CARBON FLUXES IN TWO SUCCESSIONAL STAGES OF VEGETATION IN THE PODGORSKI KRAS.

Research site represents karst grassland and different stages of secondary succession, occasionally affected from forest fires. It is located on karst plateau close to Podgorje village in the sub-mediterranean region of south-west Slovenia. The site is equipped with two Eddy Covariance towers which measure the carbon fluxes in two successional stages of vegetation. The area has undergone major human influences due to its position at the transition between the Mediterranean and central Europe. In fact, agricultural practices, such as overgrazing in the past centuries, led to pronounced destruction of the vegetation cover, causing severe soil erosion and resulting into a stony and bare landscape. However a succession is taking place and different vegetation types, ranging from grasslands to secondary oak forests, are now present. The bedrock is mainly composed of Paleocene and Eocene limestone. The chemical weathering known as karst phenomena led to the formation of Leptosols and Cambisols, which represent insoluble fractions of carbonates. As a result, the soil is superficial, with depths ranging from 0 cm to several decimeters in soil pockets between rocks. The organic matter represents about 12–15% of the topsoil. The climate is referred to as sub-mediterranean, with a mean annual temperature of 10.5 °C, a mean daily temperature of 1.8 °C and 19.9 °C in January and June respectively, and an average annual precipitation around 1370 mm. The growing season ranges from March or April to October.