Increase in the CO2 exchange rate of leaves of Ilex rotunda with elevated atmospheric CO2 concentration in an urban canyon

摘要

The atmospheric CO2 concentration in an urban canyon in Fukuoka city, Japan, during August 1997 was about 30μmol/mol higher than that in the suburbs. When fully exposed to sunlight in situ, the rate of photosynthesis in single leaves of I. rotundaplanted in the urban canyon was higher when the atmospheric CO2 concentration was elevated. A model (based on biochemistry) was able to predict the in situ rate of photosynthesis well. The model also predicted an increase in the daily CO2 exchange rate for leaves in the urban canyon with an increase in atmospheric CO2 concentration. However, in situ such an increase in the daily CO2 exchange rate may be offset by diminished sunlight, a higher air temperature and a lower relative humidity. Thus, the daily CO2 exchange rate predicted using the model based solely on the environmental conditions prevailing in the urban canyon was lower than that predicted based only on environmental factors found in the suburbs.