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69 Cards in this Set

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Describe the soil horizons given in class.
O horizon = organic matter, decomposing but not yet decomposed (i.e.
leaf litter, poo) microbial community

A horizon = products of decomposition… CO2, Nitrates, Phosphates,
nutrients BUT –maximum eluviation (leaching). Top of mineral soil

B horizon = maximum illuviation –deposition of leached elements

C horizon = underdeveloped mineral layer

R horizon = bedrock layer
What is cation exchange capacity?
• Measure of soils ability to absorb cations –most important nutrients are cations, organic matter increases CEC
Why is soil pH important?
pH affects nutrient availability

best for most crops is slightly acidic soils

Very acidic – H binds to clay particles, displace nutrient cations which leach out

Very alkaline – other cations (exchangeable bases) reduces CEC

Nutrient cations bind too tightly to soil (polyvalent cations) but plants can’t take them up.
What are the water and nutrient holding capacities of different kinds of soils?
Sandy soil = poor water & nutrient holding capacity

Silty soil = intermediate characteristics

Clay soils = good water and nutrient
What’s a loam?
Soil with a “good” balance of sand, silt, clay
How are soil structure, texture, and porosity interrelated?
Texture influences porosity by the relative amount of different sized particles (e.g. more clay = lower porosity

They all fit together as pieces into a whole that determines the amount of nutrients, water, and other products a soil can contain.
What are soil structure, texture, and porosity?
Structure –physical arrangement of particle –affects porosity

Texture –relative proportions of different sized particles affects porosity

Porosity –total volume of pores and pore size
Influences gas exchange in soils (aeration)
Affects H2O holding capacity
What are the components of soils?
Complex of:

1. Parent material –mineral component (was rock)

2. Organic material –litter input (leaves, twigs); dead stuff; wastes = detritus

3. Air Spaces full of gases and/or water (atmospheric gases –nitrogen, oxygen, CO2)

4. Solutes –dissolved in the water

5. Living things –such as bacteria and fungi, symbionts, pathogens, parasite, herbivores
What are some physiological adaptations?
heat shock proteins

can have alternative enzymes kick in

can have alteration of the membrane lipids

tiny leaflets: smaller surface area cool more readily
What are some leaf adaptations to hot/dry/sunny or moist/shady environments?
Pubescence/color –reflective

Leaf Angle –vertical –less direct radiational loading

Moist: large leaves cooled through transpiration
Review the factoids given in the soils lab (NOT the methods).
Phosphates are given up in the soil but most are chemically bound and unavailable for plant uptake

Nitrogen from the atmosphere is the ultimate source of soil N, but much of it also comes from wet and dry atmospheric deposition and from decomposing organic matter such as leaves and animal detritus

Plants can take up nitrates but NOT nitrites
What are the characteristics of mollisols, spodosols, alfisols, oxisols, entisols, and
aridisols?
Alfisols –temperature deciduous forests; good O horizon; significant clay component; fertile soils

Spodosols – coniferous forests; very acidic; not very fertile

Mollisols – grasslands –”best” agricultural soils; very thick layer of organic matter; annual plants and root turnover

Oxisols – tropical rain forest oldest soils; not very fertile; most of the nutrients are held in the biomass; trees are evergreen (leaves aren’t dropped every year); massive leaching

Aridisols – desserts; “bad” soils; very little organic input (not much there to die); high pH; any nutrients that are there are really tightly bound by soil and not readily taken up; caliche layer (calcium and other salts) because you have high evaporation and low precipitation

Entisols – very young; underdeveloped; variable fertility
What defines a soil as being saturated, at field capacity, or at
wilting point?
Saturated – all pore spaces full of water; not very good to have all the time because it creates anaerobic conditions in root zone

Field capacity – small pore spaces saturated; large have drained (percolation through soil)

Wilting point – the water in the soil is held too tightly to be taken up

Hygroscopic – hygroscopic coefficient –absorbed H2O @ 50% humidity
Why do soil porosity and texture matter?
They matter because they determine the nutrient quality and holding ability as well as the water holding capacity
What’s the main adaptation to cold?
Tough needles (conifers)

Purposely loose water content (frost hardening)

Halting metabolism
What is leaf characteristic dimension? What does it influence?
size and shape influences formation of a boundary layer and a small boundary layer can cool more easily
What conductances are important in transpiration?
Stomatal conductance

