2. Question 1: Definitions
orographic precipitation – caused by the forcing of air masses over mountains; as air masses are lifted up the slope, they cool, and the water condenses, forming clouds.
albedo – reflectivity of a surface; example: snow has a very high albedo (0.9)
serotinous species – species with cones that are covered in resin. Fire melts the resin, freeing the seeds; example: lodgepole pine
vegetative reproduction – asexual reproduction/cloning; e.g., from roots rhizome, fragmentation, layering, etc.
genotype – true genetic makeup of a tree; it is never seen because of the effects of the environment

3. Question 1: Definitions (cont.)
outer bark – results from collapse of phloem as it is pressed to the outside; functions in defense and prevents water loss
rhizosphere – absorbing root/soil interface, it surrounds the root, living root hairs, mycorrhizae; it is where water and nutrient absorption take place
cavitation – formation of an air bubble in a xylem vessel as a result of extreme pressure during hot days; permanently blocks water transport in that vessel
shortwave radiation – radiation from the sun used in photosynthesis
vapor pressure deficit – physical measure of how dry the air is; it is the difference between the amount of water the air could hold at saturation (at a given temperature) and how much it actually contains

4. Phloem transports sugar/carbohydrate
Question 2: What are the main types of conducting tissue for (a) sugar/carbohydrate and (b) water transport in trees? How do their physical properties change seasonally?
Phloem transports sugar/carbohydrate
Transport from roots to shoots/leaves in the spring, from leaves to the rest of the plant in summer, and to the roots in the fall for storage
Xylem transports water
In spring, earlywood forms, allowing for increased water transport. As summer progresses and soil dries, there is a movement to formation of latewood, which is smaller in diameter and thicker. There is less water transport, but also less chance of damage to the xylem from cavitation.
Xylem is not part of the bark!

5. Question 3: What is meant by “cone crop periodicity”? Why does it occur? Why might two trees have the same periodicity and different levels of cone production?
Cone crop periodicity is the variation in cone production from year to year. There is maximum production during one year, followed by several years of reduced production.
This occurs because the plant will allocate photosynthate to cones one year and then need to supply more to the rest of the tree for several years and build the reserves necessary for another major cone crop.
Two trees would have the same periodicity to maximize the potential for cross-pollination. But, they may have different levels of production because of differing nutrient, water, or light availability.

6. Question 4: What is multiple flushing. Lammas growth
Question 4: What is multiple flushing? Lammas growth? How do they differ? Give examples of trees that might experience them (one for each).
Multiple flushing is the intermittent growth and development of buds and shoots throughout the season. This is common among trees with a long growing season, such as those along the coasts and in the southern US. (e.g., oak, maple)
Lammas growth, on the other hand, is the growth of dormant, fixed buds late in the summer in response to late summer rains. This is not healthy, because the buds do not have time to fully develop and harden before winter comes. This often occurs in young trees, particularly jack pine and Douglas-fir.
Multiple flushing has resting periods, not dormancy

7. Question 5: Does a wet surface or a dry surface heat up more under the mid-afternoon sun? Why? Does the color of the surface matter? Why? Use the appropriate equation in your answer, explaining each term.
A dry surface will heat up more because more of the incoming energy will be released as sensible heat flux (temperature), while most of the energy from the wet surface will be released as latent heat flux (evaporation).
Darker surfaces will absorb more energy, and therefore, will heat up faster than lighter surfaces, because the albedo of the darker surface is lower.
The equation we use to determine this is the Bowen ratio, such that β = λH / λE

8. Mycorrhizae are fungi that form symbiotic
Question 6: Many tree species have a symbiotic relationship with mycorrhizae. What are mycorrhizae? What is symbiosis? What impact does this relationship have on tree growth?
Mycorrhizae are fungi that form symbiotic
relationships with the roots of trees.
This relationship is mutually beneficial: trees get more water and nutrients, while the mycorrhizae get carbon from the tree to live.
Mycorrhizae dramatically increase the amount of surface area for nutrient and water uptake, so trees will grow larger and have a more extensive root system than they otherwise would have.
Mycorrhizae are fungi, not bacteria.
They do NOT fix nitrogen or carbon.
They serve to increase the surface area for nutrient and water uptake.

9. Question 7: What are the three methods of heat (energy) transfer discussed in lecture? Describe how heat is distributed in each method using the example of the wood stove in your answer.
Radiation – movement of energy through the air without assistance. When you pile on the logs, you will start to feel the thermal energy, even if there is no air movement in the house. As you continue to pile on the logs, the stove will start to glow with a reddish tint, which is the first visible sign of the radiation occurring.
Convection – transfer of heat via air movement; for example, the stove will heat the air above it, and this air will move with air flow throughout the room, warming the house (e.g., thermals).
Conduction – if you touch the stove, the contact will transfer heat from the stove to your hand. In addition, the water in the teapot will heat as the heat is transferred from the stove to the pot, and then to the water.

10. Question 8: What is osmotic potential
Question 8: What is osmotic potential? How do stomatal guard cells open and close?
Osmotic potential develops when a solute is added to one side of a semi-permeable membrane. This lowers the water potential of that liquid, causing water to flow in to equalize the potential.
Potassium enters the guard cell, creating osmotic potential. Water follows, and guard cells increase in length (not width) in response to turgor pressure. This forces them to open. The opposite occurs to close guard cells.