leaf structure
low light tolerance
avoidance of shading
Tolerating low light strategies
shade adapted leaves
specialization on shorter wavelengths that can penetrate the canopy
changes in leaf structure to take advantage of light from different direction
Examples of shading avoidance
Wild leeks/ramps, downy yellow violet, heart-leaved foamflower
Carbon dioxide
rare component of atmosphere (below 0.035%, 408ppm and rising 2-3ppm per year)
What happens when there is too little CO2?
plant will fix O2 instead (photorespiration), which reduces photosynthesis 30-50%. Not really useful to plant
Transpiration
Movement of water from soil through plant vascular system and out stomata
Opening stomate to obtain CO2 _______ the plant water
costs
Why do plants close stomata during hottest part of day?
to reduce water loss
C3
- Most common photosynthetic pathway
- stomata open during sunny parts of the day making plant dependent on abundant transpiration water
C4
- Carbon storage and internal transfer
- carbon concentration mechanisms to avoid photosynthesis
CAM
- Crassulacean acid metabolism
- CO2 captured at night, stored as malic acid
C3 ideal climate
cooler, wetter climates
C4 ideal climates
warmer, dryer climates
Belowground resources
Water, micronutrients, macronutrients
What do macronutrients limit?
plant growth and productivity
What do micronutrients limit?
limit growth of certain species depending on requirements
Water avalibility depends on….
supply and infiltration
Root stratagies for obtaining water
root deeply or high root density
Plants can tolerate drier conditions if they can retain ______ water
more
Plants can access more water if they root _____ deeply
more
nutrient uptake is _______ in dry conditions
limited
Nutrient uptake depends on
how much is availible
frequency of deposition
Traits associated with nutrient uptake
root system architecture
root foraging precision
nutrient uptake kinetics
interactions with microbes
Essential macronutrients
Nitrogen, phosphorous, potassium, calcuim, magnesium, sulfur
Essential micronutrients
chlorine, iron, manganese, boron, zinc, copper, mickel
Nutrients generally have a ______ _________ in the soil
patchy distribution
How do nutrients get to the roots?
Diffusion and mass flow
Diffusion
- Slow
- Along a concentration gradient where root needs to be very close to take stuff up
- Important for P, Mg, Ca, and most micronutrients
Advantages of intensive root use
Fast
Effective for capturing ephemeral (short time) resources
no need to spend energy of building new roots
Disadvantages of intensive root use
Plants have to have roots in the right place (cannot reach new patches)
cannot displace competitors
Advantages of selective root growth and death
live roots use energy, so energy is saved by eliminating less productive ones
adjusting time of death
can take some nutrients back from roots
Disadvantages of selective root growth and death
slow relative to physiological adjustment
loss in investment when roots turnover
Root proliferations
rapid production of new roots in nutrient rich patches
Precise foraging
requires less upkeep because roots are only placed where they are useful
allows plants to take advantage of unpredictable and spatially heterogenous resources
Imprecise foraging
Allows plant to intercept resources, but has a greater upkeep cost
roots need to be in right place to find the resources in the first place
Root competition
symmetric because bigger plants dont have an advantage
