The role of soil-forming processes and changes in land cover in the storage and stabilization of soil organic carbon - preliminary results from the Carpathians (Southern Poland)

The sequestration of carbon in the form of organic compounds in the soil is considered one of the main strategies for mitigating climate change. Mountain ecosystems have a great potential to store soil organic carbon (SOC) due to relatively lower temperatures and higher precipitation, which slow down the rate of organic matter decomposition. However, mountains are also regions particularly vulnerable to changes caused by direct and indirect human activity, in particular climate change and land cover change. All these changes have an impact on soil properties and thus on SOC stocks and their stability. One of the changes that has been particularly evident in mountainous regions in recent decades is the rapid succession of forests over grasslands, due to the land abandonment and the effects of global warming. In addition, the soil cover of mountainous regions is characterized by a large natural diversity of soil-forming processes, which is reflected in differences in the SOC sequestration potential. Thus, the aim of this research was to determine the effect of different soil-forming processes compared to different land cover on SOC stock and SOC stability. 
The SOC stock was measured in soils subjected to various soil-forming processes (podzolization, brunification, peat accumulation) and with different land cover (ancient forests, succession forests, meadows) in three similar study areas in the Carpathians (S Poland). The highest SOC stocks in the first 30 cm of soil were found in ancient forests (between 4.2 kg m-1 and 8.8 kg m-1) and the lowest in meadows dominated by tall-grass communities (1.3–2.0 kg m-1). The SOC stock was significantly higher in Podzols than in Cambisols and Histosols; however, most of the soils subjected to podzolization were found in forests. In addition, in mineral soils with contrasting pedogenic pathways (Podzols and Cambisols) soil organic matter fractionation was carried out. The preliminary results indicate that Podzols are characterized by much higher SOC content outside water-stable aggregates and in light fractions (particulate organic matter), which suggests relatively a weaker stability of organic matter in this type of soils than in Cambisols.
This project has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 952327 (HES-GEO) and has been supported by a grant from the Priority Research Area Antropocene (Young Labs) under the Strategic Programme Excellence Initiative at Jagiellonian University.