Collaborative Research: Distribution of Photosynthetic Capacity in Conifer Canopies: The Role of Shoot Geometry, Leaf Morphology and Nitrogen Concentration

合作研究：针叶树冠层光合能力的分布：芽几何形状、叶子形态和氮浓度的作用

• 批准号: 9613350
• 负责人: Barbara Bond
• 金额: $ 7.98万
• 依托单位: Oregon State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 1996
• 资助国家: 美国
• 起止时间: 1996-07-15 至 1999-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9613350&HistoricalAwards=false
• 关键词: Collaborative; Research; Distribution; Photosynthetic; Capacity

9613350 Yoder Nitrogen is one of the most important elements controlling plant growth in both natural and agricultural ecosystems. Ecophysiology theory suggests that the distribution of nitrogen within a plant canopy should match the distribution of intercepted light; that is, there should be much more nitrogen near the top of the canopy (where light levels are highest) than in the more shaded areas near the bottom of the canopy. However, when theoretical predictions have been compared with actual plant canopies, the results have been mixed at best. Nitrogen distribution in most canopies does show the same general pattern as that predicted by theory. However, the mechanism by which nitrogen content changes differs between species, and the difference in nitrogen levels from the top to the bottom of the canopy is rarely as large as the theory predicts that it should be. The investigators have developed a hypothesis that explains this variation in mechanismsand also suggests some reasons why the variation in nitrogen does notalways match the pattern of light distribution, especially in older leaves. They propose to test this hypothesis in three different western conifer species: Douglas-fir (Pseudotsuga menziesii), the most important timber species in the Pacific Northwest; Pacific silver fir (Abies amabilis) an important tree of high altitude forests; and ponderosa pine (Pinus ponderosa), the dominant tree in dry forests throughout the western United States. If the hypothesis proves correct, it will provide a better understanding of the organizing principles for shoot structure and function within complex canopies, and will assist in efforts to "scale up" gas fluxes from leaves to canopies--a critical component of attempts to model and predict the consequences of climate change in western conifer forests.

小行星9613350 氮是自然生态系统和农业生态系统中控制植物生长的重要元素之一。 生态生理学理论认为，氮在植物冠层内的分布应该与被截获的光的分布相匹配;也就是说，在冠层顶部附近（光照水平最高的地方）应该有更多的氮 而不是树冠底部阴影区域。 然而，当理论预测与实际的植物冠层进行比较时，结果充其量是混合的。大多数树冠中的氮分布确实表明 与理论预测的一般模式相同。 然而，氮含量变化的机制因物种而异，从树冠顶部到底部的氮水平差异很少像理论预测的那样大。 研究人员提出了一个假说，解释了这种变化的机制，也提出了一些原因，为什么氮的变化并不总是与光分布的模式相匹配，特别是在老叶中。 他们建议在三个不同的西方国家测试这一假设。 针叶 物种： 花旗松 （Pseudotsuga menziesii），太平洋西北地区最重要的木材树种;太平洋银冷杉（Abies amabilis），高海拔森林的重要树种;和黄松（Pinus ponderosa），美国西部干旱森林的主要树种。 如果这一假设被证明是正确的，它将提供一个更好的理解的组织原则，复杂的冠层内的拍摄结构和功能，并将有助于努力“按比例增加”气体通量从树叶到冠层-一个关键组成部分，试图模拟和预测气候变化的后果在西部针叶林。