Issues in scaling tree size and age responses to ozone: A review
Issues in scaling tree size and age responses to ozone: A review
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DOI：
10.1016/s0269-7491(97)00132-2
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发表时间：
1997-01-01
影响因子：
8.9
通讯作者：
Skelly, JM
中科院分区：
文献类型：
--
作者：
Kolb, TE;Fredericksen, TS;Skelly, JM
臭氧可能是目前影响森林树木的最重要的区域空气污染物。关于臭氧对植物影响的绝大多数信息来自于对幼苗的实验，在实验中，在室内或室外室中控制臭氧浓度，持续时间从几天到一个或多个生长季节。然而，很难将幼苗实验的结果外推或扩展到更大的林木。成熟的树木通常不同于幼苗的形态，物候和生理特征，可能会深刻影响臭氧暴露的反应。此外，与森林树冠层内的接触相比，在地面附近生长的幼苗的臭氧接触动态可能有所不同。对臭氧敏感性的不同解释使从幼苗到树冠树木的臭氧反应能力复杂化。成熟树木和幼苗之间的臭氧敏感性差异可能是因为以下方面的差异：臭氧吸收（避免），对受损组织的补偿，反对组织损伤（防御）的内部属性，以及组织损伤的修复。在这些机制中，回避通常在缩放研究中测量，而补偿，防御和修复则没有。对不同大小和年龄的树木气孔导度的比较研究表明，大树的气孔导度通常低于幼苗，这表明大树更能避免臭氧吸收，但这种明显的趋势也有明显的例外。对于树种的响应，臭氧和气孔导度之间的大型和小型树木进行了比较，最大的气孔导度的树的大小类表现出最大的不利叶臭氧的生理反应。这一发现支持了这一假设，即不同大小的自由的相同物种之间的臭氧反应的差异发生，至少在一定程度上，因为在臭氧吸收的差异。对于大多数这些物种（云杉，黄松，李，红杉），大或老的树木有较低的气孔导度和较低的臭氧叶片伤害比小或年轻的树木，而对于红栎，大树有较大的气孔导度和较大的臭氧叶片伤害比小树。从已发表的缩放研究中得出明确的结论是复杂的，因为研究方法和“幼苗”和“成熟树”的定义存在很大差异。为了促进臭氧对树木影响的综合和改进预测，Mie建议，未来的臭氧缩放研究应采用一套生态和生理特征不同的物种的一致方法，检查不同大小树木的避免、补偿、防御和修复的发生和有效性。我们还建议，未来的研究检查这些机制的可能后果，以长期的生态成功的不同大小的树木在其他生物和非生物压力的存在，（C）1998爱思唯尔科学有限公司保留所有权利。
Ozone is probably the most important regional air pollutant currently affecting forest trees. The vast majority of information regarding ozone effects on frees has come from experiments with seedlings, where controlled concentrations of ozone were administered in indoor ol outdoor chambers for periods lasting from several clays to one ol more growing seasons. However, it is difficult to extrapolate, or scale, results from experiments on seedlings to larger forest trees. Mature trees typically differ from seedlings in morphological, phenological, and physiological characteristics that may profoundly influence response to ozone exposure. Also, it is possible that ozone exposure dynamics may differ for seedlings growing near the ground compared to exposure within the forest canopy. Complicating the ability to scale ozone responses from seedlings to canopy trees are differing interpretations of what is meant by ozone sensitivity. Differences in ozone sensitivity between mature trees and seedlings may occur because of differences in: ozone uptake (avoidance), compensation for injured tissues, internal properties that oppose the production of tissue injury (defense), and repair of tissue injury. Of these mechanisms, avoidance is commonly measured in scaling studies whereas compensation, defense, and repair are not. A review of studies that have compared stomatal conductance between trees of different size and age showed that large trees typically, have lower stomatal conductance than seedlings, suggesting greater avoidance of ozone uptake by lar ge trees, but there are notable exceptions to this apparent trend. For tree species where response to ozone and stomatal conductance has been compared between large and small trees, the tree size class with the greatest stomatal conductance showed the greatest detrimental leaf physiological response to ozone. This finding supports the hypothesis that differences in ozone response between different-sized frees of the same species occurs, at least in part, because of differences in ozone uptake. For most of these species (Picea rubens, Pinus ponderosa, Prunus serotina, Sequoiadendron giganteum), large or old trees had lower stomatal conductance and lower ozone foliar injury than small or young trees, whereas for Quercus rubra, large trees had greater stomatal conductance and greater ozone foliar injury than small trees. Drawing firm conclusions from published scaling studies is complicated by wide variation in study methodology and how 'seedling' and 'mature tree' are defined. To facilitate synthesis and improve prediction of ozone impacts on trees, Mie recommend that future ozone scaling research examine the occurrence and effectiveness of avoidance, compensation, defense, and repair in trees of different sizes with consistent methodology on a suite of species that vary in ecological and physiological characteristics. We also recommend that future research examine the possible consequences of these mechanisms to long-term ecological success for trees of different sizes in the presence of other biotic and abiotic stresses, (C) 1998 Elsevier Science Ltd. All rights reserved.