Long-term respiratory cost of maintenance and growth of field-grown young Hinoki cypress (Chamaecyparis obtusa)

Respiration rate of the entire above-ground parts of field-grown 8-year-old hinoki cypress [Chamaecyparis obtusa (Sieb. et Zucc.) Endl.] was measured at monthly intervals over a 5-year period, to evaluate the trend in proportion of maintenance and growth components of respiration with stand development. Representative sample trees were selected for respiration measurements. The annual respiration rates of individual sample trees were combined and partitioned into maintenance and growth components by regressing specific respiration rate on mean relative growth rate. Maintenance and growth respiration coefficients generated in this way were 5.2 mol CO2 kg(-1) year(-1) and 39 mol CO2 kg(-1), which are equivalent to 14.3 mg C kg(-1) C h(-1) (at mean annual air temperature of 15.1 degrees C) and 0.94 kg C kg(-1) C. Considering the maintenance and growth respiration coefficients, and phytomass and phytomass increment of individual trees in the stand, the maintenance and growth respiration rates of the stand were estimated. The proportion of the maintenance respiration increased, whereas that of the growth respiration decreased with stand development, due to decreasing relative growth rate. (C) 1997 Annals of Botany Company.