FNR 331 Exam 1

Definition of Biogeochemistry

study of the distribution and dynamic of chemical elements involved in movement and storage of energy in ecosystems

Geochemical

Cycling chemicals (nutrients) between ecosystems (ex: animal's waste moving)

biogeochemical

Cycling of chemicals within ecosystems (ex: decomposing litter)

Biochemical

Cycling of chemicals within individual organisms (Retranslocation, and Resorption)

Biological Mechanisms

Redistribution of nutrients via animal movement or migration

Geological/hydrological mechanisms

-Inputs via chemical weathering of rock and soil or dissolved nutrients moving into the ecosystem in soil water or stream water.

-Major input of nutrients in many systems is the geological processes of wreathing, erosion, and soil solution movement.

Nutrient Uptake by Plants

-Soil solution: direct uptake by roots

-Via mycotrophy: most forest plants highly dependent upon mutualistic relationship between their roots and mycorrhiza.

Critical Load

level of deposition above which resource impairment or harmful effects occur

Nutrient cycling (Role of Understory Vegetation)

Understories of most forests are low in biomass compared to the overstory-Forests w/pronounced shrub layer-Forests w/large biomass of bryophytes

How many soil arthropods are there in a square meter of soil?

930,300

Why are C4 plants more common?

They conduct photosynthesis more efficiently, but they still have a metabolic cost by creating 2 different enzymes to fix carbon twice- Energy Cost. It pays off when temperatures get warm enough and water becomes a limited resource after plants close their stomates. If it stays cool and a c3 doesn't have to close its stomates-it doesnt have photorespiration occur. Its fixing the carbon it needs without the 2 processes-Putting in less energy to get the same product. But when it gets warm c4 does better.

Photorespiration

Oxygen is fixed instead of CO2 which consumes the ATP that the plant needs to store energy in the form of carbohydrates.

Infrared

Long wavelengths, heat. Energy reradiated by the earth is of this type. Ex: pit vipers can see infrared radiation

ultraviolet

Can be seen by insects. For the production of vitamin D in human skin

What mechanisms lead to reduced competition?

-Great specialization

-Reduced resource demand

-Greater resource availability

-Increased predation

C4 Photosynthesis

The two-step photosynthetic pathway in which CO2 is first fixed in mesophyll cells to form 4-carbon acids, and then the 4-carbon acids are broken down into 3-carbon acids in the bundle sheath cells.

C3 photosynthesis

uses the enzyme RuBisCO in relatively inefficient conditions, to fix CO2 from the air and obtain the 3-carbon organic intermediate molecule 3-phosphoglycerate.

Forest Nitrogen Cycle

Nitrification into NO3 resulted in export of N via leaching into ground water and into stream

Aboveground

in many forests, constitutes the largest reservoir of biomass but lowest energy

Belowground

in many forests, it constitues a much GREATER annual turnover of organic matter and energy

Biological Integration

-Each level is the total environment of all the levels of biological organization below, and structural and functional component of the next level above.-Only 3 true levels: cells, individuals, and ecosystems.-Accurate predication of events or conditions can only be made on the basis of knowledge of the next true level of integration above the level of interest.

Trophic cascade

Occurs when predators limits the density and/or behavior of their prey and thereby enhance survival of the next lower trophic level.

CAM photosynthesis

Desert plants store CO2 at night to use during the day. Allows them to keep leaves closed during day and reduce water loss.

Hubbard Brook Experiment

Nutrients are being held in vegetation, and if they came down via litter fall they are being recycled (Biogeochemical cycle) once they enter the groundwater, and leave the watershed of that forest ecosystem, now they are in stream water (geochemical cycle)

Albedo

% of incident radiation that is reflected