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Study on the Evaluation of the Abilities for Protection Against the Ultraviolet B Radiation in the Forest Tree Species.

林木树种抗紫外线B辐射能力评价研究。

基本信息

批准号：
09660159
负责人：
MUKAI Yuzuru
金额：
$ 2.3万
依托单位：
Shizuoka University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1997
资助国家：
日本
起止时间：
1997 至 1999
项目状态：
已结题

项目摘要

Increases in solar UV-B (ultraviolet-B radiation, here taken as 290-315 nm) are expected to result from stratospheric ozone depletion. In this study, the effects of UV-B on physiological responses in forest tree species were examined. We constructed novel UV-B radiation system, which can control the dose of supplemental UV-B in proportion to ambient UV-B. The level of UV-B enhancement was up to 1.3 times that in ambient UV-B. The photosynthetic capacities, such gas exchanges and PS II photochemical efficiency, the composition of photosynthetic pigments and UV-B absorbing compound, the activities of the enzymes in the active oxygen-scavenging system were also examined.Because forest trees are exposed to UV-B radiation on long term basis, the increase of UV-B are likely affected to the productivity in artificial forests and species composition in natural forests.Sugi (Cryptomeria japonica)is one of the most important coniferous species in Japan. The area of sugi plantations occupies appr … More oximately 45% of all the artificial forest. In order to assess the affect of the increased UV-B in the productivity of artificial forest, we designed three levels in UV-B radiation in the nursery. Those were, enhanced UV-B treatments using an UV-B radiation system different, decreased level of UV-B using the UV-cutting films, and ambient level of UV-B. The physiological responses of sugi saplings were examined. While the sugi saplings grown in the decreased UV-B level showed slightly increasing in the photosynthetic rate and PS II photochemical efficiency (Fv/Fm), no significant changes were observed between the saplings in the enhanced UV-B and that in the ambient UV-B.In order to understand the influence of the increased UV-B on the species composition in natural forest, we investigate the physiological responses of the five tree species grown in the natural beech (Fagus crenata) forest Mt. Naeba-san. The five species were treated with different UV-B levels using UV-B cutting films. In addition, the seedlings grown in the naturally occurred different UV-B levels were also examined. While the beech seedlings grown in the decreased UV-B level showed significant decrease in the UV-B absorbing compounds compared with that in the ambient level, the seedlings exposed the strong light, which may include high level of UV-B, showed the increase in the UV-B absorbing pigments. Some changes were observed in the chlorophyll contents, chlorophyll a/b ratio, and the pool size of xanthophyll cycle pigments. Since the preliminary experiment using the growth chambers equipped with UV-B radiation system showed the rapid accumulation of the UV-B absorbing pigments in the beech seedlings, the difference observed in the UV-B absorbing pigments was attributed to be adaptation to the UV-B levels where the seedlings were growing. Therefore, beech seedlings growing in the field seemed to have the abilities to accumulate the UV-absorbing pigments in response to the UV-B levels. However, the differences in the timing of the leaf senescence were observed in the seedlings treated with different UV-B levels. Timing of the leaf senescence was earlier in the seedlings treated with high UV-B level. Although the maximum PS II photochemical efficiency were not significantly changed among the five species, the maximum amount of UV-B absorbing pigments were observed. While the differences in the PS II photochemical efficiency between the different UV-B levels within species were not significantly changed among the five species, differences in the range, of the amounts of UV-absorbing pigments between the different UV-B levels within species were observed.These results suggest that the forest tree species have enough abilities to protect against the increase In instant solar UV-B radiation. In the deciduous tree species, such as beech, however, the shortening of the productive period may decrease the annual productivity when the solar UV-B will be increased. Less

太阳 UV-B（紫外线 B 辐射，此处取 290-315 nm）的增加预计是由于平流层臭氧消耗造成的。在本研究中，研究了 UV-B 对森林树种生理反应的影响。我们构建了新型 UV-B 辐射系统，可以根据环境 UV-B 的比例控制补充 UV-B 的剂量。 UV-B 增强水平高达环境 UV-B 的 1.3 倍。还检测了光合能力、气体交换和 PS II 光化学效率、光合色素和 UV-B 吸收化合物的组成、活性氧清除系统中酶的活性。由于林木长期暴露在 UV-B 辐射下，UV-B 的增加可能会影响人工林的生产力和自然物种组成。森林。杉树（Cryptomeria japonica）是日本最重要的针叶树种之一。杉树种植园面积约占人工林面积的 45%。为了评估UV-B增加对人工林生产力的影响，我们在苗圃中设计了三个UV-B辐射水平。这些是，使用不同的 UV-B 辐射系统增强 UV-B 处理，使用 UV 截止膜降低 UV-B 水平，以及环境中的 UV-B 水平。研究了杉树幼苗的生理反应。虽然在降低的 UV-B 水平下生长的杉树幼苗的光合速率和 PS II 光化学效率（Fv/Fm）略有增加，但在增强的 UV-B 水平和环境 UV-B 水平下生长的杉树树苗之间没有观察到显着的变化。为了了解增加的 UV-B 对天然林物种组成的影响，我们研究了生长在天然山毛榉中的 5 种树种的生理反应 (Fagus crenata) 森林苗场山。使用 UV-B 切割膜对这五个物种进行了不同 UV-B 级别的处理。此外，还对自然发生的不同UV-B水平下生长的幼苗进行了检查。虽然在UV-B水平降低的情况下生长的山毛榉幼苗的UV-B吸收化合物与环境水平相比显着减少，但暴露在可能包含高水平UV-B的强光下的幼苗显示出UV-B吸收色素的增加。叶绿素含量、叶绿素 a/b 比和叶黄素循环色素库大小发生了一些变化。由于使用配备 UV-B 辐射系统的生长室进行的初步实验显示，山毛榉幼苗中 UV-B 吸收色素快速积累，因此在 UV-B 吸收色素中观察到的差异归因于幼苗生长时对 UV-B 水平的适应。因此，在田间生长的山毛榉幼苗似乎能够积累吸收紫外线的色素以响应 UV-B 水平。然而，在不同 UV-B 水平处理的幼苗中观察到叶片衰老时间的差异。经过高 UV-B 水平处理的幼苗，叶子衰老的时间较早。尽管五个物种的最大 PS II 光化学效率没有显着变化，但观察到了 UV-B 吸收颜料的最大量。虽然物种内不同 UV-B 水平之间的 PS II 光化学效率差异在 5 个物种中没有显着变化，但观察到物种内不同 UV-B 水平之间的紫外线吸收色素的范围和数量存在差异。这些结果表明，森林树种具有足够的能力来抵御瞬间太阳 UV-B 辐射的增加。然而，对于落叶树种，如山毛榉，当太阳 UV-B 增加时，生产期的缩短可能会降低年生产力。较少的