Ecosystem Responses to Stratospheric Ozone Reduction

生态系统对平流层臭氧减少的反应

• 批准号: 9524144
• 负责人: Martyn Caldwell
• 金额: $ 44.4万
• 依托单位: Utah State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 1995
• 资助国家: 美国
• 起止时间: 1995-09-15 至 1999-02-28
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9524144&HistoricalAwards=false
• 关键词: Ecosystem; Responses; Stratospheric; Ozone; Reduction

9524144 Stratospheric ozone loss, resulting primarily from chemicals generated by human activities, results in an increased amount of solar ultraviolet-B radiation reaching the earth. Ultraviolet-B radiation is capable of damaging biological systems, including DNA. Only a modest amount of research, however, has been directed toward the potential biological consequences of stratospheric ozone depletion, and virtually nothing has been done at the level of terrestrial ecosystems. This research is an ecosystem-level study of the responses to elevated solar ultraviolet-B resulting near Ushuaia, Argentina. The site is on the southern tip of South America across the Drake Passage from the Antarctic Peninsula. This location experiences more pronounced ozone reduction than at anywhere else in the world where terrestrial ecosystems with appreciable plant cover occur. Three phenomena contribute to this: The so-called "ozone hole" can pass directly overhead, parcels of ozone-depleted air can float northward from the ozone hole, and a general erosion of the ozone layer is most prominent at high latitudes and in the Southern Hemisphere. At the study site, extremely high fluxes of ultraviolet-B can occur when skies are clear and, when cloudy, there can be very high ultraviolet-B relative to total solar radiation. Thus, this will be an extreme case study to determine ecosystem-level effects of ozone reduction. A three-year, on-site field study of a shrub-grass community will be conducted. Effects of elevated ultraviolet-B will assessed for both acute exposures, such as when the ozone hole passes overhead and as chronic, growing-season and multi-season exposures to elevated ultraviolet-B. For responses to acute exposures to high ultraviolet-B and high ultraviolet-B/(total solar radiation) ratios, damage to DNA and photosynthesis will be determined. Acute exposures will be studied both as natural events (tracking the precession of the ozone hole by downloading satellite-based images and anticipating overhead passage) and by simulating such occurrences with special UV lamp systems. Most of the effort will be directed to effects of chronic exposures at the population level (e.g., reproduction and expansion or contraction of plant populations) and at the ecosystem level. Researchers will determine changes in competitive balance among species, timing of annual biological events, plant consumption by insects, and decomposition of plant litter. If solar ultraviolet-B affects such ecosystem-level processes, there are many implications for the function and integrity of these systems. Preliminary evidence collected recently in Argentina shows large effects of sunlight ultraviolet-B on DNA damage, plant growth and insect herbivory. Changes in litter decomposition may affect ecosystem carbon balance and atmospheric carbon dioxide concentrations. Knowledge of the direction and magnitude of such changes is essential if we are to predict the biological consequences of changing atmospheric chemistry and develop rational management strategies.

9524144平流层臭氧损失主要是由人类活动产生的化学物质造成的，导致到达地球的太阳紫外线B辐射量增加。紫外线-B辐射能够破坏包括DNA在内的生物系统。然而，只有少量的研究针对平流层臭氧消耗的潜在生物学后果，而在陆地生态系统层面上几乎没有任何研究。这项研究是一项生态系统层面的研究，研究阿根廷乌斯怀亚附近对太阳紫外线B升高的反应。该遗址位于南美洲南端，与南极半岛隔着德雷克海峡。这个地区的臭氧减少比世界上任何其他地方都要明显，在那里，陆地生态系统出现了明显的植物覆盖。造成这一现象的原因有三个：所谓的“臭氧层空洞”可以直接从头顶通过，大量消耗臭氧的空气可以从臭氧层空洞向北漂移，臭氧层的普遍侵蚀在高纬度和南半球最为突出。在研究地点，当天空晴朗时，可能会出现极高的紫外线-B通量，而当多云时，相对于太阳总辐射，可能会有非常高的紫外线-B。因此，这将是一个极端的案例研究，以确定臭氧减少对生态系统的影响。将对一个灌木-草群落进行为期三年的实地研究。将评估紫外线B浓度升高对急性暴露的影响，例如当臭氧空洞从头顶经过时，以及长期、生长季节和多季节暴露在紫外线B浓度升高的情况下。对于对高紫外线-B和高紫外线-B/(总太阳辐射)比率的急性暴露的反应，将确定对DNA和光合作用的损害。急性暴露将作为自然事件(通过下载卫星图像和预测空中通道来跟踪臭氧层空洞的进动)和通过特殊的紫外线灯系统模拟此类事件来研究。大部分工作将针对长期暴露在种群一级(例如，植物种群的繁殖和扩张或收缩)和生态系统一级的影响。研究人员将确定物种间竞争平衡的变化、年度生物事件的时间安排、昆虫对植物的消耗以及植物凋落物的分解。如果太阳紫外线B影响这种生态系统水平的过程，对这些系统的功能和完整性有许多影响。最近在阿根廷收集的初步证据表明，阳光紫外线B对DNA损伤、植物生长和昆虫食草性有很大影响。凋落物分解的变化可能会影响生态系统碳平衡和大气二氧化碳浓度。如果我们要预测大气化学变化的生物后果并制定合理的管理战略，了解这种变化的方向和程度是至关重要的。