Stomatal uptake of O3 in a Schima superba plantation in subtropical China derived from sap flow measurements.
Stomatal uptake of O3 in a Schima superba plantation in subtropical China derived from sap flow measurements.
复制标题
DOI：
10.1016/j.scitotenv.2015.12.122
复制
发表时间：
2016-03
期刊：
影响因子：
--
通讯作者：
J. Niu;P. Zhao;Zhenwei Sun;Liwei Zhu;G. Ni;X. Zeng;Zhenzhen Zhang;Xiuhua Zhao;Peiqiang Zhao;Jianguo Gao;Yanting Hu;Xiaomin Zeng;L. Ouyang
中科院分区：
文献类型：
--
作者：
J. Niu;P. Zhao;Zhenwei Sun;Liwei Zhu;G. Ni;X. Zeng;Zhenzhen Zhang;Xiuhua Zhao;Peiqiang Zhao;Jianguo Gao;Yanting Hu;Xiaomin Zeng;L. Ouyang
木荷是中国亚热带生态和经济上重要的常绿先锋树种，其人工林的冠层气孔臭氧 (O3) 通量 (Fst,O3) 通过两年期间的液流测量进行了量化。 4 月至 9 月雨季的平均 Fst,O3 和累积 Fst,O3(AFst0) 显着高于 10 月至 3 月的旱季（分别为 3.90 nmol m−2s−1 和 24.15 mmol m−1）（分别为 4.62 nmol m−2s−1 和 35.37 mmol m−1），但在 2 年之间具有可比性。实验中，2013年4月至2014年3月分别为4.23 nmol m−2s−1和58.23 mmol m−2，2014年4月至2015年3月分别为4.29 nmol m−2s−1和60.80 mmol m−2。在昼夜尺度上，Fst,O3一般在下午早些时候到中午（13:00-15:00）达到峰值，而最大气孔导度（Gst,O3）通常出现在上午中晚（09:00-11:00）。尽管累积 O3 暴露量 (SUM0) 在 10 月份最高，但月度综合 AFst0 在 7 月份达到最大值。无论是季节性还是年度，累积的 O3 剂量，无论是基于暴露还是基于通量，都明显超过了目前采用的保护林木的临界阈值。这些结果一方面证明了气孔对O3的吸收与其环境暴露水平之间的脱钩；另一方面，表明了S潜在的O3风险。超级班实验场地。因此，本研究认可使用液流测量作为估计 Fst,O3 的可行工具，以及从基于暴露的指标过渡到基于通量的指标来评估林木的 O3 风险。迫切需要进一步研究将气孔 O3 吸收剂量与树木生长减少联系起来，以更好地了解 O3 在自然条件下对树木的影响。
Canopy stomatal ozone (O3) flux (Fst,O3) in a plantation ofSchima superba, an ecologically and economically important evergreen pioneer tree species in subtropical China, was quantified based on sap flow measurements during a 2-year period. MeanFst,O3and accumulatedFst,O3(AFst0) were significantly higher in wet seasons from April to September (4.62 nmol m− 2s− 1and 35.37 mmol m− 2, respectively) than in dry seasons from October to March (3.90 nmol m− 2s− 1and 24.15 mmol m− 1, respectively), yet comparable between the 2 years of the experiment, being 4.23 nmol m− 2s− 1and 58.23 mmol m− 2in April 2013–March 2014 and 4.29 nmol m− 2s− 1and 60.80 mmol m− 2in April 2014–March 2015, respectively. At the diurnal scale,Fst,O3generally peaked in the early to middle afternoon hours (13:00–15:00), while the maximum stomatal conductance (Gst,O3) typically occurred in the middle to late morning hours (09:00–11:00). Monthly integratedAFst0 reached the maximum in July, although accumulated O3exposure (SUM0) was highest in October. Seasonally or yearly, the accumulated O3doses, either exposure-based or flux-based, notably exceeded the currently adopted critical thresholds for the protection of forest trees. These results, on the one hand, demonstrated the decoupling between the stomatal uptake of O3and its environmental exposure level; on the other hand, indicated the potential O3risk forS. superbain the experimental site. Therefore, the present study endorses the use of sap flow measurements as a feasible tool for estimatingFst,O3, and the transition from the exposure-based toward flux-based metrics for assessing O3risk for forest trees. Further studies are urgently needed to relate stomatal O3uptake doses with tree growth reductions for an improved understanding of O3effects on trees under natural conditions.