Forest Ecology & Silviculture Flashcards

Which of the following forest stand attributes is most directly measured by the 'basal area' metric?

Answer: The cross-sectional area of tree stems at breast height per unit area

Basal area is the sum of cross-sectional areas of all tree stems measured at breast height (4.5 ft), expressed per unit area (e.g., sq ft/acre), and is a key measure of stand density and growing stock.

In forest pathology, 'damping-off' of seedlings in a nursery is most commonly caused by which group of organisms?

Answer: Oomycetes such as Pythium and Phytophthora, and true fungi like Fusarium and Rhizoctonia

Damping-off is caused by a complex of soil-borne oomycetes (Pythium, Phytophthora) and fungi (Fusarium, Rhizoctonia) that attack seedling stems at or near the soil line, causing them to collapse.

The ecological concept of 'gap dynamics' is most relevant to understanding regeneration in which type of forest?

Answer: Shade-tolerant species-rich temperate and tropical forests managed under selection systems

Gap dynamics describes how small canopy openings created by individual tree death drive a fine-scale regeneration pulse in otherwise closed-canopy forests, which is most relevant to shade-tolerant species in selection-managed or old-growth forests.

A forester conducting a stocking survey uses variable-radius plot sampling (prism or angle gauge cruising). The basal area factor (BAF) of the instrument determines:

Answer: How much basal area each tallied tree represents per acre

The BAF determines the per-acre basal area represented by each tree counted as 'in' during a variable-radius plot cruise; multiplying the tally count by the BAF gives the stand basal area per acre.

Which of the following correctly describes the relationship between ectomycorrhizal fungi and their host trees?

Answer: The fungi form a Hartig net between root cortex cells and provide mineral nutrients in exchange for photosynthates

Ectomycorrhizal fungi form a mantle around the root tip and a Hartig net of hyphae between cortex cells without penetrating the cells, exchanging soil minerals (especially phosphorus and nitrogen) for carbon from the host.

The 'hydraulic redistribution' phenomenon observed in some forest tree root systems refers to:

Answer: Passive movement of water through roots from moist deep soil to dry shallow soil at night

Hydraulic redistribution (or hydraulic lift) occurs when deep roots passively transport water from moist deep soil layers upward to dry surface layers at night, indirectly benefiting shallow-rooted species and soil microbiota.

Under the 'four-class system' of Kraft crown classification, which crown class designation is given to trees whose crowns receive full light from above and at least one side?

Answer: Codominant

Codominant trees form the main canopy and receive full overhead light but have their crowns somewhat restricted on the sides by neighboring dominant trees, receiving full light from above and partial lateral light.