6:15 PM - 7:30 PM
[ACG30-P01] Estimation of carbon cycle in a cool-temperate coniferous forest by continuous monitoring of carbon isotopic ratio
Keywords:forest, carbon cycle, isotope, laser spectrometry, carbon dioxide, respiration
To understand carbon flows in a tree, we carried out in situ 13C pulse-labelling experiments for a mature pine tree (Pinus densiflora, Tree height: 20m) at the FJY site. The experiments were carried out September 2012, December 2012, and July 2013, covering the canopy of the tree by a plastic film chamber and introducing 13CO2 into the labelling chamber. The internal 12CO2 and 13CO2 was monitored by the TDLS to calculate a carbon assimilation by the tree during the labelling experiments. Carbon efflux from a trunk surface were monitored by the TDLS using four closed dynamic trunk chambers installed in different heights (15.5, 11.1, 7.3 and 3.8m height) of the tree. The carbon flow speed were estimated from the arriving time of 13CO2 pulse to the trunk chambers. The pattern of labelled 13CO2 efflux in winter was different from other seasons. The speeds ranged from 0.04 to 0.24 m/hr and relatively slow in winter. The amount of carbon respired from the trunk surface were ranged 14-20% of the assimilated carbon. In winter, the tree respired carbon from relatively upper trunk surface and lower in other seasons.