Dissertation Research: Black Birch Seedlings as Foragers forNitrogen

论文研究：黑桦幼苗作为氮的采集者

• 批准号: 9016042
• 负责人: Fakhri Bazzaz
• 金额: $ 0.63万
• 依托单位: Harvard University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 1991
• 资助国家: 美国
• 起止时间: 1991-01-15 至 1992-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9016042&HistoricalAwards=false
• 关键词: Dissertation; Research; Black; Birch; Seedlings

Forest regeneration is dependent on the successful growth of individual trees, which are directly affected by soil nitrogen availability. Soil nitrogen is heterogeneously distributed, both in terms of ammonium:nitrate ratio and total quantity. Previous work has shown that black birch seedlings perform differently when fed nitrate in comparison with ammonium, and that this response varies with rate of nitrogen supplied and light level. Using a split pot design to create patches of different ammonium to nitrate ration, the investigators will examine whether black birch seedlings forage selectively for nitrate or ammonium in soil. By using labelled 15NO3, they will test whether roots actually prefer to acquire ammonium, and whether preference for a given form of nitrogen is dependent upon the ratio of ammonium to nitrate in a patch, the rate of nitrogen supply and light availability. Lastly, the investigators will examine whether the ratio of total non-structural carbohydrates: free amino acids in the leaves is a good predictor of whole plant partitioning of biomass.

森林更新依赖于个体树木的成功生长，而个体树木的生长直接受到土壤氮素有效性的影响。土壤氮素在氨氮与硝态氮的比例和总量上均呈不均匀分布。以前的工作表明，与氨氮相比，黑桦幼苗在供应硝酸盐时表现不同，这种反应随着氮素供应速度和光照水平的不同而不同。使用分体式盆栽设计来创造不同的铵与硝酸盐比例，调查人员将检查黑桦树幼苗是否有选择地在土壤中寻找硝酸盐或铵。通过使用标记的15NO3，他们将测试根系是否真的更喜欢获取铵，以及对给定形式的氮的偏好是否取决于斑块中铵与硝酸盐的比例、氮素供应速度和光可获得性。最后，研究人员将检验叶片中总非结构性碳水化合物与游离氨基酸的比率是否能很好地预测整个植物对生物量的分配。