DOI: 10.1111/gcb.14555
Scopus记录号: 2-s2.0-85061933062
论文题名: Lower photorespiration in elevated CO 2 reduces leaf N concentrations in mature Eucalyptus trees in the field
作者: Wujeska-Klause A. ; Crous K.Y. ; Ghannoum O. ; Ellsworth D.S.
刊名: Global Change Biology
ISSN: 13541013
出版年: 2019
卷: 25, 期: 4 起始页码: 1282
结束页码: 1295
语种: 英语
英文关键词: carbohydrates
; EucFACE
; leaf age
; nitrate
; nitrate reductase
; nitrogen assimilation
; photorespiration
; photosynthesis
Scopus关键词: Eucalyptus
英文摘要: Rising atmospheric CO 2 concentrations is expected to stimulate photosynthesis and carbohydrate production, while inhibiting photorespiration. By contrast, nitrogen (N) concentrations in leaves generally tend to decline under elevated CO 2 (eCO 2 ), which may reduce the magnitude of photosynthetic enhancement. We tested two hypotheses as to why leaf N is reduced under eCO 2 : (a) A “dilution effect” caused by increased concentration of leaf carbohydrates; and (b) inhibited nitrate assimilation caused by reduced supply of reductant from photorespiration under eCO 2 . This second hypothesis is fully tested in the field for the first time here, using tall trees of a mature Eucalyptus forest exposed to Free-Air CO 2 Enrichment (EucFACE) for five years. Fully expanded young and mature leaves were both measured for net photosynthesis, photorespiration, total leaf N, nitrate (NO − 3 ) concentrations, carbohydrates and NO − 3 reductase activity to test these hypotheses. Foliar N concentrations declined by 8% under eCO 2 in new leaves, while the NO − 3 fraction and total carbohydrate concentrations remained unchanged by CO 2 treatment for either new or mature leaves. Photorespiration decreased 31% under eCO 2 supplying less reductant, and in situ NO − 3 reductase activity was concurrently reduced (−34%) in eCO 2 , especially in new leaves during summer periods. Hence, NO − 3 assimilation was inhibited in leaves of E. tereticornis and the evidence did not support a significant dilution effect as a contributor to the observed reductions in leaf N concentration. This finding suggests that the reduction of NO − 3 reductase activity due to lower photorespiration in eCO 2 can contribute to understanding how eCO 2 -induced photosynthetic enhancement may be lower than previously expected. We suggest that large-scale vegetation models simulating effects of eCO 2 on N biogeochemistry include both mechanisms, especially where NO − 3 is major N source to the dominant vegetation and where leaf flushing and emergence occur in temperatures that promote high photorespiration rates. © 2019 John Wiley & Sons Ltd Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/117455
Appears in Collections: 气候变化与战略
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Recommended Citation:
Wujeska-Klause A.,Crous K.Y.,Ghannoum O.,et al. Lower photorespiration in elevated CO 2 reduces leaf N concentrations in mature Eucalyptus trees in the field[J]. Global Change Biology,2019-01-01,25(4)