Fig. 4.

Mechanisms which drive species differences in plant nitrogen pool size. (A) Ecosystem level nitrogen inputs (III), change in total plot nitrogen over 6 years (g N/m²); (B) Ecosystem level nitrogen losses (IV), nitrogen leaching losses over one growing season (g N/m²); (C) Soil nitrogen turnover rate (V), seasonal average of gross nitrogen mineralization (mg NH₄-N/kg soil day); (D) Plant nitrogen turnover rate (VI), nitrogen residence time (Years). Species differences in plant and soil response variables were examined using one-way ANOVA; letters represent significant differences across species from post hoc Tukey tests (P < 0.05). For species abbreviations, see Fig. 2. Roman numerals refer to the framework in Fig. 1.