Seasonal variation in the size-dependent respiration of mangroves Kandelia obovata

Abstract

Despite the potential importance of mangrove forests in carbon cycling and coastal ecology, information on mangrove respiration is scanty. Aboveground nighttime respiration of mangrove Kandelia obovata trees at the northernmost limit of their distribution was measured monthly throughout a year to investigate size-dependence and seasonal variation in respiration. Six sample trees of different sizes were selected from a completely closed canopy stand. Respiration rate (r) of K. obovata trees at a monthly mean temperature increased with increasing mass (m). This tendency was described by means of the power function r = fmh, where f is the multiplying coefficient and h is the scaling exponent. The exponent values ranged from 0.723 to 1.085. In the cool winter (dormant season), the exponent h was close to 1.0, while in the warm summer (growing season) the exponent was closer to 3/4. Respiration varies more between seasons in small-sized trees than in large-sized trees. The relative increase in respiration from the winter dormant season to the summer growing season was large in the small-sized trees compared with that in the large-sized trees. The variation in respiration between the 2 seasons is explained on the basis of theories about resource harvesting and transport. Separation of summer respiration into growth and maintenance components is suggested to better understand the dependence of respiration on size and temperature. © Inter-Research 2010.