Accurately partitioning soil respiration into autotrophic and heterotrophic components is important for understanding how ecosystem carbon budgets will respond to climate change. Usually, heterotrophic respiration can be estimated by a linear relationship between soil respiration and root biomass. In this study, however, we found that an exponential relationship was more appropriate than a linear relationship for relating soil respiration to root biomass in a temperate desert steppe in Inner Mongolia, China. (c) 2010 Elsevier Ltd. All rights reserved.