Chapter 19 Ecology
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Carbon is the currency because
it is stored by autotrophs and transferred to heterotrophs
Gross primary production (GPP)—
total amount of carbon fixed by autotrophs in an ecosystem.
GPP depends on the influence of climate on photosynthetic rate and the leaf area index (LAI)—
leaf area per unit of ground area.
Net primary production (NPP)=
NPP = GPP – respiration
The balance between GPP and respiration;
plant biomass gained NPP is allocated among growth, reproduction, storage, and defense NPP allocated to leaves, stems, and roots depends on resource availability of light, nutrients, water, and carbon NPP allocated to storage compounds is insurance
Important to estimate NPP because:
Source for energy traveling to upper trophic levels Variation provides information on ecosystem change Closely tied to global carbon cycle; carbon moving from atmosphere into ecosystems
Estimating belowground plant biomass (roots) is more difficult:
Roots turnover much more rapidlyRoots transfer carbon to mycorrhizal or bacterial symbiontsMore frequent correction factorsalgorithms that relate above to
Destructive Sampling (impractical over large scale): to measure NPP
- Harvesting aboveground plant biomass before and after the growing seasonScale estimates up to the ecosystem
- Provides a destructive estimate of NPP
Create a closed system and measure CO2 inside tent. The CO2 change is called
Net Ecosystem Exchange (NEE)
Both ----------and-------------- directly affect NPP.
precipitation and temperature
NPP increases with increasing precipitation to a point.....
Declines at higher precipitation because cloud cover limits photosynthesis and rain leaches nutrients from soils.
NPP increases with
NPP in the open ocean is derived from --------and limited by
phytoplankton and is mostly limited by nitrogen
Near the coast, ------------and-------------- contribute to NPP in more shallow areas.
kelp forests and seagrass beds. Equatorial Pacific ocean, nitrogen can be detected in the water
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