Advanced

Carbon cycling in subarctic tundra; seasonal variation in ecosystem partitioning based on in situ 14C pulse-labelling

Olsrud, Maria LU and Christensen, Torben LU (2004) In Soil Biology & Biochemistry 36(2). p.245-253
Abstract
Carbon assimilation and allocation were studied in a tundra ecosystem in northern Scandinavia. Seasonal variation in the below-ground carbon allocation to dissolved organic carbon (DOC), coarse-, fine-, and hair roots was investigated using in situ C-14 pulse-labelling, adding 2-3 MBq (CO2)-C-14, dm(-2) to the above-ground vegetation. Combining the allocation data with regression models of the seasonal carbon flux made it possible to estimate a temporally explicit ecosystem carbon allocation budget. The ecosystem was a net source of CO2, losing on average 0.97 gC m(-2) d(-1) to the atmosphere, with little variation through the season. There was, however, significant temporal variation in partitioning of recently assimilated carbon.... (More)
Carbon assimilation and allocation were studied in a tundra ecosystem in northern Scandinavia. Seasonal variation in the below-ground carbon allocation to dissolved organic carbon (DOC), coarse-, fine-, and hair roots was investigated using in situ C-14 pulse-labelling, adding 2-3 MBq (CO2)-C-14, dm(-2) to the above-ground vegetation. Combining the allocation data with regression models of the seasonal carbon flux made it possible to estimate a temporally explicit ecosystem carbon allocation budget. The ecosystem was a net source of CO2, losing on average 0.97 gC m(-2) d(-1) to the atmosphere, with little variation through the season. There was, however, significant temporal variation in partitioning of recently assimilated carbon. Allocation to below-ground compartments over 32 days following labelling increased from 18% in June to 55% in September. Above-ground allocation showed the opposite trend. Hair roots and DOC were strong sinks in the autumn. Transport of newly assimilated carbon occurred rapidly throughout the season, C-14 appearing in all sampled pools within 4 h of labelling. The seasonal variation in carbon partitioning observed in this study has implications for the residence time of assimilated carbon in the ecosystem. A relatively greater allocation to rapidly decomposing pools, such as hair roots and DOC, would tend to reduce incorporation into woody tissue, increasing the overall rate of carbon cycling and decreasing ecosystem storage. The results of this study will be of value for building and validating mechanistic models of ecosystem carbon flow in tundra and subarctic ecosystems. (C) 2003 Elsevier Ltd. All fights reserved. (Less)
Please use this url to cite or link to this publication:
author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
environmental control, seasonal budget, fluxes, carbon, hair root, C-14 pulse-labelling, below-ground allocation, tundra
in
Soil Biology & Biochemistry
volume
36
issue
2
pages
245 - 253
publisher
Elsevier
external identifiers
  • wos:000189081500006
  • scopus:1042290561
ISSN
0038-0717
DOI
10.1016/j.soilbio.2003.08.026
language
English
LU publication?
yes
id
1f7a2785-ef35-4172-a241-582e0f3aef16 (old id 286906)
date added to LUP
2007-10-29 11:03:38
date last changed
2017-07-23 04:38:26
@article{1f7a2785-ef35-4172-a241-582e0f3aef16,
  abstract     = {Carbon assimilation and allocation were studied in a tundra ecosystem in northern Scandinavia. Seasonal variation in the below-ground carbon allocation to dissolved organic carbon (DOC), coarse-, fine-, and hair roots was investigated using in situ C-14 pulse-labelling, adding 2-3 MBq (CO2)-C-14, dm(-2) to the above-ground vegetation. Combining the allocation data with regression models of the seasonal carbon flux made it possible to estimate a temporally explicit ecosystem carbon allocation budget. The ecosystem was a net source of CO2, losing on average 0.97 gC m(-2) d(-1) to the atmosphere, with little variation through the season. There was, however, significant temporal variation in partitioning of recently assimilated carbon. Allocation to below-ground compartments over 32 days following labelling increased from 18% in June to 55% in September. Above-ground allocation showed the opposite trend. Hair roots and DOC were strong sinks in the autumn. Transport of newly assimilated carbon occurred rapidly throughout the season, C-14 appearing in all sampled pools within 4 h of labelling. The seasonal variation in carbon partitioning observed in this study has implications for the residence time of assimilated carbon in the ecosystem. A relatively greater allocation to rapidly decomposing pools, such as hair roots and DOC, would tend to reduce incorporation into woody tissue, increasing the overall rate of carbon cycling and decreasing ecosystem storage. The results of this study will be of value for building and validating mechanistic models of ecosystem carbon flow in tundra and subarctic ecosystems. (C) 2003 Elsevier Ltd. All fights reserved.},
  author       = {Olsrud, Maria and Christensen, Torben},
  issn         = {0038-0717},
  keyword      = {environmental control,seasonal budget,fluxes,carbon,hair root,C-14 pulse-labelling,below-ground allocation,tundra},
  language     = {eng},
  number       = {2},
  pages        = {245--253},
  publisher    = {Elsevier},
  series       = {Soil Biology & Biochemistry},
  title        = {Carbon cycling in subarctic tundra; seasonal variation in ecosystem partitioning based on in situ 14C pulse-labelling},
  url          = {http://dx.doi.org/10.1016/j.soilbio.2003.08.026},
  volume       = {36},
  year         = {2004},
}