Seasonality of soil biological properties in a poplar plantation growing under elevated atmospheric CO2 |
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| Institution: | 1. Key Laboratory of Forest Ecology and Environment, China''s State Forestry Administration, Research Institute of Forest Ecology, Environment and Protection, Chinese Academy of Forestry, Beijing 100091, China;2. International Joint Research Laboratory for Global Change Ecology, State Key Laboratory of Cotton Biology, College of Life Sciences, Henan University, Kaifeng, Henan 475004, China;3. Division of Forest and Natural Resources, West Virginia University, P.O. Box 6215, Morgantown, WV 26506-6125, USA;4. Dalla Lana School of Public Health, University of Toronto, 155 College Street, Toronto, Ontario M5T 3M7, Canada |
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| Abstract: | Microorganisms are the regulators of decomposition processes occurring in soil, they also constitute a labile fraction of potentially available N. Microbial mineralization and nutrient cycling could be affected through altered plant inputs at elevated CO2. An understanding of microbial biomass and microbial activity in response to belowground processes induced by elevated CO2 is thus crucial in order to predict the long-term response of ecosystems to climatic changes. Microbial biomass, microbial respiration, inorganic N, extractable P and six enzymatic activities related to C, N, P and S cycling (β-glucosidase, cellulase, chitinase, protease, acid phosphatase and arylsulphatase) were investigated in soils of a poplar plantation exposed to elevated CO2. Clones of Populus alba, Populus nigra and Populus x euramericana were grown in six 314 m2 plots treated either with atmospheric (control) or enriched (550 μmol mol?1 CO2) CO2 concentration with FACE technology (free-air CO2 enrichment). Chemical and biochemical parameters were monitored throughout a year in soil samples collected at five sampling dates starting from Autumn 2000 to Autumn 2001.The aim of the present work was: (1) to determine if CO2 enrichment induces modifications to soil microbial pool size and metabolism, (2) to test how the seasonal fluctuations of soil biochemical properties and CO2 level interact, (3) to evaluate if microbial nutrient acquisition activity is changed under elevated CO2.CO2 enrichment significantly affected soil nutrient content and three enzyme activities: acid phosphatase, chitinase and arylsulphatase, indicators of nutrient acquisition activity. Microbial biomass increased by a 16% under elevated CO2. All soil biochemical properties were significantly affected by the temporal variability and the interaction between time and CO2 level significantly influenced β-glucosidase activity and microbial respiration. Data on arylsulphatase and chitinase activity suggest a possible shift of microbial population in favour of fungi induced by the FACE treatment. |
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