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首页> 外文学位 >Direct and indirect effects of elevated carbon dioxide and ozone on the canopy of a soybean agroecosystem.
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Direct and indirect effects of elevated carbon dioxide and ozone on the canopy of a soybean agroecosystem.

机译：二氧化碳和臭氧浓度升高对大豆农业生态系统冠层的直接和间接影响。

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摘要

It is unknown how rising atmospheric CO2 and O3 will directly and indirectly alter canopy structure and scale to affect ecosystems. I determined how leaf area index (LAI) was directly affected by elevated [CO 2] and [O3]. By increasing photosynthetic efficiency, elevated [CO2] may increase maximum LAI. However, [O3] accelerates senescence and may reduce LAI. My second objective was to determine how changes in canopy size altered the radiation use efficiency of the canopy in elevated [CO2] and [O3]. Radiation use efficiency (&egr;) is a measure of the conversion efficiency of absorbed radiation (APAR) into biomass. I expected elevated [CO2] to increase &egr; however, elevated [O3] may have the opposite effect. Folivorous insects indirectly reduce canopy size through the removal of leaf area, and the changes in leaf chemistry in elevated [CO2] and [O3] may lead to increased herbivory. These predictions were tested using Soy bean F&barbelow;ree-A&barbelow;ir C&barbelow;oncentration E&barbelow;nrichment technology (SoyFACE) with plots exposed to ambient air (∼370ppm), elevated CO2 (∼550ppm) and elevated O3 (1.2*ambient). Elevated [CO2] increased maximum LAI and delayed LAI loss to senescence, although the effects varied among years. Elevated [O3] consistently reduced LAI by accelerating senescence. These effects combined with corresponding changes in biomass, to increase &egr; in elevated [CO2] and reduce &egr; in elevated [O3]. Increased &egr; in elevated [CO2] was driven primarily by increased biomass however, in elevated [O3] increased LAI loss to senescence droves decrease in biomass. Growth in elevated [CO2] increased the susceptibility of soybeans to herbivory, particularly by non-native insects. Chronic exposure to elevated [O3] produced few significant effects on herbivory. The impacts of altered tropospheric chemistry on soybeans will be complicated by the complex behavior of insect pests and their indirect effects on plant canopies and productivity.
机译：未知的是，大气中二氧化碳和氧气的上升将如何直接和间接改变冠层结构和规模以影响生态系统。我确定了叶面积指数（LAI）如何直接受到[CO 2]和[O3]升高的影响。通过提高光合作用效率，提高的[CO2]可能会增加最大LAI。但是，[O3]加速衰老并可能降低LAI。我的第二个目标是确定在[CO2]和[O3]升高时，冠层尺寸的变化如何改变冠层的辐射利用效率。辐射利用效率（＆egr;）是吸收辐射（APAR）转化为生物质的转化效率的度量。我预计升高的[CO2]会增加＆egr;但是，升高的[O3]可能具有相反的效果。食叶昆虫通过去除叶面积间接减少冠层大小，升高的[CO2]和[O3]的叶片化学变化可能导致草食性增加。这些预测是使用大豆F＆barbelow; ree-A＆barir; ir C＆barbelow;浓缩E＆barbelow;富集技术（SoyFACE）在地块暴露于环境空气（〜370ppm），CO2升高（〜550ppm）和O3升高（1.2 *环境）的情况下进行的。升高的[CO2]增加了最大LAI并延迟了LAI衰老至衰老，尽管其影响因年份而异。升高的[O3]可通过加速衰老来持续降低LAI。这些影响与生物量的相应变化相结合，从而增加＆egr;增加[CO2]并降低＆egr;在升高的[O3]中。 ＆egr;增加升高的[CO2]中的生物量主要由增加的生物量驱动，但是，升高的[O3]中的LAI损失增加到衰老，生物量减少。升高的[CO2]的生长增加了大豆对草食动物的敏感性，特别是对非本地昆虫而言。长期暴露于升高的[O3]对草食动物几乎没有产生显着影响。对流层化学变化对大豆的影响将因虫害的复杂行为及其对植物冠层和生产力的间接影响而变得复杂。

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  • 作者

    Dermody, Orla C.;

  • 作者单位

    University of Illinois at Urbana-Champaign.;

  • 授予单位 University of Illinois at Urbana-Champaign.;
  • 学科 Agriculture Agronomy.; Biology Ecology.; Biology Plant Physiology.
  • 学位 Ph.D.
  • 年度 2006
  • 页码 126 p.
  • 总页数 126
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 农学（农艺学）;生态学（生物生态学）;植物学;
  • 关键词

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