高浓度O3对城市蒙古栎凋落叶分解和养分释放的影响

采用开顶箱(OTCs)模拟法和分解袋法，以O₃自然浓度(40 nmol·mol^-1)为对照，研究高浓度O₃(约120 nmol·mol^-1)对城市自然环境下生长的10年生蒙古栎凋落叶分解和养分释放的影响，分解时长达150 d.结果表明：高浓度O₃未对蒙古栎凋落叶的分解产生显著影响.高浓度O₃抑制了蒙古栎凋落叶C、K释放，分解150 d，高浓度O₃处理K残留率为23.9%，显著高于对照(17.1%).高浓度O₃在分解前期(0～60 d)抑制了凋落叶N、木质素的释放，在分解后期(60～150 d)起促进作用.高浓度O₃处理与对照木质素/N变化趋势一致且无显著差异.除分解中期(60 d)外，对照P残留率始终高于高浓度O₃处理.C/P变化趋势与P相反，在整个分解过程中，高浓度O₃处理C/P高于对照，而且C、N、K残留率以及C/N与凋落叶干质量剩余率呈显著正相关.因此，高浓度O₃将对蒙古栎林的营养循环产生一定影响.

Effects of elevated O3 on leaf litter decomposition and nutrient release of Quercus mongolica in city.

The leaf litters of 10-year-old Quercus mongolica were put in nylon bags and exposed to elevated O₃ level (120 nmol·mol^-1) with the control of 40 nmol·mol-1 in open top chambers (OTCs) for 150 days to test the effect of high O₃ on the litter decomposition. The results showed that no significant difference was observed in residual mass between elevated O₃ treatment and the control. Elevated O₃ inhibited the release of C and K during the decomposition, the residual rate of K under elevated O_3treatment (23.9%) was significantly higher than that of the control (17.1%) after 150 day decomposition. Compared with the control, N mineralization and lignin degradation in elevated O₃ treatment were inhibited during early period of decomposition (0-60 d), but were promoted in later period (90-150 d). The changes of lignin/N showed no significant difference between elevated O₃ treatment and the control during the decomposition. Elevated O₃ generally promoted the release of P in leaf litter of Q. mongolica during the decomposition. C/P ratio was higher under elevated O₃ than that under control. Significant positive correlation was shown between residual dry mass of leaf litters and the residual rate of C, N, K, C/N ratio during decomposition. Elevated O₃ might play an important role in the nutrient cycle of forest ecosystem in high O₃ pollution area.