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

[摘要] The Siberian forest is a tremendous repository ofterrestrial 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, buttree roots may mine the soil deep to increase access to mineral P. Improvedunderstanding and quantification of the processes controlling P availabilityin surface and deep soil layers of Siberian forest ecosystems are thusrequired. The objectives of the present study were to (1) evaluate P statusof surface and deep soil horizons from different forest plots insouthwestern Siberia and (2) assess the effects of physicochemical soilproperties, microbiological activity and decomposition processes on soil Pfractions and availability. Results revealed high concentrations of total P(879–1042 mg kg⁻¹ in the surface mineral soils) and plant-availablephosphate ions. In addition, plant-available phosphate ions accumulated inthe subsoil, suggesting that deeper root systems may mine sufficientavailable P for the trees and the potentially enhanced growth and Csequestration, may not be P-limited. Because the proportions of total organicP were large in the surface soil layers (47–56% of total P), weconcluded that decomposition processes may play a significant role in Pavailability. However, microbiological activity and decomposition processesvaried between the study plots and higher microbiological activity resultedin smaller organic P fractions and consequently larger available inorganic Pfractions. In the studied Siberian soils, P availability was also controlledby the physicochemical soil properties, namely Al and Fe oxides and soil pH.

[学科分类] 地球化学与岩石