Of Ecosystem Processes Flashcards
7 cards from real Ecology practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Of Ecosystem Processes flashcards as text
Which process releases carbon dioxide from an ecosystem's soil back into the atmosphere?
Answer: Soil respiration
Soil respiration—from microbial decomposition and root respiration—is the second-largest carbon flux from terrestrial ecosystems to the atmosphere.
What is 'allochthonous' organic matter in a stream ecosystem?
Answer: Organic matter entering the stream from surrounding terrestrial sources
Allochthonous inputs are organic materials (leaves, wood, insects) that originate outside the stream and subsidize aquatic food webs.
Which of the following describes the 'spiraling length' concept in stream nutrient dynamics?
Answer: The downstream distance a nutrient travels before completing one cycle of uptake and release
Spiraling length measures nutrient retention efficiency: short spirals indicate tight retention, while long spirals mean nutrients travel far before cycling.
What ecological process moves calcium from soil minerals into living organisms and back?
Answer: The calcium cycle driven by weathering, uptake, and litterfall decomposition
Calcium enters ecosystems through mineral weathering, is taken up by plants, and is returned to the soil through decomposition of organic matter.
Which term describes an ecosystem that releases more carbon to the atmosphere than it absorbs?
Answer: Carbon source
A carbon source emits more CO₂ (or CH₄) than it sequesters, contributing to atmospheric greenhouse gas concentrations.
How do mycorrhizal fungi contribute to nutrient cycling in forest ecosystems?
Answer: They extend the plant's effective root surface area to acquire phosphorus and other nutrients
Mycorrhizal hyphae greatly increase the volume of soil a plant can explore, dramatically improving uptake of phosphorus and other immobile nutrients.
What is the significance of the 'redox potential' of soils for ecosystem nutrient cycling?
Answer: It controls which microbial processes operate, affecting nitrogen, sulfur, and iron cycling
Redox potential indicates whether soil is oxidized or reduced; low redox conditions (waterlogged soils) favor anaerobic processes like denitrification and methanogenesis.