Soil respiration and net primary productivity in perennial grass and desert shrub ecosystems at the Ordos Plateau of Inner Mongolia, China

In arid lands, the shifts in dominant plant types from grasses to shrubs can significantly alter the ecosystem function and biogeochemistry cycles. However, the magnitude of these alterations and its inherent mechanisms are still poorly understood. In this study, we measured soil respiration and NPP over two growing seasons in 2006-2007 in the co-occurring perennial grass and desert shrub ecosystems at the Ordos Plateau of Inner Mongolia, China. Over the two growing seasons, the desert shrub site presented higher aboveground biomass and NPP while lower soil respiration relative to the grass site (p < 0.05). In this paper, we can not determine that whether vegetation conversion or soil texture change drive the site difference in soil respiration because we did not control for soil texture. We suppose that the site difference in pulse response of soil respiration might play an essential role in regulating this soil respiration gap. In all the growing seasons, surface soil moisture (0-10 cm) was identified as the major driver of soil respiration at both sites. Compared to the linear soil moisture model, the integrated model incorporating both surface soil moisture and air temperature was performed better in predicting the dynamics of soil respiration. (C) 2010 Elsevier Ltd. All rights reserved.