© 1991 Heron Publishing—Victoria, Canada
Root respiration in Chamaecyparis obtusa trees
Shigeta Mori (1) and Akio Hagihara (2)
1. Shikoku Research Center, Forestry and Forest Product Research Institute, 915 Asakura-Tei, Kochi 780, Japan / 2. Department of Forestry, Nagoya University, Nagoya 464-01, Japan / Received April 17, 1990
Summary
We examined the respiration rate of root segments, which had a constant length in relation to their diameter, from three small
and two large 26-year-old Chamaecyparis obtusa (Siebold & Zucc.) Endl. trees. The dependence of respiration rate on segment diameter was described by a power function with
an exponent of about 1.5, except for the smallest sample tree, for which the exponent was 1.74. Unlike stem segments, root
segments of similar diameter showed similar rates of respiration regardless of the tree from which the root segments had been
taken. On the basis of the power function, we propose a new equation to estimate the total root respiration rate of a tree.
The relationship between root respiration rate per tree and root weight can be expressed by a power function with an exponent
of 1.11. The ratio of the specific respiration rate of stems to that of roots was 0.7 for the three smaller trees, and 1.1
to 1.3 for the two larger trees. In November, the stand respiration rate of roots was estimated to be 0.36 kg CO2 ha–1 h–1 for a root biomass (dry weight) of 28 Mg ha–1.
