Temperature controls ecosystem CO₂ exchange of an alpine meadow on the northeastern Tibetan Plateau

Alpine ecosystems are extremely vulnerable to climate change. To address the potential variability of the responses of alpine ecosystems to climate change, we examined daily CO₂ exchange in relation to major environmental variables. A dataset was obtained from an alpine meadow on the Qinghai-Tibetan...

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Bibliographic Details
Published in:Global change biology 2009, Vol.15 (1), p.221-228
Main Authors: SAITO, MAKOTO, KATO, TOMOMICHI, TANG, YANHONG
Format: Article
Language:English
Subjects:
alpine meadow
Animal and plant ecology
Animal, plant and microbial ecology
Biological and medical sciences
Carbon dioxide
Climate change
CO2 fluxes
CO₂ fluxes
Ecology
eddy covariance method
Fundamental and applied biological sciences. Psychology
General aspects
Light
path analysis
Synecology
Temperature
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Summary:Alpine ecosystems are extremely vulnerable to climate change. To address the potential variability of the responses of alpine ecosystems to climate change, we examined daily CO₂ exchange in relation to major environmental variables. A dataset was obtained from an alpine meadow on the Qinghai-Tibetan Plateau from eddy covariance measurements taken over 3 years (2002-2004). Path analysis showed that soil temperature at 5 cm depth (Ts₅) had the greatest effect on daily variation in ecosystem CO₂ exchange all year around, whereas photosynthetic photon flux density (PPFD) had a high direct effect on daily variation in CO₂ flux during the growing season. The combined effects of temperature and light regimes on net ecosystem CO₂ exchange (NEE) could be clearly categorized into three areas depending on the change in Ts₅: (1) almost no NEE change irrespective of variations in light and temperature when Ts₅ was below 0 °C; (2) an NEE increase (i.e. CO₂ released from the ecosystem) with increasing Ts₅, but little response to variation in light regime when 0 °C[less-than or equal to]Ts₅[less-than or equal to]8 °C; and (3) an NEE decrease with increase in Ts₅ and PPFD when Ts₅ was approximately >8 °C. The highest daily net ecosystem CO₂ uptake was observed under the conditions of daily mean Ts₅ of about 15 °C and daily mean PPFD of about 50 mol m⁻² day⁻¹. The results suggested that temperature is the most critical determinant of CO₂ exchange in this alpine meadow ecosystem and may play an important role in the ecosystem carbon budget under future global warming conditions.
ISSN:1354-1013
1365-2486
DOI:10.1111/j.1365-2486.2008.01713.x