Chapter 55 Ecosystems and Restoration and Ecology Flashcards
What is an ecosystem?
Consists of all the organisms living in a community, as well as the abiotic factors with with they interact
What is the range of an ecosystem?
It range from a microcosm to a very large area such as an island
What are the two main processes of an ecosystem?
- energy flow
- chemical cycling
What does energy flow do? What does chemical cycling do?
- Energy flows throughout the ecosystem
- Chemical/matter cycles within ecosystems
What is the first law of thermodynamics?
States that energy cannot be created or destroyed, only transformed
How does energy enter an ecosystem?
How does energy exit an ecosystem?
- Enters as solar radiation/sunlight
- Exits as lost heat
What is the second law of thermodynamics?
States that every exchange of energy increases the entropy of the universe
What does the law of conservation of mass state?
States that matter cannot be created or destroyed
What does it mean if ecosystems are open systems?
- Absorbs energy and mass, and then release heat and waste products
What are autotrophs?
Organisms that build molecules themselves using photosynthesis or chemosynthesis as an energy source
What is an example of autotrophs?
Plants
What does heterotrophs depend on?
Organisms depend on the biosynthetic output of other organisms;
- do not produce their own food as an energy source
From low of the food chain and high of the food chain, describe who belongs to what
autotrophs –> primary producers
herbivores –> primary consumers
carnivores –> secondary consumers
carnivores eat other carnivores –> tertiary consumers
What are detritivores/decomposers?
Consumers that derive their energy from detritus
What is detritus?
Nonliving organic matter/material
What are some examples of some important detritivores/decomposers? (2)
- prokaryotes
- fungi
What is primary production?
The amount of light energy converted to a chemical energy by autotrophs during a given time period
What are the two autotrophs in the ecosystems?
- autotrophs –> use of photosynthesis
- chemoautotrophs –> use of chemicals
How much of the solar energy goes to photosynthetic organisms?
- Only such a small fraction
What is gross primary production (GPP)?
Total primary production of an ecosystem
What is net primary production (NPP)?
GPP minus energy used by primary producers for respiration
How is GPP measured?
Measured as the conversion of chemical energy from photosynthesis per unit of time
What is NPP only available to?
only to consumers
What is standing crop?
The total biomass of photosynthetic autotrophs at a given time
Which ecosystems are the most productive ecosystems per unit area? (3)
- tropical rain forests
- estuaries
- coral reefs
Which ecosystem is the relatively unproductive per unit area?
Marine ecosystems
What is net ecosystem production (NEP)?
A measure of the total biomass accumulation during a given period
What is the formula of NEP?
GPP minus total respiration of all organisms in an ecosystem
How is NET estimated?
Estimated by comparing the net flux of CO2 and O2 in an ecosystem
What does the release of O2 indicated?
Indicates the storing of CO2
In aquatic ecosystems, what controls primary production? (2)
- light
- nutrients
What is a limiting nutrient?
The element that must be added for production to increase in an area
Which two nutrients usually limit marine production?
- nitrogen
- phosphorous
What is eutrophication?
When an aquatic area receives too much nutrients
- leads to an overgrowth of algae and other microorganisms
What does primary production increase with?
Increases with moisture
What is evapotranspiration?
Water transpired by plants and evaporated from a landscape
What is the most common limiting nutrient in terrestrial ecosystems?
Nitrogen
In terrestrial ecosystems, what is the limiting factor of primary production?
Soil nutrient
What are the various adaptations plants are able to access limiting nutrients from soil? (4)
- Some plants form mutualisms with nitrogen-fixing bacteria
- Many plants form mutualisms with mycorrhizal fungi; these fungi supply plants with phosphorus and other limiting elements
- Roots have root hairs that increase surface area
- Many plants release enzymes that increase the availability of limiting nutrients
What is secondary production?
The amount of chemical energy in food converted to new biomass during a given period of time
What is production efficiency?
The fraction of energy stored in food that is not used for respiration
What is the production efficiency formula?
(Net secondary production * 100%) /
(Assimilation of primary production)
What is trophic efficiency?
Percentage of production transferred from one trophic level to the next
What is the trophic efficiency level range?
Usually 10% but has a range of 5% - 20%
About how much chemical energy is fixed by photosynthesis?
Approximately 0.1% (1/1000) of chemical energy
What does each tier represent in a biomass pyramid?
Represents the dry mass of all organisms in one trophic level
What happens to biomass as you reach higher trophic levels?
The biomass sharply decrease
What is turnover time?
Ratio of standing crop biomass to production
What are biogeochemical cycles?
Nutrient cycles in ecosystems involving biotic and abiotic components
Which gases are in the biogeochemical cycles globally? (4)
- gaseous carbon
- oxygen
- sulfur
- nitrogen
What are the less mobile elements in the biogeochemical cycles? (3)
- phosphorous
- potassium
- calcium
What are the 4 factors that ecologists focus on in studying cycling of water, carbon, nitrogen, and phosphorous?
- Each chemical’s biological importance
- Forms in which each chemical is available or used by organisms
- Major reservoirs for each chemical
- Key processes driving movement of each chemical through its cycle
On earth, how is water distributed?
97% of it is in the ocean
2% is in glaciers and polar ice caps
1% is in lakes, rivers, and groundwater
What processes is water moved by? (5)
- evaporation
- transpiration
- condensation
- precipitation
- movement thru surface and groundwater
What happens in the carbon cycle? (3)
- CO2 is taken up and released through photosynthesis and respiration
- volcanoes and the burning of fossil fuels contribute CO2 to the atmosphere
- Organisms such as animals and humans give off carbon dioxide
What cycles are apart of biogeochemical cycle?
- water cycle
- carbon cycle
- phosphorous cycle
- nitrogen cycle
What are two usable forms of nitrogen?
Ammonia (NH4)
Nitrate (NO3-)
How does nitrogen convert to a usable form?
By becoming fixed via nitrogen fixation by bacteria
What is denitrificaiton?
Conversion of NO3- (nitrate) to N2 (nitrogen)
What is ammonification?
Decomposing of nitrogen to ammonia NH4
What is nitrification?
Decomposition of NH4/ammonia to nitrate (NO3-)
What is the rate of decomposition controlled by? (3)
- temperature
- moisture
- nutrient availability
What affects the rate at which nutrients cycle differently?
- Differing rates of decomposition
What does rapid decomposition result in?
Results in relatively low levels of nutrients in the soil
Decomposition is slow in what kind of muds?
Anaerobic muds
What is nutrient loss in a forest ecosystem controlled by?
Mainly by plants
What are 2 key strategies of restoration ecology?
- bioremediation
- augmentation of ecosystem processes
What is bioremediation?
Use of organisms to detoxify ecosystems
Which organisms are most often used for bioremediation? (3)
- prokaryotes
- fungi
- plants
What is biological augmentation?
The use of organisms to add essential materials to a degraded ecosystem
What is an example of biological augmentation?
nitrogen-fixing plants can increase the available nitrogen in soil
or
the adding of mycorrhizal fungi to help plants access nutrients in the soil
What is the long term objective of restoration?
Returning the ecosystem to its pre-disturbed state
