Articles | Volume 10, issue 2
Research article
04 Feb 2013
Research article |  | 04 Feb 2013

Phosphorus status of soils from contrasting forested ecosystems in southwestern Siberia: effects of microbiological and physicochemical properties

D. L. Achat, M. R. Bakker, L. Augusto, D. Derrien, N. Gallegos, N. Lashchinskiy, S. Milin, P. Nikitich, T. Raudina, O. Rusalimova, B. Zeller, and P. Barsukov

Abstract. The Siberian forest is a tremendous repository of terrestrial organic carbon (C), which may increase owing to climate change, potential increases in ecosystem productivity and hence C sequestration. Phosphorus (P) availability could limit the C sequestration potential, but tree roots may mine the soil deep to increase access to mineral P. Improved understanding and quantification of the processes controlling P availability in surface and deep soil layers of Siberian forest ecosystems are thus required. The objectives of the present study were to (1) evaluate P status of surface and deep soil horizons from different forest plots in southwestern Siberia and (2) assess the effects of physicochemical soil properties, microbiological activity and decomposition processes on soil P fractions and availability. Results revealed high concentrations of total P (879–1042 mg kg−1 in the surface mineral soils) and plant-available phosphate ions. In addition, plant-available phosphate ions accumulated in the subsoil, suggesting that deeper root systems may mine sufficient available P for the trees and the potentially enhanced growth and C sequestration, may not be P-limited. Because the proportions of total organic P were large in the surface soil layers (47–56% of total P), we concluded that decomposition processes may play a significant role in P availability. However, microbiological activity and decomposition processes varied between the study plots and higher microbiological activity resulted in smaller organic P fractions and consequently larger available inorganic P fractions. In the studied Siberian soils, P availability was also controlled by the physicochemical soil properties, namely Al and Fe oxides and soil pH.

Final-revised paper