Figure 1.
Standardized major axis regression (solid lines) for relative resorption efficiency (NRE - PRE) vs green-leaf N:P ratio for (a) all species, black lines; (b) deciduous broadleaf species (DB), brown dots and lines; (c) evergreen broadleaf (EB), green dots and lines; (d) conifers and N-fixing species, respectively blue and red dots and lines.
The horizontal dash lines indicate where NRE equals PRE, and the vertical dash lines display the corresponding N:P ratios.
Figure 2.
Standardized major axis regression for N or P resorption efficiency (NRE or PRE, NuRE) vs green-leaf N:P ratio for (a) all species; (b) deciduous broadleaf species (DB); (c) evergreen broadleaf species (EB); and (d) conifers.
The blue symbols and lines denote NRE, and the red ones represent PRE. Regression lines of NRE vs N:P are not shown in panel (c) and (d) for lack of significant correlations between the two variables in EB and conifers (p = 0.76 and 0.27, respectively).
Figure 3.
Standardized major axis regression (solid lines) for log10-transfromed N:P ratio in senesced against green leaves of (a) all species, (b) deciduous (DB) and (c) evergreen (EB) angiosperms, and (d) conifers.
The dash lines denote the 1:1 lines, above and below which the numbers of data points are shown.
Figure 4.
Relationship between senesced-leaf N/P (uncorrected, in log-scale) and green-leaf N:P ratio.
The three zones (I/II/III, delimitated by horizontal red lines) of senesced-leaf N and P [4] are: < 7 mg g-1 (zone I, complete resorption) and > 10 mg g-1 (zone III, incomplete resorption) for N (a); < 0.5 mg g-1 or < 0.4 mg g-1 (zone I, complete resorption for deciduous and evergreen species, respectively) and > 0.8 mg g-1 or > 0.5 mg g-1 (zone III, incomplete resorption for deciduous and evergreen species, respectively) for P (b). Zones II are intermediate resorption ranges in both panels. The red and green points and Roman numbers indicate the data and zones for deciduous and evergreen species, respectively. The blue points denoting conifers were also shown.
Figure 5.
Figure 5. Standardized major axis regression (solid lines) for the relative resorption efficiency (NRE - PRE) vs. green-leaf N:P ratio across different vegetation-types globally.
Data of boreal and temperate forests in China come from the authors’ unpublished data.