Chapter 4: Forest Ecophysiology Flashcards
What two disciplines does ecophysiology combine?
Physiology and ecology
What is the main focus of ecophysiology?
Whole-organism function
What does ecophysiology address evolutionarily?
Adaptations to specific environments
What are six areas of focus in ecophysiology?
Thermoregulation, energetics, nutrition, gas exchange, water/osmotic balance, stress responses
What are two ways that ecophysiology extends beyond organism level?
By modeling ecosystem behavior and predicting human impacts
What are three examples of elements of tree anatomy?
Structure/function of leaves, stems, roots
What are two examples of elements of tree physiology?
Seasonal responses and stress/resource availability responses
Leaves fix radiant energy to this
Chemical form
What are the raw materials of photosynthesis?
CO2 and H2O
What is the glucose product of photosynthesis stored as?
Sucrose and starch
This photosynthesis byproduct is essential for life
Oxygen
Photosynthesis reactions occur in this part of the leaf
Mesophyll
Mesophyll cells contain these for photosynthesis
Chloroplasts
Chloroplasts contain these pigments
Chlorophyll
What are the two wavelengths of visible light that chlorophyll absorbs the most?
Blue (400-500nm) and red (600-700nm)
In photosynthesis, absorbed light drives this process
Sugar synthesis
These structures in leaves regulate gas exchange
Stomata
This gas enters the leaf via stomata
CO2
This enzyme fixes CO2 into acid form
Rubisco
Carbon exits the leaf as this
Glucose (C6H12O6)
What leaf structure does carbon exit as glucose?
Vein
Mesophyll must be this in order for photosynthesis to occur
Saturated
H2O enters the leaf as liquid via these
Leaf veins
In what form does H2O exit leaves through the stomata?
Vapor
What is the process of leaf vapor exiting leaves through stomata called?
Transpiration
What two functions does transpiration serve?
Pulling water up from roots and cooling hot leaves.
These are cells that surround the apertures of stomates and can open and close
Guard cells
What 4 stimuli do guard cells respond to?
Light, humidity, CO2, root hormones
Stomata must be this in order to allow CO2 into leaf and to pull water up from soil
Open
Is the water gradient across stomata usually greater than the CO2 gradient?
Yes
Can open stomata lead to high water losses?
Yes
What percent of water taken up through plants is transpired?
90%
In what type of environment are stomata tightly controlled?
Dry environments
Are outer, exposed leaves more sinused than inner leaves?
Yes
Leaves in cooler, temperate environments have this type of leaf margin
Toothed
Leaves in warmer, tropical sites have this type of leaf margin
Entire
Primary forest leaves have this type of leaf margin
Entire
Secondary forest leaves have this type of leaf margin
Toothed
To reduce wind damage, larger leaves are often this
Compound
Does leaf size decrease with increased moisture and fertility?
No
Does leaf size decrease with increasing light and elevation?
Yes
Does leaf thickness increase with decreasing rain?
Yes
Does leaf thickness increase with increasing light and elevation?
No
Do smaller leaves tend to be simple leaves?
Yes
What are two characteristics of stomata in dry climates?
Recessed and fewer
Do sun leaves typically have less area?
Yes
Do sun leaves typically have shallower sinuses?
No
Do sun leaves typically have greater thickness?
Yes
Do sun leaves typically have shorter palisade cells?
No
Do sun leaves typically have more stomates?
No
Do sun leaves typically have more rubisco?
Yes
Do shade leaves typically have less area?
No
Do shade leaves typically have greater thickness?
No
Do shade leaves typically have reduced sinuses?
Yes
Do shade leaves typically have greater chlorophyll concentration?
Yes
Do shade leaves typically have more stomates?
Yes
What type of chlorophyll do shade leaves have more of?
Chlorophyll B
What wavelength of light are shade leaves adapted to absorbing?
Blue
On trees, a trunk is also known as this
Bole
This is lignified xylem vessels
Wood
This is a tough polymer of cell walls
Lignin
What two things does lignin provide?
Strength and decay resistance
Most of a tree is this type of cells
Dead cells
What are the two types of wood in boles?
Heartwood and sapwood
This type of wood is a core of dead xylem cells infused with resins and oils
Heartwood
What two things do resins protect wood against?
Decay and insects
What two properties do resins give to wood?
Color and odor
This type of wood is a cylinder of living cells around the heartwood
Sapwood
What two types of vascular tissue make up sapwood?
Xylem and phloem
What is the purpose of xylem?
To conduct water from roots to leaves
Gymnosperms have only this type of xylem cells
Tracheids
What two types of xylem cells do angiosperms have?
Vessels and tracheids
What is the purpose of phloem?
To conduct photosynthesized sugars away from leaves
What type of phloem cells do gymnosperms have?
Sieve cells
What type of phloem cells do angiosperms have?
Sieve tubes
These are plant tissues associated with growth
Meristems
These meristems are located at the tip of a stem/branch
Apical meristems
What type of growth do apical meristems create?
Longitudinal
What is another name for longitudinal growth in plants?
Primary growth
What plant organ do apical meristems create?
New buds/leaves
These are apical meristems found on stem/root tips
Stem meristems
These stem meristems form thin cylinders of dividing cells around stems/branches
Lateral meristems
What type of growth do lateral meristems create?
Secondary growth
What are the two types of cambium in lateral meristems?
Vascular and cork cambium
What does vascular cambium give rise to?
Vascular tissues
In vascular cambium, which way does xylem grow?
Inward
In vascular cambium, which way does phloem grow?
Outward
Where is cork cambium found?
Outside vascular cambium
What two types of tissue does cork cambium produce?
Cork and bark
What are two functions of bark?
