Whole-stand estimates of woody tissue respiration in a northern mixed hardwood forest: comparisons between sepcies and across size classes.

Abstract

The objectives of this study were to model woody stem respiration rates in a temperate deciduous forest. Previous studies have shown stem CO2 efflux to increase exponentially with temperature (Ryan et al., 1995; Edwards and Hanson, 1996). This study modeled the respiration-temperature relationship for woody stems of different species in an intensely monitored Northern Michigan mixed hardwood forest. Differences in respiration rates between tree species were examined, as well as between different size classes of tree based on diameter at breast height (DBH). Variability of stem respiration due to sunlight availability was also examined, as well as bole and branch respiration at different heights above ground on individual trees. Species specific respiration regressions against temperature were done, with all respiration rates expresed in terms of tree sapwood volume. After determining the sapwood biomass of the whole stand, these regressions were used to model the total respiration of the site for the months of June, July, and August, 1999. The final modeling equations can be used to determine total respiration of this site over any period of time, provided there is frequent temperature data.