Unearthing the importance of soil development in total phosphorus distribution in China’s mountains

Abstract

Phosphorus (P) as an essential limiting nutrient for primary productivity has a far-reaching impact on ecosystem carbon sequestration. Increasing studies have evaluated the distribution and stock of soil P in natural terrestrial ecosystems, yet few studies explore the large-scale P distribution from the perspective of soil development in the mountain regions. In this study, 1254 soil samples, including organic soils (O horizon), surface mineral soils (A horizon) and parent materials (C horizon), were collected from twenty-nine mountains in China according to soil development conditions. The concentration and stock of total P in the soils were analyzed to decipher the effects of soil development along with other potential drivers on the P distribution. The results showed that total P concentration decreased significantly in the order of O horizon > A horizon > C horizon, whereas total P stock displayed an opposite trend. Spatially, soil total P concentration increased from South to North China and from West to East China, irrespective of soil horizons, whereas total P stock did not present a consistent spatial trend across the soil horizons. Climate, vegetation and atmospheric active nitrogen deposition exhibited negative effects on soil P distribution directly or indirectly by affecting pedogenesis, while soil organic carbon, pH and iron had distinctly positive effects on the P accumulation in specific horizon. The results highlight the importance of soil development on soil total P distribution in mountains, and this process should be considered when evaluating soil P dynamics in the P biogeochemical cycling models.