Boundary layer conductance
What is transpiration and what is the driving force for transpiration?
Evaporation from leaves

Vapor pressure deficiet of the air influenced by temperature and moisture; the hotter the more moisture it can hold
What are conduction and convection?
Conduction –direct contact –one substance or another (Important in soil)

Convection –air flow (fluid)
What are the various components of the energy balance equation?
Qnet = net radiation

QH = sensible heat –temperature

QE = Latent heat –evapotranspiration cooling process

Qs = storage –depends on tissue –laws of physics

Qm = metabolic –negligible in plants

Qcc
o Conduction –direct contact –one substance or another (Important in soil)
o Convection –air flow (fluid)
What is latent heat exchange and why is it important?
Latent, or hidden heat determines level of evaporation and can affect energy balance/enzymatic activity.
What are active, optimal, and lethal limits in terms of temperature?
Active = Range of activity (metabolic)

Optimal = Best range for most metabolic activities

Lethal = Compatible with life
What is osmoregulation and how does it help a plant deal with low soil moisture?
Osmoregulation is the active regulation of the osmotic pressure of an organism's fluids to maintain the homeostasis of the organism's water content; that is it keeps the organism's fluids from becoming too diluted or too concentrated. How does it help deal with low soil moisture?
Describe various physiological, anatomical, and morphological adaptations and acclimations to low water availability.
Drought Avoidance

Drought Deciduousness

Drought Tolerance
physiological
anatomical/morphological
phreatophytes
root/shoot ratio
leaf adaptations
succulents
sunken or encrypted stomata
xylem modifications
Distinguish between aquatic plants, hygrophytes, mesophytes, xerophytes, and halophytes.
Aquatic plants – submerged/floating –both

Hygrophyte –permanently moist/wet soil (like a bog)

Mesophyte –wet/dry/wet often moist rarely super dry

Xerophytes –prolonged dry periods

Halophytes –saline soils (plants must overcome the soils tendency to hold onto water)
What are WUE’s various measures?
Biomass/transpiration

Biomass/per amount of H2O applied (often used in agriculture)

Yield/H2O applied (often used in agriculture)
What is water use efficiency?
there is a trade off between closing stomata to conserve water and the need to take up CO2 for photosynthesis WUE is a measure of this trade off

• WUE = A/E (and others)
o A is CO2 assimilation
o E is evapotranspiration
What’s the relationship between VPD and humidity?
VPD varies within the day and the season so it greatly affects humidity. Small changes in VPD = big changes in water density of the air.
What is a boundary layer and what affects it?
The Boundary layer is the still air around and underneath the leaf. Size and shape of the leaf determine the boundary layer. Big leaves vs. Fern.
What’s the relationship between VPD and humidity?
VPD varies within the day and the season so it greatly affects humidity. Small changes in VPD = big changes in water density of the air.
What conductances are important in transpiration?
Stomatal conductance

Boundary layer conductance
What is transpiration and what is the driving force for transpiration?
Evaporation from leaves

Vapor pressure deficiet of the air influenced by temperature and moisture; the hotter the more moisture it can hold
How does water potential differ in the various components of the SPAC?
Soil has the highest water potential

Plant –intermediate
Air –lowest exponentially lower

This is why water moves through plants w/o energy expenditure

Water potential (Ψ) is expressed in units of pressure
What is the SPAC?
(Soil Plant Air Continuum)

Soil has the highest water potential

Plant –intermediate

Air –lowest exponentially lower

This is why water moves through plants w/o energy expenditure

Water potential (Ψ) is expressed in units of pressure
What are (Water Potential) its components?
Ψo = usually negative
Ψp = usually positive
Ψm = usually negative (in soil)
Ψg = usually negative (in soil)

Ψo –osmotic –solute concentration in cells plants can digest this
Ψp –pressure –turgor pressure
Ψm –matric potential –how strong is soil’s hold on water
Ψg –gravimetric –gravity’s pull on water towards earth


More negative number = a drier, more water stressed plant

Difference in potential energy between pure H2O and a solution
What's water potential?
measure of water status
Describe the characteristics that allowed plants to live on land and then move away from water to colonize the earth.
Waxy cuticle

