Initial Performance Tests of the Closed Geosphere Experiment Facility (CGEF) for Investigation of Ecosystem Carbon Cycles

概要

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The Closed Geosphere Experiment Facility (CGEF), which is highly airtight, is designed to facilitate the investigation of carbon cycles of terrestrial ecosystems. The Geosphere Module has 5.8 m×8.7 m ground area and 11.9 m average height, including 3.1 m soil depth. A wetland ecosystem, with Phragmites australis-dominated vegetation, is scheduled to be introduced into the Geosphere Module. This study characterizes the distribution and variation of the environmental factors of the Geosphere Module (air temperature, light intensity, and air CO2 concentration) that influence the carbon cycles of ecosystems before introducing the wetland ecosystem into the Module. The CGEF can control the average air temperature within 1°C of a set value. The Geosphere Module has heterogeneous light intensity, which decreases from south to north ranged from 54% to 79%. However, the heterogeneity of light conditions caused no serious problem for the growth of P. australis as shown by a pot test over two years. The CO2 separation capacity was sufficient for driving carbon circulation in the Geosphere Module under a condition of maximum CO2 flux from ecosystem respiration of P. australis-dominated vegetation including soils during the night. The initial performance tests showed that CGEF can serve as an experimental means for analyzing ecosystem processes on carbon cycles under controlled conditions.
2010-03-30