Moisture effects on temperature sensitivity of CO2 exchange in a subarctic heath ecosystem

Research output: Contribution to journalArticle

Standard

Moisture effects on temperature sensitivity of CO2 exchange in a subarctic heath ecosystem. / Illeris, L; Christensen, Torben; Mastepanov, Mikhail.

In: Biogeochemistry, Vol. 70, No. 3, 2004, p. 315-330.

Research output: Contribution to journalArticle

Harvard

APA

CBE

MLA

Vancouver

Author

RIS

TY - JOUR

T1 - Moisture effects on temperature sensitivity of CO2 exchange in a subarctic heath ecosystem

AU - Illeris, L

AU - Christensen, Torben

AU - Mastepanov, Mikhail

PY - 2004

Y1 - 2004

N2 - Carbon fluxes between natural ecosystems and the atmosphere have received increased attention in recent years due to the impact they have on climate. In order to investigate independently how soil moisture and temperature control carbon fluxes into and out of a dry subarctic dwarf shrub dominated heath, monoliths containing soil and plants were incubated at three different moisture levels and subjected to four different temperature levels between 7 and 20degreesC. Ecosystem CO2 exchange was monitored continuously day and night during the 16 to 18 days that each of three experiments lasted. Additionally, the carbon allocation pattern of the plants was investigated by labelling monoliths with (CO2)-C-14 followed by harvest of above and below ground plant parts. The results revealed that the three different soil moisture levels caused distinctly differing levels Of CO2 fluxes. Also, both carbon fixation calculated as gross ecosystem production (GEP) and carbon release measured as ecosystem respiration (ER) increased with increasing temperatures, with ER increasing faster than GER Hence, short term carbon loss from the ecosystem accelerated with raised temperatures. Temperature sensitivity of the ecosystem was dependent on the soil moisture level, shown by differing Q(10) values of both GEP and ER at different soil moisture levels. It is therefore highly important to take soil moisture levels into consideration when evaluating responses of ecosystem carbon balance to changes in temperature. The greatest C fixation took place via the two most dominant species of the ecosystem, Vaccinium uliginosum and Empetrum hermaphroditum, with the former being responsible for the different size of C fixation at the three moisture levels.

AB - Carbon fluxes between natural ecosystems and the atmosphere have received increased attention in recent years due to the impact they have on climate. In order to investigate independently how soil moisture and temperature control carbon fluxes into and out of a dry subarctic dwarf shrub dominated heath, monoliths containing soil and plants were incubated at three different moisture levels and subjected to four different temperature levels between 7 and 20degreesC. Ecosystem CO2 exchange was monitored continuously day and night during the 16 to 18 days that each of three experiments lasted. Additionally, the carbon allocation pattern of the plants was investigated by labelling monoliths with (CO2)-C-14 followed by harvest of above and below ground plant parts. The results revealed that the three different soil moisture levels caused distinctly differing levels Of CO2 fluxes. Also, both carbon fixation calculated as gross ecosystem production (GEP) and carbon release measured as ecosystem respiration (ER) increased with increasing temperatures, with ER increasing faster than GER Hence, short term carbon loss from the ecosystem accelerated with raised temperatures. Temperature sensitivity of the ecosystem was dependent on the soil moisture level, shown by differing Q(10) values of both GEP and ER at different soil moisture levels. It is therefore highly important to take soil moisture levels into consideration when evaluating responses of ecosystem carbon balance to changes in temperature. The greatest C fixation took place via the two most dominant species of the ecosystem, Vaccinium uliginosum and Empetrum hermaphroditum, with the former being responsible for the different size of C fixation at the three moisture levels.

KW - soil respiration

KW - soil moisture

KW - dry tundra

KW - Arctic

KW - carbon flux

KW - temperature sensitivity

U2 - 10.1007/s10533-003-0855-2

DO - 10.1007/s10533-003-0855-2

M3 - Article

VL - 70

SP - 315

EP - 330

JO - Biogeochemistry

JF - Biogeochemistry

SN - 1573-515X

IS - 3

ER -