树环 δ15N作为一个动态的指标,与N2固定Alnus rubra树立与N2固定
L Nehring1, J M Kranabetter2, G J Harper3
1Centre for Forest Biology, University of Victoria, PO Box 3020, STN CSC, 3800 Finnerty Road,Victoria, British Columbia V8P 5C2, Canada.
Tree physiology
|September 6, 2023
概括
红中的树环同位素 (δ15N) 反映了土壤的动态,显示了最初的增加,然后是平原. 在混合种群中,道格拉斯 δ15N 的含量更高,这表明的气影响.
科学领域:
- 生态生态学 生态生态学
- 森林科学 森林科学 森林科学
- 生物地质化学生物地质化学
背景情况:
- 树环稳定同位素,特别是 (δ15N),有可能重建长期 (N) 动态在固物种的森林.
- 然而,将树环 δ15N 模式与土壤 N 动态和 N 固定树中的 N 积累率联系起来的实证现场数据很少,解释仍在争论中.
- 了解这些关系对于评估N2固定树在森林生态系统中的生态作用至关重要.
研究的目的:
- 为了调查红 (Alnus rubra) 的树环 δ15N 是否准确地反映了土壤 N 积累和 δ15N.
- 为了确定红所固定的是否会影响邻近的沿海道格拉斯 (Pseudotsuga menziesii) 的δ15N特征.
- 为了评估 δ15N 在树环中的时间模式,与土壤 N 动态相对应,在不同比例的红和道格拉斯火焰下.
主要方法:
- 建立了一个27年的替代系列实验,使用五种种植比例 (0100%) 的红和道格拉斯.
- 分析了森林地面土壤的N含量和δ15N,以及两种物种的树环δ15N.
- 树环 δ15N 的时间趋势是使用二次匹配来建模的,以评估27年期间的变化.
主要成果:
- 增加红的比例显著增加了森林地表的N含量和δ15N值.
- 红树环 δ15N 呈现出二次趋势,最初增加,然后平稳或略有下降.
- 道格拉斯树树环 δ15N 随着时间的推移保持稳定,但在 50/50 混合群中显著上升,这表明N 从树转移.
结论:
- 红中的树环 δ15N 提供了特定地点气动态的记录,反映了 N 积累和土壤同位素特征.
- 观测到的树环 δ15N 的平原或下降可能表明,由于诸如树活力下降或酸盐可用性增加等因素,N2 固定率降低.
- 来自混合种群的道格拉斯的高达15N证实了固定对邻近的非固定树的影响.
更多相关视频
08:05Measurement of the Potential Rates of Dissimilatory Nitrate Reduction to Ammonium Based on 14NH4+/15NH4+ Analyses via Sequential Conversion to N2O
Published on: October 7, 2020
6.2K
07:40Advanced Workflow for Taking High-Quality Increment Cores - New Techniques and Devices
Published on: March 10, 2023
2.2K
相关概念视频
01:16Other Nuclides: 31P, 19F, 15N NMR
410
Many organic, inorganic, and biological molecules contain spin-half nuclei such as nitrogen-15, fluorine-19, and phosphorus-31. As a result, NMR studies of these nuclei have found extensive applications in chemical and biological research.
While fluorine-19 and phosphorous-31 have high natural abundances (100%) and positive gyromagnetic ratios, nitrogen-15 has a low natural abundance and a negative gyromagnetic ratio. However, nitrogen-15 is still preferred over nitrogen-14 (which has a...
While fluorine-19 and phosphorous-31 have high natural abundances (100%) and positive gyromagnetic ratios, nitrogen-15 has a low natural abundance and a negative gyromagnetic ratio. However, nitrogen-15 is still preferred over nitrogen-14 (which has a...
410
01:19NMR Spectroscopy Of Amines
8.9K
In proton NMR spectroscopy, primary amines and secondary amines showcase their N–H protons as a broad signal in the chemical shift range between δ 0.5 and 5 ppm. The exact position in this range depends on several factors, including sample concentration, hydrogen bonding, and the type of solvent used. Since amine protons undergo fast proton exchange in solution, the protons are labile and therefore do not participate in any splitting with adjacent protons. Thus, the observed peak is...
8.9K
01:22Inorganic Nitrogen Assimilation
44
Nitrogen is an essential element in biological systems, forming a crucial component of proteins, nucleic acids, and other cellular constituents. Many bacteria and archaea acquire nitrogen in the form of nitrate (NO₃⁻) or ammonia (NH₃), which are then assimilated into biomolecules through specific enzymatic pathways.Assimilatory Nitrate ReductionWhen nitrate enters the cell, it undergoes a two-step reduction process known as assimilatory nitrate reduction. Initially, the enzyme...
44
01:10Carbon-13 (¹³C) NMR: Overview
5.8K
Carbon-13 is a naturally occurring NMR-active isotope of carbon with a low natural abundance of 1.1%. In contrast, carbon-12 is the most abundant isotope of carbon with zero nuclear spin. Therefore, it is NMR inactive. The gyromagnetic ratio of carbon-13 is smaller than that of protons. As a result, carbon-13 resonance is about 6000 times weaker than proton resonance. For a given magnetic field strength, the resonance frequency of carbon-13 is about one-fourth of the resonance frequency for...
5.8K