© 1995 Heron Publishing—Victoria, Canada
Maintenance and growth respiration of the aboveground parts of young field-grown hinoki cypress (Chamaecyparis obtusa)
Taketo Yokota and Akio Hagihara
Laboratory of Forest Ecophysiology, School of Agricultural Sciences, Nagoya University, Nagoya 464-01, Japan / Received March 21, 1994
Summary
Aboveground respiration of five 8-year-old trees of field-grown hinoki cypress (Chamaecyparis obtusa (Sieb. et Zucc.) Endl.) was nondestructively measured at monthly intervals over 1 year with an enclosed standing tree method.
The relationship between monthly specific respiration rate and monthly mean relative growth rate at the individual tree level
was described by a linear equation. During the dormant season, respiration was used mainly for maintenance purposes, whereas
during the growing season, more than 40% of the respiration was used for growth purposes, i.e., 60 to 70% in May. We conclude
that annual maintenance and growth respiration of a tree are directly proportional to the aboveground phytomass and its annual
increment, respectively. The maintenance coefficient was estimated to be 0.504 ± 0.039 (SE) kg kg–1 year–1, indicating that the amount respired for maintaining already existing phytomass was equivalent to about half of the existing
phytomass. The growth coefficient was estimated to be 0.772 ± 0.043 (SE) kg kg–1, indicating that the amount respired for constructing new phytomass was equivalent to about three-fourths of the annual phytomass
increment. The annual stand maintenance and growth respiration were, respectively, 8.8 Mg ha–1 year–1 for an aboveground biomass of 17.4 Mg ha–1 and 5.0 Mg ha–1 year–1 for an annual stand aboveground biomass increment of 6.5 Mg ha–1 year–1. About two-thirds of the total respiration was used to maintain already existing biomass, and about one-third was used to
construct new biomass.
Keywords:
biomass, biomass increment, relative growth rate, specific respiration rate.
