Table 3. Observations of embolized conduits and dimensions from microCT and their simulated impact on Kx using the spatially explicit K_LEAF model.
Because we did not have the resolution to determine whether conduit collapse occurs in tertiary and minor veins, two simulations were performed based on minor vein conduit collapse observed in Quercus rubra (see “Materials and Methods”). Note that two leaves were imaged at each water potential (22 leaves total); embolism at the four water potentials below were only found in one of the two leaves tested at that water potential. Dashes are shown for samples where no embolized conduits were observed, and thus no simulations were performed.
| Ψleaf | No. of Embolized Conduits | Length of Embolized Conduit | Diameter of Embolized Conduit | Simulated Percentage Loss of Xylem Hydraulic Conductance | |||||
|---|---|---|---|---|---|---|---|---|---|
| Midrib | 2° | 3°+ | Midrib | Midrib | 2° | Embolism Only | Embolism + Realistic 3° + Vein Collapse (13% PLC) | Embolism + Severe 3° + Vein Collapse (50% PLC) | |
| MPa | μm | % | |||||||
| −0.06 | 0 | 0 | 0 | – | – | – | 0 | – | – |
| −0.08 | 0 | 0 | 0 | – | – | – | 0 | – | – |
| −0.13 | 1 | 1 | 0 | >898 | 7.3 | 8.7 | 7.13 | 9.99 | 19.1 |
| −0.16 | 0 | 0 | 0 | – | – | – | 0 | – | – |
| −0.18 | 2 | 2 | 0 | 258, >600 | 6.2, 5.3 | 5.2, 3.5 | 3.96 | 6.70 | 16 |
| −0.45 | 0 | 1 | 0 | – | – | 5.2 | 0.96 | 3.12 | 9.1 |
| −0.48 | 1 | 0 | 0 | >850 | 5.9 | – | 1.16 | 3.96 | 13 |
| −0.50 | 0 | 0 | 0 | – | – | – | 0 | – | – |
| −0.69 | 0 | 0 | 0 | – | – | – | 0 | – | – |
| −0.79 | 0 | 0 | 0 | – | – | – | 0 | – | – |
| −0.87 | 0 | 0 | 0 | – | – | – | 0 | 2.82 | 12 |