Temperature effect on maintenance and growth respiration coefficients of young, field-grown hinoki cypress (Chamaecyparis obtusa)

Respiration measurements were made on the entire aboveground parts of young, field-grown hinoki cypress (Chamaecyparis obtusa) trees at monthly intervals over a 5-year period, to examine the effect of temperature on maintenance and growth respiration coefficients. The respiration rate of the trees was grouped on a monthly basis and then partitioned into maintenance and growth components. The maintenance respiration coefficient increased exponentially with air temperature. The maintenance respiration coefficient at a temperature of 0 degrees C and its Q(10) value were 0.205 mmol CO2 g(-1) d.w. month(-1) and 1.81, respectively The growth respiration coefficient, which was virtually independent of temperature, had a mean value of 38.06 +/- 1.95 (SE) mmol CO2 g(-1) d.w. The growth rate increased exponentially with increasing temperature up to a peak at around 18 degrees C, and thereafter declined, thereby resulting in the growth respiration rats bring increasingly less sensitive to increasing air temperature. The reported decreases in the Q(10) value of total respiration with increasing air temperature is due to the way in which the growth component of respiration responds to temperature.