GOTILWA: An Integrated Model of Water Dynamics and Forest Growth
171
350 ppm atmospheric CO2• These corrections are only used in climate change
simulations.
Absorbed C02 is converted into organic matter (OM) using:
GPPi = U C02 • 0.012·2.1 ,
where Uco is the carbon uptake (mmo!), the factor 0.012 transforms the
moles of drbon into grams, and 2.1 is the proportion of OM to C which is
considered as a constant value (see Table 12.2)
12.3.8 Leaf Respiration
The respiration of any component of the plant is temperature-dependent.
The role of temperature is introduced in GOTILWA using the QJO function
estimated as:
Tm -20
QlO,t = QIO,20- IO-,
where T m is the mean temperature of the month. The final respiration rate
depends on the fraction of mobile carbon present in the leaf. This fraction
has a base respiration rate of 55.5 cal g-I DM day-I while the structural components have a base respiration rate of 33.3 cal g-I DM day-I, so the respiration of the leaf tissues is:
Rl = 55.5 . Cm . QlO,t + 33.3 . (1 - Cm) . QIO,t ,
where Rl is the leaf respiration rate, Cm is the fraction of mobile carbon in
leaves and QlO,t is the value of QIO at temperature t.
12.3.9 Wood Respiration
Similarly, the living woody tissues depend on the QIO value and the base respiration rate, which has been estimated as 35 cal g-I DM year-I. The fraction
of living xylem is a constant fraction of sapwood.
12.3.10 Fine Root Respiration
Fine root dynamics seems to parallel leaf dynamics in most ecosystems in
which both have been analyzed (Kummerow and Ellis 1989). GOTILWA assumes that fine root biomass is a constant fraction of leaf biomass. Any
variations in leaf area or leaf biomass can be translated into a proportional
variation in fine root biomass.
171
350 ppm atmospheric CO2• These corrections are only used in climate change
simulations.
Absorbed C02 is converted into organic matter (OM) using:
GPPi = U C02 • 0.012·2.1 ,
where Uco is the carbon uptake (mmo!), the factor 0.012 transforms the
moles of drbon into grams, and 2.1 is the proportion of OM to C which is
considered as a constant value (see Table 12.2)
12.3.8 Leaf Respiration
The respiration of any component of the plant is temperature-dependent.
The role of temperature is introduced in GOTILWA using the QJO function
estimated as:
Tm -20
QlO,t = QIO,20- IO-,
where T m is the mean temperature of the month. The final respiration rate
depends on the fraction of mobile carbon present in the leaf. This fraction
has a base respiration rate of 55.5 cal g-I DM day-I while the structural components have a base respiration rate of 33.3 cal g-I DM day-I, so the respiration of the leaf tissues is:
Rl = 55.5 . Cm . QlO,t + 33.3 . (1 - Cm) . QIO,t ,
where Rl is the leaf respiration rate, Cm is the fraction of mobile carbon in
leaves and QlO,t is the value of QIO at temperature t.
12.3.9 Wood Respiration
Similarly, the living woody tissues depend on the QIO value and the base respiration rate, which has been estimated as 35 cal g-I DM year-I. The fraction
of living xylem is a constant fraction of sapwood.
12.3.10 Fine Root Respiration
Fine root dynamics seems to parallel leaf dynamics in most ecosystems in
which both have been analyzed (Kummerow and Ellis 1989). GOTILWA assumes that fine root biomass is a constant fraction of leaf biomass. Any
variations in leaf area or leaf biomass can be translated into a proportional
variation in fine root biomass.