• 主题
高级搜索  >
历史搜索 清空历史
首页> 外文学位 >Physiological and growth responses of grassland species to elevated carbon dioxide and increased nitrogen supply with emphasis on symbiotic nitrogen fixers vs. non-fixers.
【24h】

Physiological and growth responses of grassland species to elevated carbon dioxide and increased nitrogen supply with emphasis on symbiotic nitrogen fixers vs. non-fixers.

机译：草地物种对二氧化碳升高和氮供应增加的生理和生长响应，重点是共生固氮剂与非固氮剂。

获取原文
获取原文并翻译 | 示例
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

Although rising atmospheric concentrations of carbon dioxide (CO 2) and increasing nitrogen (N) deposition are well-documented global changes, their interactive effects on vegetation are not well understood. This thesis characterizes the physiological and growth responses of perennial grassland species to combinations of atmospheric CO2 and N treatments. Mechanisms operating at leaf, whole-plant, and community levels were studied using species adapted to N-limited habitats with emphasis on species capable of accessing atmospheric N through symbiotic N2 fixation.; The response of leaf-level gas exchange was measured for 13 species in field plots exposed to ambient (368 μmol mol−1) and elevated (560 μmol mol−1) CO2 concentrations combined with unamended and enriched (+4 gN m−2 yr −1) N treatments. All species showed pronounced photosynthetic acclimation resulting in minimal stimulation (7%) of photosynthesis with CO 2 enrichment. Elevated CO2 decreased stomatal conductance (24%), leading to increases in intrinsic water-use efficiency. Increased N supply did not affect leaf-level responses to elevated CO2. The substantial acclimation of photosynthesis was associated with decreases in stomatal conductance and leaf N in response to CO2 enrichment.; To further investigate the effect of N availability on the CO2 response, growth and physiological responses to elevated CO2 were compared between an N2-fixer and a non-N2-fixer across a range of N additions in a growth chamber study. The N2-fixer derived 32% more N from symbiotic N2 fixation and accumulated 80% more biomass, regardless of N addition, under elevated compared to ambient CO2. In contrast, the growth response to CO2 enrichment of the non-N2-fixer was limited at low N.; The hypothesis that N2-fixers will alleviate N-limitations on the CO2 responses of plants and communities was evaluated in multi-species field assemblages. Photosynthesis and plant and soil N status were enhanced by the presence of an N2-fixer, however this did not facilitate greater responses of non-N2-fixers to elevated compared to ambient CO2.; Interspecific variation in acclimation of photosynthesis to CO2 enrichment and N availability, and the contrasting growth responses of N2-fixers and non-N2-fixers, will be important determinants of the response of vegetation to future environments. Furthermore, species interactions may critically modify plant and community responses to these global changes.
机译：尽管大气中二氧化碳（CO 2 ）的浓度升高和氮（N）沉积物的增加是有据可查的全球变化，但人们对它们对植被的相互作用的影响尚不清楚。本文描述了多年生草地物种对大气CO 2 和N处理组合的生理和生长响应。研究了在适应氮有限的生境的物种在叶片，整株和群落水平上的运转机制，重点是能够通过共生N 2 固定获取大气氮的物种。在暴露于环境（368μmolmol -1 ）和升高的（560μmolmol -1 ）CO的田地中，测量了13种植物叶片水平气体交换的响应。 2 浓度与未经修正和富集（+4 gN m −2 yr -1 ）N处理组合。所有物种均表现出明显的光合作用适应性，导致CO 2 富集对光合作用的刺激最小（7％）。 CO 2 升高会降低气孔导度（24％），从而导致内在水分利用效率的提高。氮素供应的增加并没有影响叶片水平对CO 2 升高的响应。光合作用的大量适应与气孔导度和叶片N对CO 2 富集的响应降低有关。为了进一步研究氮素有效性对CO 2 反应的影响，在N 2 -之间比较了对升高的CO 2 的生长和生理反应。生长室研究中，在一定范围内添加N的固定剂和非N 2 固定剂。与环境CO 相比，N 2 固色剂从共生N 2 固色剂中获取的N增加了32％，并且在不考虑氮添加的情况下累积了80％的生物量2 。相反，在低氮下，对非N 2 固定剂对CO 2 富集的生长响应受到限制。在多物种田间组合中评估了N 2 固定剂将减轻植物和群落对CO 2 响应的N限制的假说。 N 2 -固色剂的存在增强了光合作用以及植物和土壤的氮素状态，但这与非N 2 -固色剂相比对更高的响应没有促进作用。到环境CO 2 。光合作用对CO 2 富集和氮素利用的种间差异以及N 2 固定剂和非N 2 的对比生长响应-固定剂，将是决定植被对未来环境的重要决定因素。此外，物种之间的相互作用可能会严重改变植物和群落对这些全球变化的反应。

著录项

  • 作者

    Lee, Tali Delius.;

  • 作者单位

    University of Minnesota.;

  • 授予单位 University of Minnesota.;
  • 学科 Biology Plant Physiology.; Biology Ecology.
  • 学位 Ph.D.
  • 年度 2001
  • 页码 121 p.
  • 总页数 121
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 植物学;生态学（生物生态学）;
  • 关键词

相似文献

  • 外文文献
  • 中文文献
  • 专利
获取原文

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号