© 2005 Heron Publishing—Victoria, Canada
Separating rhizosphere respiration from total soil respiration in two larch plantations in northeastern China
Lifen Jiang (1, 2), Fuchen Shi (3, 4), Bo Li (1), Yiqi Luo (1, 5), Jiquan Chen (1, 6) and Jiakuan Chen (1)
1. Ministry of Education Key Laboratory for Biodiversity Science and Ecological Engineering, Institute of Biodiversity Science,
Fudan University, Shanghai 200433, P.R. China / 2. Key Laboratory of Forest Plant Ecology, Ministry of Education, Northeast Forestry University, Harbin 150040, P.R. China / 3. College of Life Science, Nankai University, Tianjin 300071, P.R. China / 4. Corresponding author (fcshi@nankai.edu.cn) / 5. Department of Botany and Microbiology, University of Oklahoma, Norman, OK 73019, USA / 6. Department of Earth, Ecological and Environmental Sciences, University of Toledo, Toledo, OH 43560, USA / Received May 10, 2004; accepted January 21, 2005; published online July 4, 2005
Summary
The potential capacity of soil to sequester carbon in response to global warming is strongly regulated by the ratio of rhizosphere
respiration to respiration by soil microbial decomposers, because of their different temperature sensitivities. To quantify
relative contributions of rhizosphere respiration to total soil respiration as influenced by forest stand development, we
conducted a trenching study in two larch (Larix gmelini (Rupr.) Rupr.) plantations, aged 17 and 31 years, in northeastern China. Four plots in each plantation were randomly selected
and trenched in early May 2001. Soil surface CO2 effluxes both inside and outside the plots were measured from May 2001 to August 2002. Soil respiration (i.e., the CO2 effluxes outside the trenched plots) varied similarly in the two plantations from 0.8 µmol m–2 s–1 in winter to 6.0 µmol m–2 s–1 in summer. Rhizosphere respiration (i.e., CO2 efflux outside the trenched plots minus that inside the plots) varied from 0.2 to 2.0 µmol m–2 s–1 in the old forest and from 0.3 to 4.0 µmol m–2 s–1 in the young forest over the seasons. Rhizosphere respiration, on average, accounted for 25% of soil respiration in the old
forest and 65% in the young forest. Rhizosphere and soil respiration were significantly correlated with soil temperature but
not with soil water content. We conclude that the role forests play in regulating climate change may depend on their age.
Keywords:
carbon dioxide, forest age, Q10, soil respiration, soil temperature, soil water, trenching method.
