The pools of soil organic carbon accumulated in the surface layers of forest soils in the Karkonosze Mountains, SW Poland

Abstract

Differentiation of soil organic carbon (SOC) concentrations and pools in topsoil horizons of forest soils in the Karkonosze Mountains was examined in relation to environmental and human-induced factors, with special focus on altitudinal gradient, related climatic conditions, and a zonality of vegetation. The samples were collected from the forest litter and soil layers 0-10 cm and 10-20 cm, in 621 plots arranged in a regular network of monitoring established in the Karkonosze National Park. The concentrations of SOC were determined in laboratory and used for calculation of SOC pools. Four elevation zones were distinguished for analysis: 500-750 m, 750-1000 m, 1000-1250 m, and >1250 m. The concentrations of SOC in forest litter (38.3-44.1%) showed an insignificant increasing trend with altitude. The concentrations of SOC in the layers 0-10 cm and 10-20 cm, were in a very broad range 0.27-47.6%, thus indicating a high differentiation, and also tended to insignificantly increase along with altitude. The largest share of accumulated SOC pools was proved to be present in the layer 0-10 cm, except for the highest zone >1250 m in which forest litter contains slightly larger amounts of SOC. The pools of SOC accumulated in the 20 cm thick topsoil and forest litter turned out to vary considerably (3.6-58.2 kg·m-2), but the mean values and medians in particular elevation zones fall in a narrow range 10.5-11.9 kg·m-2, close to the values reported from the Alps. The lack of statistical significance of reported tendencies was explained by a monitoring sites-oriented random soil sampling, i.e. in forest stands of various age, species-composition and degradation degree.