Module 1: Silviculture & Its Ecological Basis Flashcards
What is silviculture?
The art and science of controlling the establishment, composition, structure, and growth of a forest stand to meet the landowners’ objectives on a sustainable basis.
Three keys: it is manipulative. it is objective driven. it is sustainable.
It builds on many other disciplines: ecology, silvics, physiology, soils, measurements, economics, social science, etc.
Who sets the objectives for any silvicultural treatment?
The landowner (this could include public agencies)
What are the 3 keys to a silvicultural solution being appropriate, sustainable, or viable?
What are some constraints on these?
biologically possible
economically feasible
socially acceptable
Constraints: viable local markets depend on location of mills, accessibility, demand, terrain, laws, social acceptance, etc.
To know what is biologically possible, what must one understand?
What is the primary measurement for competition between trees?
Height (they are mostly competing for light)
What forms the basis for the roadmap used to get from the start to the end point?
Objectives (not always achievable) - define where you are going
Forest inventory data - gives you the starting point
What is a stand?
What factors influence the required environment of a silvicultural system?
What is a silvicultural system?
What 4 things should a silvicultural system accomplish?
–Sustain ecosystem health and productivity
–Improve tree growth and quality (quality does not always mean lumber quality!)*
–“Optimize” market and non-market benefits
–Shorten investment period and contain costs
*could mean mast production, longevity, aesthetics, carbon sequestration, etc.
What are the 3 parts of a silvicultural system?
What are the 2 main categories of silvicultural systems?
What are 4 factors that can be modified within a silvicultural system?
What are some factors considered when choosing a silvicultural method?
What non-timber considerations might cause you to apply a modification to a silvicultural method?
What is forest stand dynamics and what are its main elements?
Define forest disturbance and forest succession
Describe some ways in which forest disturbance varies.
tornadoes and hurricanes might be additional types of disturbance
“gap scale” disturbance describes when an opening is created, where typically adjacent plants/trees will fill it in
What are the 4 phases of stand development following a major (stand-replacing) disturbance?
Describe in detail how a forest stand progresses through the stages of development after a disturbance.
Describe the stand initiation stage in detail
Describe the stem exclusion stage of stand development in detail
Name and describe the 4 crown classifications
Describe the understory re-initiation stage of stand development in detail
Describe the old-growth or complex stage of stand development
Describe this graph
Stand initiation (reorganization phase): Rapid increase in the number of stems (establishment)—lots of stems, very little biomass.
Stem exclusion (aggradations phase): Begins at about crown closure; at peak density (TPA), characterized by density dependent mortality and an accumulation of biomass. Phase ends when biomass peaks.
Understory reinitiation (transition phase): Permanent understory forms-permanent canopy gaps form-mortality of individuals cannot be closed by adjacent individuals. Biomass declines as smaller individuals replace canopy dominants.
Old growth (steady-state)-total biomass of system fluctuates around some mean. The structure of the forest is self sustaining.
What are the typical time ranges for each phase of forest stand development for a central hardwood forest?
Stand initiation: 10-20 years
Stem exclusion: 10-70 years
Understory re-initiation: 50-120 years
Old-growth: 100 years or longer
Define respiration, in regards to plants
•Respiration is the process by which energy fixed by photosynthesis is made available for metabolic processes
What are the 5 environmental factors that influence photosynthesis?
- Light
- Temperature
- CO2 concentration
- Water availability
- Nutrient availablity
What specific light qualities are important to photosynthesis and tree growth?
What factors influence the light environment in a forest stand?
Describe this graph
Below some light level, carbon uptake is negative, as respiration exceeds photosynthesis. The plant is using its stored carbohydrates to fuel respiration at this point.
As light increases, a light compensation point is eventually reached where CO2 through photosynthesis is exactly balanced by losses through respiration
Above the light compensation point, photosynthesis increases until the amount of CO2 available to the leaf or processes and enzymes associated with the dark reactions limits photosynthesis. This plateau in the rate of photosynthesis is know as light saturation point
Compensation and saturation points vary among tree species, among individuals of the same species, among leaves on the same tree, and with changing environmental conditions.
What is CO2 concentration’s relationship to photosynthesis?
How does water availability affect the process of photosynthesis?
On what sites and areas in the US would you expect water to be a growth limiter?
What are the primary drivers of annual growth variation within a species of trees?
Seasonal weather patterns, overall climate, stand conditions, tree age
What is meant by ‘ecological legacy’ with regards to year-over-year tree growth?
Other than climate trends, what factors influence water availability in a given environment?
How does topography affect water availability?
How does nutrient availability affect photosynthesis?
What are factors on the plant itself that affect photosythesis?
Explain the carbon budget of a tree
What factors influence the amount of carbohydrates produced by a tree through photosynthesis?
What then influences the tree’s increase in mechanical support/stem diameter?
In what order does a tree prioritize allocation of its photosynthates (carbohydrates created through photosynthesis)?
Respiration is likely fixed as the top priority, it is possible that all lower functions could switch priority in certain conditions.
What is shade tolerance, and how is it used in silviculture?
Although we don’t have to know all the exact details, shade tolerance is not only about light. It also involves other factors specific to a tree or species like efficiency of water utilization and carbohydrate storage.
How is shade tolerance related to photosynthesis and the light saturation/compensation points of different tree species?
Shade intolerant trees’ higher light saturation point allows for faster growth in high light conditions (full sun)
Compare regeneration and ability to persist in the understory between shade tolerant vs intolerant trees
Compare the way shade tolerant and intolerant trees are generally able to respond to a release event
Compare crown characteristics and bole form of shade tolerant and intolerant species
Intolerant species would generally tend towards and excurrent crown form, while tolerant species would tend more towards decurrent crown form. There are always exceptions!
Looking at crown architecture of an overtopped tree can give a good indication of whether or not it might respond well to a release event.
Compare seed production between tolerant and intolerant species
Summarize the adaptive strategies of intolerant tree species
Summarize the adaptive strategies of shade tolerant species
advance reproduction: seedlings present and established prior to a disturbance event
What is Mean Annual Increment and how is it calculated?
What is periodic annual increment and how is it calculated?
What’s the relationship between PAI and MAI with regards to the rotation periods of fiber, sawtimber, and understory regeneration?
What is yield, gross yield, and net yield?
Gross yield includes live and dead trees. Net yield only includes live trees.
Describe site, site quality, and site index
What 3 main factors are strongly associated with the growth of individual trees?
What factor is the primary influence on height growth? What about diameter growth?
Height: site quality
Diameter: stand density
Summarize what happens with stand development as site quality increases
How does stand density influence height growth?
How does stand density influence diameter growth?
How does stand density influence mortality?
Explain these graphs
As density increases, overall biomass increases. This may be ideal if you are interested in a pulp/weightwood sale. However, past a certain point, the extreme density won’t allow enough volume per tree to develop to create merchantable saw timber.
