Soil organic matter (SOM) is an important component of the soil. SOM is responsible for availability of nutrients for plants and soil organisms, formation of soil structure and soils water-holding capacity. SOM is made up of organic matter (OM) of plant and animal origin at various stages of decomposition. SOM can be divided into several components called fractions. Fractions differ between each other in their resistance against decomposition. Main SOM fractions are: (1) free floating particulate organic matter (FPOM) and (2) OM bound to soil mineral surfaces in various ways (MAOM) - OH inside macro- and microaggregates and OM bound to silt and clay surfaces (S+C). It is assumed that MAOM fraction becomes C saturated during soil development and no more C can be sequestered in it. Other fractions, particularly FPOM, that are not dominant C storage in the initial stages of soil development become more important in the later stages and amount of C stored in them increases. However, there is scarcity of studies that examine this assumption. In this work I studied the hypothesis that soils in different stage of development will differ in the amount of C stored in different fractions. On top of that, this difference will be affected by the dominant tree species growing on the soil and the effect of tree...
