Variations in the live biomass and carbon pools of Abies georgei along an elevation gradient on the Tibetan Plateau, China

The spatial distribution of montane forest biomass and C pools along altitudinal gradients and the role of the climate gradient on the Tibetan Plateau are not well-understood. To determine how live biomass and C pools in montane forests vary along an elevation gradient, the biomass and C content of fir trees (Abies georgei), the most widespread forest type on the Tibetan Plateau, were measured from 3100 m asl to 4400 m asl. The total live biomass of the forest nonlinearly declined by 66.2% with the elevation gradient, with most of the biomass reduction (covering almost 94% of the total reduction) occurring at altitudes lower than 3400 m asl and at altitudes above 3900 m asl, and the C concentration of the aboveground components (stems, leaves and branches) of A. georgei were positively correlated with the biomass variation along an elevation gradient. The total C pool of A. georgei (stand and root C) decreased from 259.73 +/- 11.75 t C/ha at 3100 m asl to 87.29 +/- 8.21 t C/ha at 4300 m asl, whereas the biomass C pool allocation in the roots increased by 2.5% at the same altitude. A possible explanation for these marked shifts in the biomass and C allocation from above to belowground along an increasing elevation gradient is discussed, including the limitation of the N supply and the effect of lower temperatures. The annual air temperature and precipitation were positively correlated with the live biomass and C stocks along an elevation gradient. The live biomass C is allocated more to aboveground components with increasing temperature and precipitation. (C) 2014 Elsevier B.V. All rights reserved.