Differences in Net Primary Productivity Among Contrasting Habitats in Artemisia ordosica Rangeland of Northern China

Abstract

Artemisia ordosica Krasch. is a semishrub native to the Ordos Plateau of Inner Mongolia, northern China, and forms a unique and dominant vegetation type in the sandland of the region. To determine the variation of productivity in A. ordosica rangeland, we investigated net primary production (NPP), fine root turnover, soil microbial C (Cmic), and soil organic carbon density (SOCd) on sand dunes differing in mobility (i.e., fixed, semifixed, and shifting sand dunes) in Mu Us sandland. We found that, on an area basis, the NPP, SOCd, Cmic, and fine root turnover rates all increased with increasing vegetation cover. However, the ratios of root NPP to total NPP (RMRN) increased with declining vegetation cover. Total NPP varied markedly among habitats and ranged from 18.3 g m-2 yr-1 for communities on the shifting sand dunes to 293.8 g m-2 yr-1 for communities on the fixed sand dunes; whereas the rates of fine root turnover varied from 0.16 yr-1 to 0.54 yr-1. Our study demonstrated that habitat change in sandland has significant impacts on ecosystem productivity by affecting many related aspects of NPP. From the perspective of biomass production, protection of the semifixed dunes from degradation should be taken as a higher priority than trying to convert shifting sand dunes to semifixed sand dunes; whereas conversion of semifixed sand dunes to fixed sand dunes would appear to be a much easier task than restoring shifting sand dunes.