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Sequestration and turnover of plant‐ and microbially derived sugars in a temperate grassland soil during 7 years exposed to elevated atmospheric pCO 2
Author(s) -
BOCK MICHAEL,
GLASER BRUNO,
MILLAR NEVILLE
Publication year - 2007
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.1365-2486.2006.01303.x
Subject(s) - environmental chemistry , chemistry , organic matter , soil carbon , agronomy , mineralization (soil science) , carbon sequestration , silt , soil organic matter , lolium perenne , terrestrial ecosystem , carbon dioxide , soil water , ecosystem , environmental science , ecology , soil science , perennial plant , biology , paleontology , organic chemistry
Temperate grasslands contribute about 20% to the global terrestrial carbon (C) budget with sugars contributing 10–50% to this soil C pool. Whether the observed increase of the atmospheric CO 2 concentration (pCO 2 ) leads to additional C sequestration into these ecosystems or enhanced mineralization of soil organic matter (SOM) is still unclear. Therefore, the aim of the presented study was to investigate the impact of elevated atmospheric pCO 2 on C sequestration and turnover of plant‐ (arabinose and xylose) and microbially derived (fucose, rhamnose, galactose, mannose) sugars in soil, representing a labile SOM pool. The study was carried out at the Swiss Free Air Carbon Dioxide Enrichment (FACE) experiment near Zurich. For 7 years, Lolium perenne swards were exposed to ambient and elevated pCO 2 (36 and 60 Pa, respectively). The additional CO 2 in the FACE plots was depleted in 13 C compared with ambient plots, so that ‘new’ (<7 years) C inputs could be determined by means of compound‐specific stable isotope analysis ( 13 C : 12 C). Samples were fractionated into clay, silt, fine sand and coarse sand, which yielded relatively stable and labile SOM pools with different turnover rates. Total sugar sequestration into bulk soil after 7 years of exposure to elevated pCO 2 was about 28% compared with the control plots. In both ambient and elevated plots, total sugar concentrations in particle size fractions increased in the order sand