Interactive influences of ozone and climate on streamflow of forested watersheds
Interactive influences of ozone and climate on streamflow of forested watersheds
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DOI：
10.1111/j.1365-2486.2012.02787.x
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发表时间：
2012-11-01
影响因子：
11.6
通讯作者：
Pederson, Neil
中科院分区：
文献类型：
--
作者：
Sun, Ge;McLaughlin, Samuel B.;Pederson, Neil
对流层臭氧会损害光合作用和植物蒸腾作用的气孔控制，从而影响生态系统生产力和流域水文，从而对森林减缓全球气候变化的能力产生不利影响。我们已经评估了位于美国东南部的6个森林流域（38-970 000公顷）的臭氧和气候对晚季径流的单独和相互作用的影响。模型的基础上，18-26年的数据记录，每个流域，并涉及多变量分析的年际变化的晚季径流在生长季节的物理和化学气候。在所有情况下，臭氧变量的某种组合大大提高了模型的性能，超过了只考虑气候的模型。臭氧的影响以及臭氧与气候的相互作用也一直是负面的，并且与实际臭氧暴露的变化成比例，无论是在整个区域的空间上还是在一段时间内。臭氧对观测流量的变异性（R2）的影响的保守估计范围从西弗吉尼亚州臭氧暴露量最低的地区的7%到田纳西州臭氧暴露量最高的地区的23%。我们的研究结果得到了支持的控制现场研究使用自由空气浓度富集的方法，这表明渐进的臭氧引起的损失气孔控制树蒸腾在夏季混合白杨白桦林。尽管经常假设臭氧减少树木水分流失，我们的研究结果支持越来越多的证据表明，臭氧在接近环境浓度可以减少气孔控制叶片蒸腾，增加用水。由于环境臭氧暴露而引起的蒸散量增加和相关的径流量减少，预计将间歇性地增加干旱的频率和严重程度，并影响森林流域中依赖水流的水生生物群。水文循环和相关生态系统功能的区域和全球模型应考虑在当前和未来较暖和臭氧富集的气候条件下臭氧与气候的潜在相互作用。
The capacity of forests to mitigate global climate change can be negatively influenced by tropospheric ozone that impairs both photosynthesis and stomatal control of plant transpiration, thus affecting ecosystem productivity and watershed hydrology. We have evaluated individual and interactive effects of ozone and climate on late season streamflow for six forested watersheds (38-970 000ha) located in the Southeastern United States. Models were based on 18-26 year data records for each watershed and involved multivariate analysis of interannual variability of late season streamflow in response to physical and chemical climate during the growing season. In all cases, some combination of ozone variables significantly improved model performance over climate-only models. Effects of ozone and ozone xclimate interactions were also consistently negative and were proportional to variations in actual ozone exposures, both spatially across the region and over time. Conservative estimates of the influence of ozone on the variability (R2) of observed flow ranged from 7% in the area of lowest ozone exposure in West Virginia to 23% in the areas of highest exposure in Tennessee. Our results are supported by a controlled field study using free-air concentration enrichment methodology which indicated progressive ozone-induced loss of stomatal control over tree transpiration during the summer in mixed aspen-birch stands. Despite the frequent assumption that ozone reduces tree water loss, our findings support increasing evidence that ozone at near ambient concentrations can reduce stomatal control of leaf transpiration, and increase water use. Increases in evapotranspiration and associated streamflow reductions in response to ambient ozone exposures are expected to episodically increase the frequency and severity of drought and affect flow-dependent aquatic biota in forested watersheds. Regional and global models of hydrologic cycles and related ecosystem functions should consider potential interactions of ozone with climate under both current and future warmer and ozone-enriched climatic conditions.