Vascular tissue (mosses lack these and will be restricted to environments close to water)

Mycorrhizal associations

Spread to diverse environments –pollen & seeds

Ferns and etc… are limited to moist places because they don’t have pollen they have spores and swimming sperm
What are the ways that plants use water?
Turgor pressure (helps tissue stand up)

Transpirational evaporative cooling –keep stomata open

Most water taken up just passes through

Reactant in photosynthesis
What is Plant Ecology?
The study of the environment with respect to plants. duh!
Components of the biotic environment?
Reproduction, mutualism, seeds/pollen, mycorrhiza, competition for nutrients(The main focus of Ecology)
Components of the abiotic environment?
Soils, water, temp, CO2, light. All the most important factors with animals.
Organizational hierarchy--
Organismal/individual
The basic unit of ecology, identify mechanisms that give rise to diversity of life.
Organizational hierarchy--
Population
Groups of individuals occupying the same geographical location.
Organizational hierarchy--
What is a Community?
population + ecosystem = community
Organizational hierarchy--
What is a System(s)?
How yearly rainfall affects productivity, all biotic and abiotic elements in a given area.
Organizational hierarchy--
What is Landscape Ecology?
Ecosystems + communities = Landscape Ecology
Scientific method what are the steps? 1-4
acronym O.Q.H.P.H.
1 Observations
2 Questions
3 Hypothesis
4 Predicitons
Scientific method
acronym O.Q.H.P.H.
#5
#5 Hypothesis testing
1)If experiment agrees with predictions, further hypothesis will be expanded and predicted scope of problem
2) If experiments are not consistent with the predictions, then conceptual model must be reconsidered.
3 Types of ecological research
a) Controlled experiments
b) Natural experiments
c) Observational experiments
Scale of research can be conducted in 2 ways.....
a) Spatial (latitude, atmospheric moisture, position in forest)
b) Temporal (time of day, or season)
Specific Scale and Heterogeneity give rise to....
Effective Ecological Research
How does climate vary around Oklahoma?
More rain = longer growing season, most --> least, SE --> NW. See precipitation data lab #1
What is the main point of the light reactions of photosynthesis?
6CO2+6H2O+light --> C6H12O6+6O2+ATP
What is the main point of the Calvin Cycle (C3)?
1) Fix CO2
2) Make simple sugars
Regarding the Calvin Cycle, what is used and what is produced?
RuBP(5-carbon) + CO2, ATP +NADPH reduce CO2 to make Triose Phosphates(G3P's)
What are the main factors that limit photosynthetic rate?
1) Light
2) CO2 availability
3) Stomata closure
4) Temperature/enzymatic fluidity
How do these factors (photosynthetic rates) vary over time?
Via seasons(temporal) and atmospheric CO2 availability. CO2 ppm .0035 --> .0037
What are PAR and PPFD?
Photosynthetically Active Radiation and Photosynthetic Photon Flux Density.
What is light compensation point? vs. light saturation point(s)?
LCP is the amount of light (PAR) at which net photosynthesis is zero. Carbon loss equals carbon uptake. 4-7p.m.
What is light saturation point?
The condition of maximum photosynthesis now only limited by dark reactions. 10a.m.-12
High energy wavelengths are short or long?
Short!
Low energy wavelengths are?
Long. Analogous to low hearing frequency.
(PAR) photosynthetically active radiation is considered between __nm and __nm?
400 nm & 700 nm.
Name characteristics of Sun Leaves?
1) Less surface area
2) Thicker (nm)
3) More stomata
4) Big investment in biomass (Think umbrella leaf!)
Name characteristics of Shade Leaves?
1) Thin/Broad
2) Fewer stomata
3) More chlorophyll per cm2
4) Lower light saturation point
Adaptations to light levels include........
1) Horizontal arrangement, receives mid-day sun.
2) Vertical arrangement, receives morning and evening sun.
3) Cupped arrangement, disperse light.
4) Solar Trackers, just plain cool!
Ohm's law =
Current = Voltage/resistance

Conductance = 1/resistance
Driving Force =
(Ca - Ci)
Ca = carbon atmospheric CO2
Ci = carbon internal CO2
What is the driving force of CO2 uptake?
Internal CO2 levels
remember Atmospheric - Internal = Driving Force
(Ca - Ci)