Respiratory Behaviour of Young Hinoki Cypress ( Chamaecyparis obtusa ) Trees under Field Conditions

Author： Adu-Bredu S. Yokota T. Hagihara A.

ISSN： 0305-7364

Source： Annals of Botany, Vol.77, Iss.6, 1996-06, pp. : 623-628

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Abstract

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, 0.0352, 0.0211, 0.0316 and 0.0200g CO 2 g month , in decreasing order of tree size. The maintenance coefficients of the stressed (i.e. 0.0211g CO 2 g month ) and suppressed (i.e. 0.0200g CO 2 g month ) 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 1.64g CO 2 g , in decreasing order of tree size. The growth coefficient of the stressed tree (i.e. 1.80g CO 2 g ) was the largest followed by that of the smallest and suppressed tree (i.e. 1.64g CO 2 g ), 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.