Scale-dependent relationships between plant diversity and above-ground biomass in temperate grasslands, south-eastern Mongolia

Relationships between plant diversity (H diversity index) and above-ground biomass (as a surrogate of productivity) were analysed using quadrat data and biomass measures from a precipitation gradient in length of ca. 1000 km in temperate grasslands, south-eastern Mongolia. These analyses were performed both at different ecological scales including taxonomic or functional levels, such as species, community and ecosystem, and at different geographic scales, such as local, landscape and region. Results showed that diversity-productivity relationships differ with different observed ecological and geographical scales in the temperate grasslands of south-eastern Mongolia. In detail, at the individual species level, all relationships between plant diversity and above-ground biomass from local scale to landscape and regional scales are positive and non-linear. At the community level, such relationships are mostly unimodal from landscape to regional scales. At the ecosystem level, the relationship is unimodal at regional scale. A general trend of diversity-productivity relationships in this region seems to be from positive non-linear to unimodal patterns if the scales change from low to high ecological levels and from small to large geographical scales. The unimodal pattern is common in this region.