Allocation of vegetation biomass across a climate-related gradient in the grasslands of Inner Mongolia

Biomass was measured at 48 undefoliated grassland sites on a 1900-km transect in Inner Mongolia. Above-ground biomass was separated into leaf, stem, flower and fruit, and dead matter, and into the five dominant species at each site. Below-ground biomass was measured to a depth of 30 cm and separated into 10-cm layers. Changes of these biomass components and their ratios were examined in relation to gradients of temperature and precipitation, and to the classification of the sites into five grassland types. Total biomass decreased markedly as site mean annual temperature increased and to a smaller extent as mean annual precipitation decreased. Averaged over all sites 92% of biomass was below ground. The proportion of below-ground biomass increased as temperature decreased, and was least and distributed more deeply in desert grassland. As aridity of the grassland types increased, the proportion of biomass in the first dominant species and in stem relative to leaf tissue increased. The biomass measurements provide baseline data required for monitoring sustainable use of Inner Mongolia grassland for livestock production and its storage of carbon.