Water conservation and protection
Lateral growth of woody tissues creates these
Growth rings
Growth rings occur in regions with these
Distinct growing seasons
This type of wood growth represents periods of rapid lateral growth
Earlywood
What is another name for earlywood?
Spring wood
This type of wood growth represents periods of slowed lateral growth
Latewood
What does latewood contain high concentrations of?
Resins
What is another name for latewood?
Summer wood
Are earlywood or latewood growth bands wider and lighter in color?
Earlywood
Are earlywood or latewood growth bands narrower and darker in color?
Latewood
This is the study of tree rings to date periods of time
Dendrochronology
What are the two types of tree form?
Excurrent and decurrent
What are five physical characteristics of excurrent trees?
Trunk continuous to the top; Many small lateral branches; Slender silhouette; Multi-layered canopy; Regular-spaced large leaves
What are four physical characteristics of decurrent trees?
Trunk split into lateral branches; Umbrella-shaped silhouette; Monolayer canopy; Regular-spaced large leaves
Which tree form is more shade tolerant and common in late succession?
Decurrent
Which tree form performs better in open environments?
Excurrent
What are the two types of tree roots?
Woody and non-woody
What are three physical characteristics of woody roots?
Large, perennial, have growth rings
What are two functions of woody roots?
Provide root system framework/support and carb storage
What are three physical characteristics of non-woody roots?
Small, fleshy/pliable/soft, and have root hairs
What are two other terms for non-woody roots?
Feeder or fine roots
What is the function of non-woody roots?
Water/nutrient uptake
Where are most non-woody roots found in the soil?
Upper few inches of soil
These meristems are tissues of cell growth at root tip
Root apical meristems
This protects the root apical meristem
Root cap
What are the three zones of root tips?
Zone of division, zone of elongation, zone of differentiation/maturation
This root tip zone is where newly formed cells grow in length
Zone of elongation
This root tip zone is where secondary walls form and root hairs develop
Zone of differentiation/maturation
This root tip zone is a region of meristematic tissue with rapidly dividng cells
Zone of division
These are extensions of root epidermis that develop in the zone of differentiation
Root hairs
What is the function of root hairs?
To increase surface are for water/mineral absorption
How long do root hairs survive?
2-3 weeks
This is a thin cylinder of dividing cells around all roots
Vascular cambium
Vascular cambium arises from this thin tissue layer in roots
Pericycle
What are three things produced by the vascular cambium in roots?
Xylem, phloem, side roots
This is the vascular cylinder in root meristems
Stele
What are three types of root systems?
Tap root, heart root, flat root
In this root system, one large central root extends down from main trunk, with lateral roots extending from it
Tap root
What are three examples of trees with tap root systems?
Hickory, walnut, white oak
In this root system, multiple primary roots extend laterally from the trunk, attach to numerous secondary roots, and grow mostly horizontally
Heart root
What are three examples of trees with heart root systems?
Red oak, sycamore, pines
In this root system, obvious primary roots are lacking, and roots grow and spread laterally
Flat root
What are four examples of trees with flat root systems?
Birch, spruce, maple, cottonwood
What are two common myths about tree roots?
That roots grow deep and do not extend past drip line
What are five environmental challenges that trees respond to?
Seasonal variations in climate; Chronic resource shortages; Variation in resource availability; Climate change; Changes in atmospheric chemistry
What are three ways trees respond to warm-cold seasonal variations?
Deciduousness, cold hardiness, and changes in cell chemistry
Why do trees drop leaves?
To conserve water
What are three changes tree cells make in response to warm-cold seasonal variation?
Losing water, gaining sugar, changing proteins
What are two cues for trees to adapt to warm-cold seasonal variation?
Light and temperature
This adaptation to seasonal variation decreases a plant’s lethal temperature over the winter, and is reversed with onset of spring
Cold hardiness
What are three adaptations of trees to wet-dry seasonal variation?
Deciduousness, photosynthetic bark, water storage tissues recharge
What are three adaptations of trees to chronic light shortage?
Leaf form/biochemistry plasticity; Adventitious buds that break in presence of light; Slow growth
What are two types of variation in water availability that affect trees?
Drought and flood anoxia
What are four tree responses to drought?
Stomata closure from the release of root hormones in dry soils; Deep taproots; Cells become more hypertonic to draw in water; Early leaf drop
What are two tree responses to flood anoxia?
Switching to fermentation; aerial roots from stem
How will many tree species have to respond to climate change (2 degree C rise by 2100)?
Shift range 200 miles north
What will a 200 mile north range shift require species to do?
Disperse 1-3 miles per year
Which type of forests are most at risk from climate change?
Cool northern forests
If climate change is slow, what will happen to cool northern forests?
They will be displaced by southern species
If climate change is rapid, what will happen to cool northern forests?
They will be replaced by grasslands
What are three other examples of forest types that are at risk from climate change?
Maple-beech, aspen-birch, spruce-fir
What are four risks that will rise with climate change?
Fire, drought, pests, diseases
By what percentage may burned areas increase with climate change?
25-50%
In some forests, modest temperature increases may raise this
NPP
More extreme temperature increases will do this to NPP
Reduce
Higher NPP from climate change will reduce this
Stream flow
More disturbance caused by climate change will reduce this
Water quality
What are three tree responses to higher CO2?
Rise in NPP; Rise in optimal growth temperatures; Reduced water loss
Are trees C3 or C4 plants?
C3
What is NOx found in?
Fossil fuel emissions
This acts as a fertilizer and may boost NPP
Nitrogen deposition
NOx does this to soil
Acidification
What are three things that happen due to soil acidification?
Nutrients leach; Toxic elements loosen; Microbial activity is reduced
This rises with warmer temperatures
Ground-level ozone
This is a strong oxidant that kills tissue and stunts plant growth
Ozone
