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Leaf metabolic and morphological responses of dwarf willow (Salix herbacea) in the sub-arctic to the past 9000 years of global environmental change

Beerling, D. J. and Rundgren, M. LU (2000) In New Phytologist 145(2). p.257-269
Abstract

Ice-core records of the concentration of atmospheric CO2 and its stable isotope ratio (δ13C(a)) have shown that the global C cycle has not remained in steady-state over the past 11000 yr, implying a possible change in vegetation activity over this period. Here we evaluated the ecophysiological responses of the dwarf willow (Salix herbacea) over the past 9000 yr by measuring the stable carbon isotope composition and stomatal characters of a unique, well dated, high-latitude (68°N) sub-fossil leaf sequence. After correction for corresponding changes in δ13C(a), 9000-yr record of variations in the ratio of intercellular (c(j)) to atmospheric (c(a)) CO2 concentration was established.... (More)

Ice-core records of the concentration of atmospheric CO2 and its stable isotope ratio (δ13C(a)) have shown that the global C cycle has not remained in steady-state over the past 11000 yr, implying a possible change in vegetation activity over this period. Here we evaluated the ecophysiological responses of the dwarf willow (Salix herbacea) over the past 9000 yr by measuring the stable carbon isotope composition and stomatal characters of a unique, well dated, high-latitude (68°N) sub-fossil leaf sequence. After correction for corresponding changes in δ13C(a), 9000-yr record of variations in the ratio of intercellular (c(j)) to atmospheric (c(a)) CO2 concentration was established. Intercellular: atmospheric CO2 concentration ratios provide a time-integrated indicator of the set-point of leaf gas exchange, and the historical variations revealed in this record have been interpreted as an impact of environmental changes on leaf gas exchange. The sequence shows a progressive fall in c(i)/c(a) 9000-3000 yr BP as well as the climatic effects of the Medieval Warm Period, the Little Ice Age and the post-industrial CO2 rise. Leaf stomatal index (proportion of epidermal cells as stomata), but not stomatal density, was significantly (P <0.01) correlated with Holocene atmospheric CO2 variations. A process-based interpretation of the changes in c(i)/c(a) was made using two different coupled photosynthesis-stomatal conductance models. Calculated in this way, S. herbacea photosynthetic rates were relatively stable throughout the Holocene whilst stomatal conductance progressively declined. Both, however, showed the marked effects of the Medieval Warm Period and the Little Ice Age. Overall, the results demonstrate that S. herbacea leaf metabolism, like the global C cycle, has not remained in steady state during the Holocene but has responded to changes in atmospheric CO2 concentration and short-term climatic oscillations.

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author
and
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Atmospheric CO, Leaf gas exchange, Modelling, Stable carbon isotopes, Stomata, Sub-fossil leaves
in
New Phytologist
volume
145
issue
2
pages
13 pages
publisher
Wiley-Blackwell
external identifiers
  • scopus:0034097312
ISSN
0028-646X
DOI
10.1046/j.1469-8137.2000.00582.x
language
English
LU publication?
yes
id
02e5d17f-c781-4030-bf1a-102e5fdae457
date added to LUP
2019-05-20 11:21:45
date last changed
2020-07-01 05:09:11
@article{02e5d17f-c781-4030-bf1a-102e5fdae457,
  abstract     = {<p>Ice-core records of the concentration of atmospheric CO<sub>2</sub> and its stable isotope ratio (δ<sup>13</sup>C(a)) have shown that the global C cycle has not remained in steady-state over the past 11000 yr, implying a possible change in vegetation activity over this period. Here we evaluated the ecophysiological responses of the dwarf willow (Salix herbacea) over the past 9000 yr by measuring the stable carbon isotope composition and stomatal characters of a unique, well dated, high-latitude (68°N) sub-fossil leaf sequence. After correction for corresponding changes in δ<sup>13</sup>C(a), 9000-yr record of variations in the ratio of intercellular (c(j)) to atmospheric (c(a)) CO<sub>2</sub> concentration was established. Intercellular: atmospheric CO<sub>2</sub> concentration ratios provide a time-integrated indicator of the set-point of leaf gas exchange, and the historical variations revealed in this record have been interpreted as an impact of environmental changes on leaf gas exchange. The sequence shows a progressive fall in c(i)/c(a) 9000-3000 yr BP as well as the climatic effects of the Medieval Warm Period, the Little Ice Age and the post-industrial CO<sub>2</sub> rise. Leaf stomatal index (proportion of epidermal cells as stomata), but not stomatal density, was significantly (P &lt;0.01) correlated with Holocene atmospheric CO<sub>2</sub> variations. A process-based interpretation of the changes in c(i)/c(a) was made using two different coupled photosynthesis-stomatal conductance models. Calculated in this way, S. herbacea photosynthetic rates were relatively stable throughout the Holocene whilst stomatal conductance progressively declined. Both, however, showed the marked effects of the Medieval Warm Period and the Little Ice Age. Overall, the results demonstrate that S. herbacea leaf metabolism, like the global C cycle, has not remained in steady state during the Holocene but has responded to changes in atmospheric CO<sub>2</sub> concentration and short-term climatic oscillations.</p>},
  author       = {Beerling, D. J. and Rundgren, M.},
  issn         = {0028-646X},
  language     = {eng},
  month        = {02},
  number       = {2},
  pages        = {257--269},
  publisher    = {Wiley-Blackwell},
  series       = {New Phytologist},
  title        = {Leaf metabolic and morphological responses of dwarf willow (Salix herbacea) in the sub-arctic to the past 9000 years of global environmental change},
  url          = {http://dx.doi.org/10.1046/j.1469-8137.2000.00582.x},
  doi          = {10.1046/j.1469-8137.2000.00582.x},
  volume       = {145},
  year         = {2000},
}