Silviculture Foundations
This term describes the art and science of controlling the establishment, growth, composition, health, and quality of forests to meet diverse needs and values.
What is silviculture?
King's Site Index expresses the expected height of dominant and codominant trees of a given species on a site at this specific base age.
What is 50 years?
This type of seed, collected from genetically improved parent trees in a controlled setting, is preferred over woods-run seed when high growth rates and disease resistance are desired.
What is orchard seed (seed orchard seed)?
Pre-commercial thinning differs from commercial thinning in this fundamental economic way.
PCT generates no merchantable revenue, the trees are too small to sell, while commercial thinning pays for itself through timber sales
This harvest method removes all merchantable trees in a single entry, creating a large opening that favors shade-intolerant regeneration.
What is a clearcut?
When conducting stand typing, this process of combining areas with similar characteristics into fewer, larger units is called _______, as opposed to splitting.
What is lumping?
These three guiding questions: What is possible? What is profitable? What is ____? can be a framework for every silvicultural decision.
What is political (or permissible)?
This density metric represents the diameter of the tree of average basal area in a stand — it is more resistant to outliers than arithmetic mean diameter.
What is Quadratic Mean Diameter (QMD)?
Seed dormancy delays germination until conditions are favorable — these two environmental triggers can break dormancy in Pacific Northwest conifers.
What are any two of: cold stratification (chilling), moisture, light, scarification, temperature fluctuation?
Two answers: When thinning from below, you remove trees from this portion of the canopy; thinning from above targets this other portion.
What is thinning from below removes suppressed/understory trees; thinning from above removes dominant/codominant trees?
In the Capitol Forest study, this harvest method was designed to maintain two distinct age classes — an overstory retained for seed and a newly establishing understory cohort.
What is a two-aged stand (shelterwood or seed tree) harvest? Mixed age is acceptable but the most accurate definition would be a two aged stand
Laminated root rot is caused by this pathogen and tends to persist in a stand through this mechanism.
What is Phellinus (now coniferiporia) sulphurascens; it persists through root-to-root contact and infected stumps/root systems remaining in the soil?
This type of management maintains a single age class across the stand, with all trees established and harvested within a relatively short window.
What is even-aged management?
Curtis' Relative Density is calculated using basal area per acre and this second stand variable.
What is Quadratic Mean Diameter (QMD)? (RD = BA / √QMD)
You have two seedling options for a high-elevation, north-aspect replant after a clearcut: a P+1 container plug and a 2+0 bareroot. The site has late frost risk and a short planting window. Defend which stocktype you would choose and why.
the P+1 container plug is likely preferable: intact root plug reduces transplant shock, earlier planting is possible, and the contained moisture buffer helps on a challenging site. The 2+0 bareroot may be larger but root exposure during lifting/storage increases frost and desiccation risk on a compressed planting window.
A forester plants at 10x10 spacing (438 TPA) even though the final harvest goal is 180 TPA. Name one economic or silvicultural advantage of this approach.
Examples: early canopy closure suppresses competing vegetation; self-thinning selects strongest individuals; more leave-tree options during PCT; maximizes early growth potential
Disturbance emulation in silviculture means designing harvest methods to mimic________, in order to maintain biodiversity and ecological function.
What is natural disturbance (e.g., wind, fire, insects) in terms of patch size, structural retention, and spatial pattern?
A snag, or biological legacy, in a stand can indicate several things about forest health — name two ecological roles snags play or two things their presence might tell a manager.
What are any two of: wildlife habitat (cavity nesters), nutrient cycling, past disturbance/disease, stand age indicator, coarse woody debris recruitment?
Name two ecosystem services that forests provide, as discussed in Nyland Chapter 1.
What are any two of: clean water, clean air, wildlife habitat, timber, carbon sequestration, recreation, soil stability, biodiversity?
A Douglas-fir stand has an RD of 75. Based on stand dynamics, describe what is likely happening in this stand.
What is intense competition — the stand is approaching or at full site occupancy, likely experiencing competition-induced mortality and slower individual tree growth?
Frost encapsulation protects seedling buds by coating them in ice — explain the mechanism by which this actually prevents freeze damage.
The ice releases latent heat as it forms, holding tissue at 32°F or above rather than dropping to the damaging sub-freezing air temperature
On a density management diagram, the zone between the lower stocking threshold and the zone of imminent competition mortality defines this management target.
What is the managed density zone (optimal growing space / between crown closure and full site occupancy)?
The Forest Vegetation Simulator (FVS) is a modeling tool — describe one way a silviculturist would use it in planning a management regime.
What is any of: projecting stand growth over time, simulating thinning/harvest outcomes, modeling mortality, comparing silvicultural regimes, estimating future timber volumes?
These five key criteria are used when conducting stand typing
What are species composition, stand structure, stocking density, age class, and site quality?
Silvics and silviculture are related but distinct disciplines. A forester says 'knowing that Douglas-fir is shade-intolerant is silvics; deciding to clearcut based on that is silviculture.' Explain why this distinction matters operationally.
What is silvics describes the biological characteristics of a species (ecology, physiology, autecology); silviculture applies that knowledge to make management decisions. The distinction matters because a manager must understand species biology before designing treatments — silvics informs, silviculture decides.
This stand metric compares a stand's basal area and trees per acre to a historically defined 'normal' or fully stocked stand from yield tables.
What is percent normality?
This silvicultural practice — using Red Alder on wet disturbed sites before planting conifers — improves soil fertility through this ecological process.
What is nitrogen fixation (Remember: Red Alder fixes atmospheric nitrogen via root symbiosis with Frankia bacteria)?
Removing epicormic branches as part of a stand treatment improves this specific wood quality characteristic.
What is knot-free (clear) wood quality / lumber grade?
A 30-year-old Douglas-fir stand has an RD of 38. Your density management diagram shows the lower threshold for crown closure at RD 25 and the onset of competition mortality at RD 55. Should you thin now?
no — at RD 38 the stand is within the managed density zone, above crown closure but well below the mortality threshold. Thinning now would sacrifice growth potential; the stand has not yet reached the point where competition is limiting individual tree growth or causing significant mortality. Monitor and plan entry when RD approaches 50–55.
Dwarf mistletoe differs from most forest pathogens in this important way — it is not a fungus or bacterium but rather this type of organism.
What is a parasitic flowering plant (angiosperm)?