Conductance to CO2 (umol / (m^2 s Pa))
Conductance to CO2 (umol / (m^2 s Pa))
- g_tc: total conductance to CO2
- g_uc: cuticular conductance to CO2
- g_bc: boundary layer conductance to CO2
- g_mc: mesophyll conductance to CO2
- g_sc: stomatal conductance to CO2
.get_gtc(pars, unitless) .get_guc(pars, surface, unitless) .get_gbc(pars, surface, unitless) .get_gmc(pars, surface, unitless) .get_gsc(pars, surface, unitless)
pars |
Concatenated parameters ( |
unitless |
Logical. Should |
surface |
Leaf surface (lower or upper) |
Total conductance to CO2 is the sum of parallel conductances on the lower (gc_lower) and upper (gc_upper) leaf portions:
gc_total = gc_lower + gc_upper
Each partial conductance consists of two parallel conductances, the cuticular conductance (g_uc) and the in-series conductances through mesophyll (g_mc), stomata (g_sc), and boundary layer (g_bc). To simplify the formula, I use substitute resistance where r_x = 1 / g_x. For surface i:
g_ci = g_ui + (1 / (r_mi + r_si + r_bi))
The cuticular, stomatal, and mesophyll conductances can be the same or different for upper and lower. The partitioning factors (k_x) divide the conductance between surfaces while keeping the total conductance constant:
gx_lower = g_x (1 / (1 + k_x))
gx_upper = g_x (k_x / (1 + k_x))
g_x = gx_lower + gx_upper
How the partitioning factors work:
| k_x | description |
| 0 | all conductance on lower surface/portion |
| 0.5 | 2/3 conductance on lower surface |
| 1 | conductance evenly divided between surfaces/portions |
| 2 | 2/3 conductance on upper surface |
| Inf | all conductance on upper surface/portion |
The boundary layer conductances for each are calculated on the basis of mass and heat transfer (see .get_gbc).
| Symbol | R | Description | Units | Default |
| g_mc | g_mc |
mesophyll conductance to CO2 (T_leaf) | μmol CO2 / (m^2 s Pa) | calculated |
| g_sc | g_sc |
stomatal conductance to CO2 | μmol CO2 / (m^2 s Pa) | 4 |
| g_uc | g_uc |
cuticular conductance to CO2 | μmol CO2 / (m^2 s Pa) | 0.1 |
| k_mc | k_mc |
partition of g_mc to lower mesophyll | none | 1 |
| k_sc | k_sc |
partition of g_sc to lower surface | none | 1 |
| k_uc | k_uc |
partition of g_uc to lower surface | none | 1 |
Please choose more modern alternatives, such as Google Chrome or Mozilla Firefox.