| 180 | | MENTION 2 OPTIONS |
| 181 | | |
| 182 | | PHI_LEAF_xx |
| 183 | | PHI_50_xx |
| 184 | | K_SAP_xx |
| 185 | | K_ROOT_xx |
| 186 | | K_LEAF_xx |
| 187 | | PHI_SOIL_TUNE_xx |
| 188 | | |
| | 180 | With ORCHIDEE-CN-CAN there is two option to calculate waters stress. |
| | 181 | |
| | 182 | 1 - Same as in the trunk, where a soil moisture stress functions limits C assimilation through constraints on the carboxylation capacity. |
| | 183 | |
| | 184 | 2 - The second possibility takes hydraulic architecture of plants into account, when calculating the plant water supply. This scheme, based on Hickler et al (2006), calculates the water supply as the ratio of the pressure difference between the soil and leaves. The plant water supply is the amount of water the plant can transport from the soil to the stomate accounting for resistance of water transport in the roots, sapwood and leaves. The resistances are inversely proportional to the conductivities in these different tissues, with the sapwood conductivity decreasing when cavitations occurs. If transpiration rates exceeds plant water supply, stomatal conductance is reduced. |
| | 185 | |
| | 186 | If you wish to make simulations with the hydraulic architecture the CWRR hydrology scheme needs to be activated ('''HYDROL_CWRR'''=y). Moreover, both '''mleb''' and '''ok_hydrol_arch''' needs to be true. These can be controlled by the overall flag '''multi_layer_control''' (see section on Single layer vs. multi-layer energy budget for more elaboration on these flags). |
| | 187 | |
| | 188 | The following PFT dependent parameters are needed for the calculations accounting for plant hydraulic architecture; minimal leaf water potential '''PHI_LEAF_xx''', sapwood leaf water potential that causes 50 % loss of xylem '''PHI_50_xx''', additive tuning parameter to account for soil-root interactions '''PHI_SOIL_TUNE_xx''', maximum sapwood conductivity '''K_SAP_xx''', root conductivity '''K_ROOT_xx''', leaf conductivity '''K_LEAF_xx'''. |
