Respiration of Forest Trees (I)

Measurement of Respiration in Pinus densi-thunbergii UYEKI by an Enclosed Standing Tree Method

Abstract

Respiration rates of the above ground part of 7 to 11 year-old (as of 1978) Pinus densi-thunbergii UYEKI planted on the campus of Nagoya University were measured at monthly intervals from October 1977 to March 1979. For the measurements, the enclosed standing tree method, utilizing a plastic bag, was adopted. The respiration rates were
high at twilight and gradually declined toward midnight. The thermal coefficients of the respiration rate were estimated to be 1.14_??_1.79 in the higher temperature
months of April to October and 4.27_??_9.81 in the lower temperature months of November to March. The seasonal trend of the respiration rates largely followed that of the air temperature except in August. The respiration rates were correlated with tree size in power-form function and were directly proportional to its dry weight. The annual amount of respiration rate of the above ground portion in the stand was estimated to be 9.22t CO₂/ha yr or 5.66t dry matter/ha yr.
Methodological aspects, short term and seasonal changes in the respiration rate, tree size dependency of the respiration rate, and the interrelationship among the annual respiration loss, biomass, and biomass increment in the entire stand were discussed.