final (part 4 material) Flashcards
(33 cards)
What are pools and fluxes? How do you calculate turnover rate and residence time?
Pools: storage compartments of matter (e.g., carbon stored in fossil fuels).
Fluxes: movements of matter between pools (e.g., carbon released by burning).
Turnover rate = (Flux out / Pool size) * 100
Residence time = Pool size / Flux out
What is net primary production (NPP) and how might you measure it?
Net carbon available to consumers in an ecosystem; measured using biomass growth or satellite-based chlorophyll reflectance
NPP = GPP - autotroph respiration
How does NPP vary across the globe? What are some factors that affect NPP?
NPP varies by biome: highest in tropical forests and lowest in deserts and tundra.
Key factors: precipitation, temperature, and nutrient availability; too much rain can reduce NPP due to nutrient leaching
What is consumption efficiency?
Consumption efficiency = (Ingested energy / Available energy from previous level)
What is assimilation efficiency?
Assimilation efficiency = (Assimilated energy / Ingested energy)
What is production efficiency?
Production efficiency = (Energy to growth / Assimilated energy)
What is trophic efficiency?
Trophic efficiency = (Energy passed to next level / Energy in current level)
What is biomagnification?
Biomagnification is the increasing concentration of toxins (e.g., mercury, DDT) at higher trophic levels.
Especially problematic in gold mining regions and higher latitudes
What functions do N and P have in organisms?
Nitrogen (N): Essential for amino acids, proteins, enzymes, and DNA. It’s a critical component of chlorophyll in plants and is vital for growth.
Phosphorus (P): Needed for ATP (energy transfer), DNA, RNA, and phospholipids in cell membranes. It is crucial for energy storage and genetic material.
What are the different stages of the nitrogen cycle?
Fixation: N₂ gas → NH₃ (ammonia), via microbes, lightning, or industrial processes.
Nitrification: NH₄⁺ → NO₂⁻ → NO₃⁻ by microbes.
Assimilation: Plants absorb NH₄⁺ or NO₃⁻.
Ammonification: Organic N → NH₄⁺ from waste/dead matter.
Denitrification: NO₃⁻ → N₂ gas by anaerobic bacteria, releasing N₂ back to the atmosphere.
How does the nitrogen cycle interact with food webs?
N enters food webs when plants assimilate ammonium or nitrate.
It cycles through herbivores and predators via feeding.
Decomposers recycle N back into soil from detritus.
What are some ways that human activity affects the nitrogen and phosphorus cycles?
Industrial fertilizer production (Haber-Bosch process) increases reactive nitrogen.
Agriculture (N-fixing crops, fertilizer runoff) causes eutrophication.
Fossil fuel combustion adds nitrogen oxides to the atmosphere.
Mining and overuse of phosphorus-rich fertilizers affect aquatic systems.
Where does phosphorus come from and how does it cycle through ecosystems?
Comes from rocks and marine sediments, not from the atmosphere.
Weathering releases it into soil → taken up by plants → cycles through food webs.
Returns to soil via waste/decomposition and can bind to soil or leach into water.
How do scientists study decomposition? What are some factors that affect litter decomposition rates?
Methods: Use of litter bags, “Soil Your Undies” challenges, controlled field/lab experiments.
Factors: Moisture, temperature, chemical makeup (lignin/tannins vs. proteins/sugars), presence of decomposers (bacteria, fungi, soil invertebrates).
What are some examples of disturbances that would result in primary vs. secondary succession?
Primary succession: Glacial retreat, volcanic eruption (e.g., Mt. St. Helens), landslides—no life remains.
Secondary succession: Fires, floods, clear-cutting—some organisms and soil remain.
What life history traits typically characterize early succession/pioneer species vs. late succession/climax species?
Early/pioneer species: r-selected traits (fast-growing, short-lived, high reproductive output).
Late/climax species: K-selected traits (slow-growing, long-lived, competitive).
Does the successional trajectory in the Glacier Bay example support the Clementsian or Gleasonian views of succession?
Gleasonian. The study found multiple pathways and non-uniform outcomes depending on location and proximity to refugia, supporting individualistic species responses, not a fixed climax (Clementsian view).
Describe the three models of succession.
Facilitation: Early species modify environment, making it suitable for later ones.
Inhibition: Early species prevent others from establishing; later species dominate due to longer life.
Tolerance: All species can colonize, but those tolerant of limited resources dominate over time.
How could animals accelerate or impede the succession of plant communities?
Accelerate: Soil invertebrates (e.g., nematodes, beetles) enhance decomposition and nutrient cycling.
Impede: Seed predation (e.g., deer mice eating tree seeds) reduces regeneration and slows succession.
What is the field of biogeography?
Biogeography studies the geographic distribution of species and communities through geological time
What is Wallace’s line and its cause?
A biogeographic boundary separating Asian and Australian fauna, caused by deep ocean trenches that prevented species migration during low sea levels
What is the relationship between vicariance and disjunct ranges?
Vicariance: a once continuous range is split by a barrier (e.g., mountains, oceans).
Leads to disjunct ranges: related species found in widely separated locations
What are some unique features of plants in the tropical rainforest biome?
Evergreen, thick leaves with drip tips
High chemical defenses in leaves
Shallow roots with buttresses
Lianas (woody climbers), epiphytes, and nitrogen-fixing epiphylls
What are hyperdominant Amazonian tree species?
A small number of tree species dominate Amazon biomass and stem count.
