Ch 55 Ecosystems Flashcards
Ecosystem size range
Microscopic to large scale
Two main processes in an ecosystem:
1) Energy flow
2) Chemical cycling
___ flows through an ecosystem
Energy
___ cycles within an ecosystem
Matter
1st law of thermodynamics
Energy is neither created nor destroyed, but can be transformed from one form to another
2nd law of thermodynamics
Physical systems tend to proceed to a state of greater disorder (entropy)
Law of conservation of mass
States that matter can be neither created nor destroyed
1)___ elements are continually 2)___ within an ecosystem
1) Chemical
2) Recycled
What kind of system is an ecosystem?
An open system
Open systems absorb:
1) Energy
2) Mass
Open systems release:
1) Heat
2) Waste products
Primary production
The amount of light energy converted into chemical energy by autotrophs in a given time period
The extent of 1)___ ___ sets the spending limit for an 2)___ ___ ___
1) Photosynthetic production
2) Ecosystem’s energy budget
Gross primary production (GPP)
The total primary production of an ecosystem
Gross primary production is measured as what?
The conversion of chemical energy from photosynthesis per unit time
How is net primary production (NPP) calculated?
Gross primary production (GPP) minus energy used by primary producers for respiration
Two ways net primary production (NPP) is expressed:
1) Energy per unit area per unit time (J/m^2*yr)
2) Biomass added per unit area per unit time (g/m^2*yr)
Net primary production (NPP)
The amount of new biomass added in a given time period
Ecosystems vary greatly in what?
Net primary production
Ecosystems contribute to what?
The total net primary production on Earth
Net ecosystem production (NEP)
The total biomass accumulated during a given period
How is net ecosystem production (NEP) calculated?
Gross primary production minus the total respiration of all organisms (consumer + producers) in an ecosystem
Net ecosystem production (NEP) is estimated by comparing what?
The net flux of CO2 and O2 in an ecosystem
In marine and freshwater ecosystems, what controls primary production?
1) Light
2) Nutrients
What two nutrients most often limit marine production?
1) Nitrogen
2) Phosphorus
Eutrophication
The addition of extra nutrients to bodies of water
Results of eutrophication:
1) Algae population explosions
2) Depletion of oxygen from these habitats
Critical load
The amount of added nutrients that can be absorbed by plants without damaging ecosystem integrity
What causes dead zones?
Decomposition of phytoplankton blooms, which create low oxygen levels
In terrestrial ecosystems, what affects primary production on a large scale?
1) Temperature
2) Moisture
In terrestrial ecosystems, what affects primary production on the small scale?
Soil nutrients (nitrogen, etc.)
Secondary production
The amount of chemical energy in food converted to new biomass during a given period of ime
Production efficiency (definition)
The fractions of energy stored in food that is not used for respiration
Production efficiency (equation)
Net secondary production/Assmilation of primary production
Do ectotherms or extotherms have higher production efficiencies?
Ectotherms
Trophic efficiency
The percentage of production transferred from one trophic level to the next
What is trophic efficiency, usually?
~10%
Terrestrial ecosystem biomass pyramid
inefficiency of production transfer between trophic levels leads to a pyramid in the distribution of biomass
In the terrestrial ecosystem biomass pyramid, is there more biomass at higher or lower levels?
Lower levels
In the terrestrial ecosystem biomass pyramid, 1)___ ___ ___ is required to produce biomass at 2___ ___ ___
1) More total energy
2) Higher trophic levels
Do terrestrial or aquatic ecosystems transfer energy more efficiently?
Aquatic ecosystems
Why do aquatic ecosystems transfer energy more efficiently?
1) More cold-blooded (low metabolism) consumers
2) Longer food chains
3) More rapid turnover in primary producers
1)___ primary production, 2)___ standing producer biomass
1) High
2) Low
Gaseous forms of what four elements occur in the atmosphere and cycle globally?
1) Carbon
2) Oxygen
3) Sulfur
4) Nitrogen
All elements cycle between 1)___ and 2)___ reservoirs
1) Organic
2) Inorganic
What kind of elements cycle locally?
Less mobile elements (phosphorus)
When are less mobile elements cycled more broadly?
When they are dissolved in aquatic systems
Only ___ of Earth’s water is available in lakes, streams, and groundwater
1%
What is the main process driving the water cycle?
Evaporation by solar energy
Carbon cycle
Carbon added to the atmosphere is removed
How is carbon added to the atmosphere?
By respiration of living organisms (CO2)
How is carbon removed from the atmosphere?
By photosynthesis
Major reservoirs of carbon:
1) Soil
2) Oceans
3) Biomass
4) Atmosphere
5) Fossil fuel (oil)
Nitrogen cycle
Only plans and bacteria can acquire nitrogen from the atmosphere to make organic molecules from which animals can acquire nitrogen
Phosphorus is a major component of:
1) Nucleic acids
2) Phospholipids
3) ATP
What is the most important inorganic form of phosphorus?
Phosphate (PO4)
Major reservoirs of phosphorus:
1) Sedimentary rocks
2) Ocean
3) Organisms
What heavily dictates the rate at which nutrients cycle?
The rate of decomposition
What controls the rate of decomposition?
1) Temperature
2) Moisture
3) Nutrient availability
Restoration ecology
The study of ways to initiate or speed up the recovery of degraded ecosystems
How does restoration ecology try to restore degraded ecosystems?
Manipulating biogeomechanical signaling
Bioremediation
The use of organisms (bacteria, fungi, plants) to detoxify ecosystems
Biological augmentation
The use of organisms to add essential materials to a degraded ecosystem
