LI-COR LI-8100A - Using the 8100-104 C for Net Carbon Exchange (NCE)

Theory of Operation
4-11
W
o
Initial value of W Type 1 "H2O"
k
Rate constant (s
-1
)
u
Air flow rate out of the chamber
(mol s
-1
)
c
a
CO
2
mole fraction of air outside
the chamber (mol mol
-1
)
c
s
'
Dilution-corrected CO
2
mole
fraction of air in the soil (mol
mol
-1
)
c
c
'
Dilution-corrected CO
2
mole
fraction of air inside the chamber
(mol mol
-1
)
c
a
'
Dilution-corrected ambient CO
2
concentration
c
c
The number density of CO
2
in
the chamber (mol m
-3
)
c
w
The number density of water
vapor in the chamber (mol m
-3
)
c
The total number density of air in
the chamber (mol m
-3
)
c
a
The number density of dry air in
the chamber (mol m
-3
)
g
Conductance to CO
2
(m s
-1
)
a
Rate Constant (s
-1
)
Exponential Coefficient
Type 3 "CrvFit"
t
0
Time Zero Type 2 "CrvTime"
C' (t)
Dilution-corrected CO
2
(μmol
mol
-1
)
"Cdry"
C'
o
Initial dilution-corrected CO
2
(μmol mol
-1
)
Type 1 "Cdry"
C
x
'
Asymptote parameter from
exponential fit (μmol mol
-1
)
Type 4 "CrvFit"
Using the 8100-104C for Net Carbon Exchange (NCE)
At the ecosystem level, carbon (CO
2
) is fixed through photosynthetic carbon
metabolism, and then fixed carbon is used for growth and development of plants.
Some of the fixed carbon will be lost through respiration. Inside a clear chamber,
Net Carbon Exchange (NCE) is defined as the net carbon exchange between an
ecosystem and the atmosphere, which is the photosynthesis uptake minus the total