气候变化领域集成服务门户(CCPortal): Discrimination in Tree Stems O2 Uptake and the Dole Effect

CCPortal

DOI	10.1029/2018GB005918
	Discrimination in Tree Stems O2 Uptake and the Dole Effect
	Hilman B.; Angert A.
发表日期	2018
ISSN	0886-6236
EISSN	1944-9224
起始页码	1208
结束页码	1225
卷号	32 期号:8
英文摘要	The difference in δ18O between the atmospheric O2 and seawater is named the Dole effect (DE). Interpretation of past DE variations, a proxy for monsoonal intensity, is based on current understanding of global O2 fluxes. One such O2 flux that was poorly studied is the discrimination in O2 uptake by tree stems (Dstem). Stems differ from leaves in their lower gas permeability, which reduces the internal [O2] and poses diffusion limitations to local respiration. Diffusion limitations are expected to lower the effective discrimination below enzymatic values (17–30‰). Given fixed permeability, the lowest internal [O2] and thus the greatest diffusional effect are expected in high O2 influx. Dstem and O2 influx values were obtained by measurements of stem-chamber air and a numerical model that resolves the gas exchange in the chamber. According to 101 results of temperate, Mediterranean, and tropical trees, the global Dstem is 19.2‰. Assuming basal O2 diffusion limitation in the stems, the results indicate involvement of the alternative oxidase respiration, with enzymatic discrimination factor of above 20‰. Small seasonal variations in Dstem were uncoupled from the O2 influx rates that tracked the temperature changes. This indicates a possible adjustment between the aeration capability of the stems and O2 uptake rate, which helps to maintain sufficient O2 supply. The mean Dstem value agrees with the assumed discrimination for leaf respiration, thus supporting current DE understanding. The small Dstem seasonal variations give an indication that climate variations on millennial and interglacial scales did not have a strong effect on Dstem values. ©2018. American Geophysical Union. All Rights Reserved.
英文关键词	alternative respiration; diffusion; Dole effect; oxygen isotopes; oxygen uptake; stem respiration
语种	英语
scopus关键词	aeration; climate change; enzyme activity; gas exchange; interglacial; numerical model; oxygen isotope; respiration; seasonal variation; seawater; temperature effect
来源期刊	Global Biogeochemical Cycles
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/129805
作者单位	The Fredy and Nadine Herrmann Institute of Earth Sciences, The Hebrew University of Jerusalem, Jerusalem, Israel
推荐引用方式 GB/T 7714	Hilman B.,Angert A.. Discrimination in Tree Stems O2 Uptake and the Dole Effect[J],2018,32(8).
APA	Hilman B.,&Angert A..(2018).Discrimination in Tree Stems O2 Uptake and the Dole Effect.Global Biogeochemical Cycles,32(8).
MLA	Hilman B.,et al."Discrimination in Tree Stems O2 Uptake and the Dole Effect".Global Biogeochemical Cycles 32.8(2018).