Phosphorus studies in cold desert ecosystems, specifically those of the Dry Valleys of Antarctica, have been largely confined to hydrologic systems and orthinogenic regions. Though inorganic fractions tend to dominate total soil P in arid systems, the importance of biologic P cycling in warm deserts may also exist in the Dry Valleys. The study of P cycling and P fractions in soils may increase the understanding of habitat ecology relationships in this extreme environment. Our objectives were to 1) examine the soil P fractions in two soils of two Dry Valley sites – Lake Fryxell and Lake Bonney; and 2) using Pearson correlations, compare the relationship among the soil P fractions to other biogeochemical data. Sampling locations were 500, 600, 700, and 800 m upstream from each lake, with samples obtained from along a transect perpendicular to the stream channel at 0, 8, 16, 24, and 32 m. We utilized a sequential inorganic P extraction procedure, analyzing for soluble, Al-bound, Fe-bound, occluded, and Ca-bound P. We also analyzed the soils for labile organic P and biomass P. Our results showed that at both sites the amount of inorganic P concentration increased from soluble to Ca-bound P. Soluble P was less than 1 mg kg-1 at both sites and correlated positively with occluded P and negatively with Fe and Ca-bound P, suggesting soluble P release from the apatite parent material, further bound by the Fe fraction, and ultimately occluded by Fe coatings. Soluble P and occluded P also correlated positively with rotifer population. Al-bound P correlated positively with algal mats and nematode populations. Fe-bound and Ca-bound P correlated positively with tardigrade populations. Our results may indicate a trophic cascade of P is occurring in these systems.
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