SAF Forest Ecology & Silviculture 3 — Questions and Answers
Question 1: What is the primary ecological function of coarse woody debris (CWD) in a forest ecosystem?
- Increasing fire hazard uniformly across the stand
- Providing wildlife habitat and serving as a nutrient and carbon reservoir (Correct answer)
- Competing with regenerating seedlings for soil moisture
- Accelerating nitrogen loss through volatilization
Correct answer: Providing wildlife habitat and serving as a nutrient and carbon reservoir
CWD serves as critical habitat for cavity-nesting birds, amphibians, and invertebrates while slowly releasing nutrients back into the soil as it decomposes and storing significant amounts of carbon.
Question 2: Which of the following silvicultural treatments is specifically designed to concentrate growth on the best trees by removing competitors, and is most commonly applied in young stands?
- Crop-tree release (Correct answer)
- Improvement cutting
- Salvage cutting
- Sanitation cutting
Correct answer: Crop-tree release
Crop-tree release removes trees immediately adjacent to selected crop trees to free their crowns on multiple sides, concentrating diameter growth on the highest-quality individuals in young to mid-rotation stands.
Question 3: Nitrogen fixation in forest ecosystems is carried out by which of the following organisms associated with red alder?
- Mycorrhizal fungi of the genus Pisolithus
- Actinomycetes of the genus Frankia (Correct answer)
- Bacteria of the genus Rhizobium
- Cyanobacteria of the genus Nostoc
Correct answer: Actinomycetes of the genus Frankia
Red alder forms a symbiotic relationship with Frankia actinomycetes in root nodules, allowing the tree to fix atmospheric nitrogen and significantly enrich forest soils.
Question 4: The 'intermediate' crown class designation refers to trees that:
- Have crowns extending above the general canopy level
- Receive full overhead light but are overtopped on at least one side
- Receive limited direct sunlight and are mostly shaded from above (Correct answer)
- Have dead or dying crowns but living boles
Correct answer: Receive limited direct sunlight and are mostly shaded from above
Intermediate trees have smaller, crowded crowns that extend into the general canopy level but receive only limited direct light because they are largely overtopped by dominant and codominant trees.
Question 5: Which of the following best describes the 'masting' phenomenon in forest trees?
- Annual production of consistently high seed crops to ensure regeneration
- Episodic, synchronous production of large seed crops at irregular intervals (Correct answer)
- The process of seed dispersal by wind across long distances
- Vegetative reproduction triggered by drought stress
Correct answer: Episodic, synchronous production of large seed crops at irregular intervals
Masting is the synchronized, intermittent production of large seed crops (mast years) by a population of trees, thought to overwhelm seed predators and improve regeneration success in favorable years.
Question 6: In a forest stand subject to chronic browsing pressure from white-tailed deer, a forester is most likely to observe which long-term vegetation change?
- Increased dominance of palatable species like yellow birch and trillium
- Shift toward browse-resistant species like hay-scented fern and spicebush (Correct answer)
- Accelerated succession toward climax hardwood communities
- Increased structural diversity due to selective removal of dominant trees
Correct answer: Shift toward browse-resistant species like hay-scented fern and spicebush
Heavy deer browsing selectively removes palatable tree seedlings and forbs, causing a shift toward unpalatable or browse-resistant species such as hay-scented fern, which can then suppress tree regeneration for decades.
Question 7: The concept of 'carrying capacity' in a forest ecosystem context refers to:
- The maximum timber volume a site can produce per acre per year
- The maximum population of a species a habitat can sustain indefinitely (Correct answer)
- The total biomass of all organisms in a forest stand at one time
- The maximum number of trees per acre based on crown competition factor
Correct answer: The maximum population of a species a habitat can sustain indefinitely
Carrying capacity (K) is the maximum population size of a species that a given environment can sustain indefinitely, given available food, water, habitat, and other resources.
SAF Forest Ecology & Silviculture 3
What is the primary ecological function of coarse woody debris (CWD) in a forest ecosystem?