Phosphorus Plant Availability and Spatial Variability in Northern Siberian Permafrost-Affected Soils.

As a result of global warming, a shift in vegetation communities in high northern latitude regions can occur. Permafrost thaw influences decomposition rates, availability of nutrients for plants which, in turn, affects the plant community composition by altering environmental conditions. Therefore, research with a focus on the plant-soil interactions (e.g. plant nutrition) in permafrost-affected soils and permafrost-related processes should be conducted to better understand the vegetation dynamics.

In this research, we investigate the influence of permafrost thawing on decomposition rates, spatial variability and availability of phosphorus (P) for plants in permafrost-affected soils at the taiga-tundra boundary ecosystem in the northern Siberia.

The spatially referenced soil samples were taken with a soil corer (50 mm Ø, 34 cm long) at six sites with different active layer depths at the Little Grawijka Creek catchment (67°28.933’ N, 86°25.682’ E), Krasnoyarsk Krai, Russian Federation. In total, 732 soil samples were collected; 122 soil samples per site from two depth increments, 0-10 cm and 10-30 cm. Four P fractions (NaHCO3-Pi; NaOH-Pi; HCl-Pi and H2SO4-Pi fractions) and the total P were measured using the sequential P fractionation method, based on the Hedley et al. (1982) and modified by Kuo (1996), on a continuous-flow analyzer.

Plant nutrient deficiency symptoms were observed at the sites with a shallow active layer (AL) during field work, which were confirmed by lower plant-available P concentrations (6-48 mg/kg) in contrast to the permafrost soils with a deeper AL (5-81 mg/kg). However, the total P concentrations are higher in soils with a shallow AL (209-683 mg/kg) than with a deep AL (170-525 mg/kg). The spatial variability of P decreases on the sites with a deeper AL as a result of permafrost thaw. In conclusion, permafrost thawing increases plant‐available P in permafrost soils leading to an increase in abundance of site-specific vascular species.