Table 3.
The scaling coefficients of xylem and phloem properties as a function of stem/branch diameter used in the scaling Equation (1).
| Scaling coefficient | Symbol | Value used for pine | Value used for aspen | Measured/estimated from literature* |
|---|---|---|---|---|
| Base for stem/branch diameter as a function of distance from leaf apex (mm) | γ | 15.8 mm | 15.6 mm | Measured |
| Base for xylem cross-sectional area as a function of stem/branch diameter | α1 | 0.82 | 0.71 | Measured |
| Base for phloem cross-sectional area as a function of stem/branch diameter | α2 | 0.75 | 0.99 | Measured |
| Base for xylem nitrogen concentration as a function of stem/branch diameter | α3 | 2.02 | 0.68 | Measured |
| Base for phloem nitrogen concentration as a function of stem/branch diameter | α4 | 1.4 | 22.1 | Measured |
| Base for xylem conduit radius as a function of stem/branch diameter | α5 | 1 unit less | 1 unit less | Irrelevant as only relative values are shown |
| Base for phloem conduit radius as a function of stem/branch diameter | α6 | 1 unit less | 1 unit less | Irrelevant as only relative values are shown |
| Base for xylem conduit density (ratio of conduit cross-sectional area to tissue cross-section area) as a function of stem/branch diameter | α7 | 1 unit less | 1 unit less | Irrelevant as only relative values are shown |
| Base for phloem conduit density (ratio of conduit cross-sectional area to tissue cross-section area) as a function of stem/branch diameter | α8 | 1 unit less | 1 unit less | Irrelevant as only relative values are shown |
| Exponent for stem/branch diameter as a function of distance from leaf apex | δ | 0.97 | 0.97 | Measured |
| Exponent for xylem cross-sectional area as a function of stem/branch diameter | β1 | 1.98 | 2.00 | Measured |
| Exponent for phloem cross-sectional area as a function of stem/branch diameter | β2 | 1.27 | 1.31 | Measured |
| Exponent for xylem nitrogen concentration as a function of stem/branch diameter | β3 | −0.61 | −0.34 | Measured |
| Exponent for phloem nitrogen concentration as a function of stem/branch diameter | β4 | −0.22 | −0.80 | Measured |
| Exponent for xylem conduit radius as a function of stem/branch diameter | β5 | 0.25 | 0.25 | West et al., 1999 |
| Exponent for phloem conduit radius as a function of stem/branch diameter | β6 | 0.25 | 0.25 | West et al., 1999; Jensen et al., 2011; Mencuccini et al., 2011 |
| Exponent for xylem conduit density (ratio of conduit cross-sectional area to tissue cross-section area)as a function of stem/branch diameter | β7 | 0 | 0 | Savage et al., 2010 |
| Exponent for phloem conduit density (ratio of conduit cross-sectional area to tissue cross-section area) as a function of stem/branch diameter | β8 | 0 | 0 | Assumed to be the same as for the xylem |
| Leaf to sapwood area ratio Cls | Cls | 3400 m2/m2 | 2700 m2/m2 | Hoffmann and Usoltsev, 2002; Martinez-Vilalta et al., 2009 |
| Specific leaf area | ρSLA | 300 g/m2 | 80 g/m2 | Niinemets, 1997; Martinez-Vilalta et al., 2009 |
| Leaf nitrogen content | ρN, leaf | 1.2% | 2.4% | Niinemets, 1997; Martinez-Vilalta et al., 2009 |
Stem/branch diameter (d) is in units of millimeters (mm).