Twin studies in Chinese closed controlled ecosystem with humans: The effect of elevated CO2 disturbance on gas exchange characteristics

Abstract

Elevated atmospheric CO2 has been shown to rapidly alter plant physiology and ecosystem productivity, but contemporary ecological responses to increased CO2 have yet to be studied in a controlled closed ecosystem with humans. To test this concept, at an integrated ground-based Bioregenerative Life Support System (BLSS) named Lunar Palace-1, we tested elevated CO2 effects on gas exchange characteristics in an experiment involving humans. During the whole experimental process, researchers monitored CO2 and O2 concentrations in different plant growth and human occupied cabins on a real time basis. By turning off lighting and air ventilation system, elevated CO2 effects were measured in plant chamber and overall facility during a 1h period. The results indicated that elevated CO2 had variable effects on plant photosynthetic and respiration rates. Photosynthesis in most plants is typically not saturated with respect to carbon dioxide at 400ppm. Elevated CO2 has inhibitory effects on plant respiration. Photosynthesis is strengthened and respiration is reduced in a closed artificial ecosystem were demonstrated under high levels of CO2. Our findings in this closed ecosystem may serve as key baseline design data for larger, long-term and higher degree of closure BLSS integration experiment planned for the near future.