20: Nutrient Cycling & Biogeochemical Cycling Flashcards
Pathway of an element or nutrients through an ecosystem
Nutrient cycling (at the ecosystem level)
The exchange and movement of elements or nutrients between the physical environment and living organisms. Much larger spatial scale the nutrient cycling.
Biogeochemical cycling (at the biosphere scale)
What controls the availability of essential elements and minerals?
Their inputs, transformations, and outputs.
What are the rates of inputs, transformations, and outputs related to?
The interactions among organisms and their interactions with the environment
What is the original source for all essential elements?
The physical environment (big bang)
What are the two types of biogeochemical cycles?
Gas and sedimentary
What does the gaseous biogeochemical cycle include?
The atmosphere and the ocean
What does the sedimentary biogeochemical cycle include?
Soils, rocks, and minerals move
Where the three primary elements required for life?
Carbon, nitrogen, and phosphorus
Major carbon pools
Atmosphere; marine and terrestrial soils; fossil fuels; autotrophs and heterotrophs
What represent to the largest CO2 pools?
The atmosphere and water (mostly Ocean)
What are the major processes that control the flux of carbon between the atmosphere and the living environment?
Photosynthesis and respiration
The movement of nutrients between one nutrient pool and another
Flux
What moves carbon from the atmosphere to autotrophs (or from the water to aquatic autotrophs)?
Photosynthesis
What does photosynthesis do?
Transforms CO2 into organic carbon
What moves carbon from autotrophs or heterotrophs to the atmosphere?
Respiration
What does respiration do?
Transformed organic carbon into CO2
What controls how much carbon will be stored in primary producers?
Gross primary production
Which abiotic factors influence the rate of gross primary production and thus the flux of CO2 from the atmosphere to the living environment?
Nutrients, temperature, and precipitation
What controls how much carbon will move up the food chain?
Consumption rates and production efficiency of consumers
What controls how much carbon will be returned to the atmosphere or water as CO2?
Respiration rates
Based on production efficiencies alone which taxa allows for more organic carbon to be cycled up the food web? Invertebrates (30-40%), ectothermic vertebrates (~ 10%), or endothermic vertebrates (1 to 2%)
Invertebrates
What is the major control over returning organic carbon in fossil fuels to the atmosphere as CO2
The rate of fossil fuel use by humans
Major nitrogen pools
Atmosphere (largest), soils, water, and organisms
Convert N2 gas to nitrate + nitrate or ammonia, which are usable forms to plants
Nitrogen fixtures (Nitrification)
List three nitrogen fixers
Cyanobacteria, Free living bacteria, root associated bacteria
Generates enough high-pressure and energy to perform nitrogen fixation
Lightening
What gets nitrogen into the food web?
Nitrification and Ammonification
Transforms nitrate back to N2 gas
Denitrification (done by bacteria)
How have humans altered the N cycle?
Haber-Bosch process (artificial N fixation for fertilizer)
Major pools of phosphorus
Largest pools occur in mineral deposits and marine sediments
What is the major way in which phosphorus is released from minerals?
Weathering. Once released into soils a can be taken up by plants
A fungus that grows on plants roots. it has a symbiotic relationship with plants that help plants absorb nutrients
Mycorrhizae fungi
Phosphorus can enter the food web once it has been?
taken-up by plants
What are the major processes for P to enter the food web?
1-Weathering. 2-Mycorrhizae fungi transfer nutrients to plants. 3-Herbivory enters phosphorus into the heterotrophic food web
not evenly distributed across the world, but we can make more available by mining it from rock
phosphorus
How have humans altered the P cycle?
China, Morocco, and Western Sahara largest producers of mined phosphate. 80% US production comes from 10 mines in Florida and 1 mine (world largest) in North Carolina
breakdown of chemical bonds that were formed during the constructions of plant and animal tissue
decomposition
converts organic compounds into inorganic nutrients that can be taken up by plants
decomposition
involves high rates of respiration that convert organic C to CO2 releasing it back to the atmosphere
decomposition
Processes of Decomposition
Leaching, Fragmentation, Ingestion, and Excretion of Waste
removal of soluble nutrients from a substance through the percolation of water
leaching
breaking down of smaller parts. increases surface area allowing more bacteria to colonize , increasing rate of decomposition
fragmentation
Major controls on decomposition
temperature and precipitation
Which biome is the largest source of CO2 to the atmosphere due to high rates of decomposition? tundra, tropics, desert, or boreal forest
Tropics
can be a major source of new nutrients
decomposition
