Seasonal changes in organic carbon content in post-arable forest soils

Abstract

Abstract The purpose of this work is to determine seasonal changes in the organic carbon content in the mineral topsoil horizon of the Dystric Brunic Arenosols currently used as forest. In addition, the influence of forest age on the soil organic carbon (SOC) content in the A horizon was analyzed. The paper presents the results of studies on temporal changes in the SOC content in the mineral surface horizon of 55-year-old (Sk2) and 13-year-old forest (Sk5) in 2013 and 2014. Soil samples were collected from A horizon once a month between April 2013 and March 2015. Based on the conducted studies, clear seasonal differentiation of the SOC content was observed. Higher contents of SOC in the A horizon of the analyzed soils occurred in the autumn and winter months, and were lower in spring and summer. For Sk2 soil, higher SOC values were observed in autumn and then in winter, which on average were 11.08 g·kg−1 and 9.61 g·kg−1 respectively, while lower in spring and summer (8.85 g·kg−1 and 8.83 g·kg–1 respectively). Also in the mineral topsoil horizon of Sk5 soil, higher SOC contents were recorded in autumn and winter (8.07 g·kg−1 and 7.27 g·kg−1 respectively), and lower in spring and summer (6.19 g·kg−1 and 6.57 g·kg−1 respectively). The periodicity of SOC content in plots studied was related to the seasonality of precipitation and temperature. The research also showed that the age of the forest stand influences significantly the content of organic carbon in the A horizon. Higher content of SOC was observed in the A horizon of the 55 years old forest stand (average 9.69 g·kg−1) than on the 13 years old (7.02 g·kg−1).