Abstract:As an integrated modeling framework, Integrated Biosphere Simulator (IBIS) is designed to incorporate a range of biophysical, physiological, and ecological processes in terrestrial ecosystems, which likely represents the direction of future research on ecosystem carbon cycling simulation and modeling. In this study, we modified the IBIS-2.6 to simulate the soil respiration (RS), rhizospheric (RR) and heterotrophic (RH) respirations in six typical forests in northeastern China, and validated the simulated values with the measurements. The forests were Mongolian oak (Quercus mongolica Fisch.), aspen-birch (Populous davidiana Dode and Betula platyphylla Suk.), mixed deciduous (no dominant tree species), hardwood (dominated by Fraxinus mandshurica Rupr., Juglans mandshurica Maxim., and Phellodendron amurense Rupr.) forests, Korean pine (Pinus koraiensis Sieb. et Zucc.) and Dahurian larch (Larix gmelinii Rupr.) plantations. The annual fluxes of RS and its components were in a good agreement with the measurements during 2004 and 2005. The biases in RS, RR and RH between the simulated and measured values ranged from -5%-21%, 2%-16%, and -16%-45%, respectively. There was no significant difference between the simulated and measured RS. And the correlation coefficients varied from 0.362 in the mixed deciduous forest to 0.917 in the hardwood forest. The model well represented the seasonal dynamics of the RS for the six forests except for a rapid increasing RS in the late spring or early summer. This study provided a basis for the localized application of IBIS in northeastern China, and suggested that the modified IBIS be suitable for simulating RS at specific forest ecosystem scale.