Appendix A. Effects of the five scenarios on labeled-N fractions in belowground plant biomass.

FIG. A1. Simulation (lines) and actual data (symbols) of the labeled-N fraction in belowground plant biomass during five years after a 0.4 g/m^{2} ^{15}N addition using parameters listed in Table 2. Simulation of the labeled-N fraction in aboveground biomass for (A) scenario 1: plant/microbial competition for N, (B) scenario 2: microbial activity, (C) scenario 3: active soil N, (D) scenario 4: N loss, and (E) N resorption and re-translocation. Each panel shows the actual data of the ambient CO_{2} plots (closed circles) and elevated CO_{2} plots (open circles) and the model simulation of the ambient CO2 plots (solid lines), A runs (dotted lines) and B runs (dashed lines). Panel A also includes the model simulation of the ambient CO_{2} plots with a root turnover time of seven years (dash-dot line). Inserted are the goodness of fit G values calculated for the simulations of the labeled-N fraction in belowground plant biomass. |