Annals of Botany 77: 623-628, 1996
© 1996 Annals of Botany Company
Respiratory Behaviour of Young Hinoki Cypress (Chamaecyparis obtusa) Trees under Field Conditions
Forest Ecophysiology Laboratory, Forest Sciences Division, School of Agricultural Sciences, Nagoya University Nagoya 464-01, Japan
* Present address: Global Environment Research Division, National Institute for Environmental Studies, Onogawa 16-2, Tsukuba, Ibaraki 305, Japan.
Received: 28 July 1995 Accepted: 4 December 1995
Night-time respiration rates of aerial parts of six sample trees in a 9-year-old hinoki cypress [Chamaecyparis obtusa (Sieb. et Zucc.) Endl.] stand were measured at monthly intervals over a 1-year period, by an enclosed whole-tree method. When the relationships between annual respiration rate and mean phytomass, and between annual respiration rate and annual phytomass increment were examined, one sample tree, which was under stress, did not follow the trend of the rest, indicating that its lower respiration rate did not correspond to its size because of its negligible phytomass increment. Respiration was partitioned into maintenance and growth respiration to explain this phenomenon. The maintenance coefficients were 0·0345,0·0373, 00352,0·0211, 0·0316 and 00200 g CO2 g–1 month–1, in decreasing order of tree size. The maintenance coefficients of the stressed (i.e. 00211 g CO2 g–1 month–1) and suppressed (i.e. 0·0200 g CO2 g–1 month–1) trees were similar and smaller than those of the rest which were larger and alike, indicating that stress and suppression reduced the coefficient. The growth coefficients were 1·45, 1·51, 1·28, 1·80, 1·45 and 1·64 g CO2 g–1, in decreasing order of tree size. The growth coefficient of the stressed tree (i.e. 1·80 g CO2 g–1) was the largest followed by that of the smallest and suppressed tree (i.e. 1·64 g CO2 g–1), suggesting that stress and suppression reduced the efficiency of conversion of substrate into new structural phytomass. The stressed tree respired mainly to maintain itself. The respiratory behaviour of the sample trees, including the stressed tree, was compatible with the concept of growth and maintenance respiration.
Chamaecyparis obtusa, growth respiration, hinoki cypress, maintenance respiration, phytomass, phytomass increment, size dependence, stressed tree, suppressed tree