ch 5 Flashcards
what is water use efficiency wue
a measure of how well plants use water relative to photosynthesis, expressed as mmol of CO2 fixed per mmol of water lost.
-Rising CO2 levels in the atmosphere can increase WUE by allowing photosynthesis to occur at lower stomatal conductance
how to find NPP?
gross primary production minus plant respiration equals net primary production (Gross primary production - plant respiration = net primary production).
how to calculate NEP
NEP = NPP - Rh - Rd; Rh: Rh is the respiration of herbivores, and Rd is the respiration of decomposers.
-net gain or loss of carbon in the ecosystem
what is eddy covariance study
measure co2 concentrations and vertical wind velocity
explain NEP
net accumulation of organic matter in an ecosystem; mostly in wood or soil
name two ways carbon is returned to the atmo
- herbivores
- fires
how do satellites estimated GPP
relies on the differential absorption of light by chlorophyll and other leaf pigments - measure surface reflectance
estimated global NPP measurement
60 billion metric tons, based on MODIS
explain fires and CO2
land clearing by humans is increasing co2 emissions, contributing to climate change and increasing fire occurrences
explain plant growth and co2 impact
co2 concentration enhances the reactant for photosynthesis, increased growth with higher co2, might depend on external factors
what happens to most NPP
directed to the soil as dead organic matter - about hallf of global NPP is below ground
what contributes significantly to soil detritus in most areas
annual growth and death of fine roots
what is a common way to study surface decomposition
litterbag approach, fresh litter in mesh bags periodically replaces and collected for measurements of decomposition rates
