Modelling vegetation distribution and net primary production along a precipitation gradient, the Northeast China Transect (NECT)

The Northeast China Transect (NECT) that controlled by precipitation is one of the IGBP Terrestrial Transects in temperate semi-arid regions. The BIOME3 model was ran under the present climate to model the potential vegetation, annual net primary production (NPP) :and leaf;area index (LAI) along tile NECT. The simulated vegetation was basically in good agreement with potential vegetation map based on a numerical comparison of the DeltaV statistic (DeltaV value 0.27). predicted NPP and LAI increase gradually from western desert and steppe, middle grassland and savannas to eastern forests along the increasing precipitation gradient on the NECT. A coupled ocean-atmosphere general circulation model (GCM) including both carbon dioxide and sulphate aerosols was used to drive a double greenhouse gas scenario for tile end of 21(st) Century. The climate change alone produced a reduction in the boreal conifer forest/woodland, temperate conifer forest and short grassland, an increase in the temperate/boreal mixed forest, temperate deciduous broad-leaved forest, moist savannas and tail grassland, with a general pole-ward shift of all Forest biomes and westward shift of all grassland biomcs and disappearance of desert. The inclusion of CO2 physiological effects led to a marked decrease in tile area occupied by most of forests and grasslands except for the temperate deciduous broad-leaved forest with a significant increase in area. Under the condition of changed climate without or with direct effect of doubled CO2, mc:ul annual NPP of biomes was predicted to increase, except for tile boreal conifer forest. Average LAI of forests would increase under only changed climate and both changed climate and effect of doubled CO2. Moreover, LAI for almost of savannas, grassland and steppe would decrease under changed climate without doubled CO2 and increase under changed climate with doubled CO2.