Chin J Plant Ecol ›› 2007, Vol. 31 ›› Issue (3): 386-393.DOI: 10.17521/cjpe.2007.0047

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EFFECTS OF ELEVATED CO2 CONCENTRATIONS ON SOIL MICROBIAL RESPIRATION AND ROOT/RHIZOSPHERE RESPIRATION IN FOREST SOIL

ZHOU Yu-Mei1(), HAN Shi-Jie1,*(), ZHENG Jun-Qiang1, XIN Li-Hua2, ZHANG Hai-Sen1   

  1. 1Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang 110016, China
    2Shenyang Agricultural University, Shenyang 110061, China
  • Received:2006-06-19 Accepted:2006-11-14 Online:2007-06-19 Published:2007-05-30
  • Contact: HAN Shi-Jie

Abstract:

Two main components of soil respiration, i.e., root/rhizosphere and microbial respirations, respond differently to elevated atmospheric CO2 concentrations both in mechanism and sensitivity because they have different substrates, derived from plant and soil organic matter, respectively. To model the carbon cycle and predict carbon source/sink of forest ecosystems, we must first understand the relative contributions of root/rhizosphere and microbial respirations to total soil respiration under elevated CO2 concentrations. Root/rhizosphere and soil microbial respirations have been shown to increase, decrease and remain unchanged under elevated CO2 concentrations. A significantly positive relationship between root biomass and root/rhizosphere respiration has been found. Fine roots respond more strongly to elevated CO2 concentrations than coarse roots. Evidence suggests that soil microbial respiration is highly variable and uncertain under elevated CO2 concentrations. Microbial biomass and activity are related or unrelated to rates of microbial respiration. Because substrate availability drives microbial metabolism in soil, it is likely that much of the variability in microbial respiration resulted from differences in the response of root growth to elevated CO2 and subsequent change in substrate production. Biotic and abiotic factors influencing soil respiration were found to affect both root/rhizosphere and microbial respirations.

Key words: elevated CO2 concentrations, soil respiration, rhizosphere, soil microorganism