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

• Published in: Biogeosciences Vol. 10; no. 2; pp. 733 - 752
• Main Authors: Achat, D. L, Bakker, M. R, Augusto, L, Derrien, D, Gallegos, N, Lashchinskiy, N, Milin, S, Nikitich, P, Raudina, T, Rusalimova, O, Zeller, B, Barsukov, P
• Format: Journal Article
• Language: English
• Published: Katlenburg-Lindau Copernicus GmbH 04.02.2013; European Geosciences Union; Copernicus Publications
• Subjects: Analysis; Climate change; Ecosystems; Environmental aspects; Environmental Sciences; Life Sciences; Soil microbiology; Soils; Russia, Siberia
• ISSN: 1726-4189; 1726-4170; 1726-4189
• DOI: 10.5194/bg-10-733-2013

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.