Characteristics of Atmospheric Carbon Dioxide Concentration Distribution in a Hillside Tea Garden

Abstract

The aim of this study is to clarify the distribution of atmospheric CO2 concentrations in a hiliside tea garden called “Ono tea garden” located in Ube City, Yamaguchi Prefecture. Observations were made at the top, middle and lowest points of the eastern slope in the garden, and we measured micrometeorological factors and atmospheric CO2 concentrations over the tea canopy. From observational results we found the following principal characteristics of CO2 distribution: the CO2 concentration changed with time, affectedby photosynthesis or respiration of tea plants. Interestingly, the concentration was higher at the lowest point of the slope during the night. This phenomenon could be caused by advection from the surroundings produced by the downward current along the slope. Vertical distributions of CO2 concentration were also affected by photosynthesis or respiration of the tea plants, in a similar way to those observed over the flat field. But during the night the shape of the vertical CO2 distributions differed from those of the flat field. Namely, vertical CO2 distributions in the hillside tea garden could have two peaks of concentration, and it could be affected by micrometeorological conditions such as air stability, intensity of vertical shear with downward currents along the slope.