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Partitioning pattern of carbon flux in a Kobresia grassland on the Qinghai‐Tibetan Plateau revealed by field 13 C pulse‐labeling
Author(s) -
WU YIBO,
TAN HONGCHAO,
DENG YONGCUI,
WU JING,
XU XINGLIANG,
WANG YANFEN,
TANG YANHONG,
HIGASHI TERUO,
CUI XIAOYONG
Publication year - 2010
Publication title -
global change biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 4.146
H-Index - 255
eISSN - 1365-2486
pISSN - 1354-1013
DOI - 10.1111/j.1365-2486.2009.02069.x
Subject(s) - shoot , growing season , photosynthesis , carbon fibers , ecosystem , carbon cycle , biomass (ecology) , botany , soil carbon , soil respiration , plateau (mathematics) , respiration , agronomy , terrestrial ecosystem , biology , soil water , ecology , mathematics , mathematical analysis , materials science , composite number , composite material
Characterizing the carbon turnover in terrestrial ecosystems is critical for understanding and predicting carbon dynamics in ecosystems. We used in situ 13 C pulse labeling to track photosynthetic carbon fluxes from shoot to roots and to soil in a Kobresia humilis meadow on the Qinghai‐Tibet Plateau. We found that about 36.7% of labeled carbon was translocated out from the shoots within the first 24 h after photosynthetic uptake. This is equivalent to 66.1% of total 13 C moving out from the shoot during the 32‐day chase period, indicating a rapid and large translocation of newly fixed carbon to belowground parts in these alpine plants. 58.7% of the assimilated 13 C was transferred belowground. At the end of the chase phase, 30.9% was retained in living roots, 3.4% in dead roots, 17.2% lost as belowground respiration and 7.3% remained in the soil. In the four carbon pools (i.e., shoots, living roots, dead roots, and soil pools), living roots consistently had the highest proportion of 13 C in the plant–soil system during the 32 days. Based on the 13 C partitioning pattern and biomass production, we estimate a total of 4930 kg C ha −1 was allocated belowground during the vegetation growth season in this alpine meadow. Of this, roots accumulated 2868 kg C ha −1 and soils accumulated 613 kg C ha −1 . This study suggests that carbon storage in belowground carbon pools plays the most important role in carbon cycles in the alpine meadow.