FM Soil Science & Hydrology Flashcards
7 cards from real FM practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 FM Soil Science & Hydrology flashcards as text
How does coarse woody debris (CWD) on the forest floor primarily benefit watershed hydrology?
Answer: Retains soil moisture and reduces erosion by slowing runoff
Coarse woody debris acts as a physical barrier that slows surface water movement, promotes infiltration, retains moisture, and reduces erosion by intercepting runoff.
What is the primary hydrological concern when clear-cutting occurs in or near riparian zones?
Answer: Increased stream sedimentation and elevated stream temperatures
Removing riparian vegetation eliminates shade (raising stream temperature), disrupts root networks that stabilize banks, and allows sediment from exposed soils to enter streams.
Forest soil pH is primarily influenced by which combination of factors?
Answer: Precipitation, parent material, and organic matter decomposition
Precipitation leaches base cations, lowering pH; parent material determines base mineral supply; and decomposing organic matter releases organic acids that further acidify forest soils.
Which field practice best reduces sediment delivery to streams during timber harvesting on slopes?
Answer: Installing water bars and cross-drains on skid trails
Water bars and cross-drains intercept concentrated flow on skid trails and divert it into vegetated areas before it gains sufficient energy to transport large sediment loads to streams.
Evapotranspiration (ET) in a forest ecosystem refers to:
Answer: The combined loss of water to the atmosphere via soil evaporation and plant transpiration
ET is the sum of direct evaporation from soil and canopy surfaces plus transpiration through plant stomata, and typically represents the largest water output from a forested watershed.
What minimum riparian buffer width do most US state forestry Best Management Practices recommend for protecting small perennial streams during timber harvest?
Answer: 50–100 feet
Most state BMP guidelines specify 50–100 foot streamside management zones (SMZs) for small perennial streams, balancing water quality protection with operational flexibility, though exact widths vary by state and slope.
The rate of forest floor litter decomposition is primarily controlled by which set of factors?
Answer: Temperature, moisture availability, and microbial/fungal activity
Decomposition proceeds fastest under warm, moist conditions with active microbial and fungal communities; these three interacting factors regulate nutrient cycling rates in forest soils.