Lecture 09: Nutrient flows Exam Questions

What are two ways human activities add N to the biosphere?

Answer: Energy production in the form of NOx and agricultural fertilization in the form of NHx

Describe a riparian zone.

A riparian zone is an ecotone between aquatic and upland terrestrial ecosystems that is exposed to lateral water flow. They have a high water table because of their proximity to aquatic ecosystems, and are always located in or near river channels directly affected by river flow. Often these areas will experience intermittent flooding, supporting wetland plants that will survive occasional flooding. These areas can be very effective nutrient buffers between agricultural areas and watersheds.

What are the functions of the three riparian buffer zones?

Zone 1: undisturbed forest roots serve to reduce erosion,
Zone 2: managed forest allows for multiple types of nutrient uptake and are therfore more effective at absorbing nutrients
Zone 3: runoff control, mostly grasses have a lot of root mass slowing down the water and collecting nutrients

Identify and discuss the major chemical processes of the nitrogen cycle.

What is a Hypoxic zone? How do they form?
A hypoxic zone is an area in a body of water that has little to no dissolved oxygen suspended in the water column. They form when nutrient-rich water from rivers flows into a larger body of water, for example the ocean, causing massive algal blooms. As these algae die, they sink to the bottom of the ocean. Decomposition converts oxygen into CO2, suffocating all organisms reliant on aerobic respiration.

Explain some of the limitations of the Stella model created in the first LAB (Forest NEP). What could be added to the model to make it a more accurate representation of real situations? (think stocks, flows, other influences on NEP production) Identify and explain at least 2 items
sample items:
-stock representing the amount of C in the atmosphere
-stocks of N/fluxes of N above/below ground
- P stock/fluxes
-N's or P's impact on NPP

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