Abstract
There are very few studies about the effects of relatively higher CO(2) concentration (e.g., 1000 μmol·mol(-1)) or plus N fertilization on woody plants. In this study, Schima superba seedings were exposed to ambient or eCO(2) (550, 750, and 1000 μmol·mol(-1)) and N fertilization (0 and 10 g·m(-2)·yr(-1), hereafter: low N, high N, respectively) for one growth season to explore the potential responses in a subtropical site with low soil N availability. N fertilization strongly increased leaf mass-based N by 118.38%, 116.68%, 106.78%, and 138.95%, respectively, in different CO(2) treatments and decreased starch, with a half reduction in leaf C:N ratio. Leaf N was significantly decreased by eCO(2) in both low N and high N treatments, and N fertilization stimulated the decrease of leaf N and mitigated the increase of leaf C:N by eCO(2). In low N treatments, photosynthetic rate (Pn) was maximized at 733 μmol·mol(-1) CO(2) in August and September, while, in high N treatments, Pn was continuously increased with elevation of CO(2). N fertilization significantly increased plant biomass especially at highly elevated CO(2), although no response of biomass to eCO(2) alone. These findings indicated that N fertilization would modify the response of S. superba to eCO(2).