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

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<sup>−1</sup> 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

Bioavailable Soil Phosphorus Decreases with Increasing Elevation in a Subarctic Tundra Landscape

“…Some organic P compounds have a high affinity for Al and Fe oxides [79]–[81], and soil organic P is often strongly positively related with Al and Fe concentration in organic soils, as seen in both this (Table 3) and other studies [40], [45], [61], [77], [82], [83]. Soil organic P is generally considered to be less prone to sorption than are labile inorganic P forms such as Resin-P [84], but in some humus soils organic P is correlated with Al ox and Fe ox concentration while labile inorganic P is not [40], which is consistent with our findings. A higher organic P sorption capacity in meadow soils could lower P availability indirectly by protecting organic P from microbial mineralization.…”

Influences of evergreen gymnosperm and deciduous angiosperm tree species on the functioning of temperate and boreal forests

“…forest floor + mineral soil) differs between the two types of tree species (Augusto et al, 2003;Vesterdal et al, 2008;Achat et al, 2013;Laganière et al, 2013) as differences in forest floor and mineral soil may offset each other . The production of dead organic matter (foliage and fine roots) and its mineralization, or stabilization, are fairly similar or show, on average, limited differences.…”

Pan-Eurasian Experiment (PEEX): towards a holistic understanding of the feedbacks and interactions in the land–atmosphere–ocean–society continuum in the northern Eurasian region

“…South-western Siberian soils have lately been reported to contain high concentrations of plant-available phosphorus (Achat et al, 2013), which may enhance the carbon sequestration of the ecosystems if they are not too limited by nitrogen. In soils, phosphorus is found mainly in mineral form and bound to the soil parent material such as apatite minerals.…”

“…The amount of phosphorus in the parent material is a defining factor for phosphorus limitation, and the weathering rate determines the amount of phosphorus available for ecosystems. In ecosystems, most of the available phosphorus is in organic forms (Achat et al, 2013;Vitousek et al, 2010). In ecosystems growing on phosphorus-depleted soils, the productivity is more likely to be nitrogen-limited in early successional stages, and gradually shift towards phosphorus limitation as the age of the site increases (Vitousek et al, 2010).…”