Grassland fire effect on soil organic carbon reservoirs in a semiarid environment

The aim of this work was to investigate the ef- fect of an experimental fire used for grassland management on soil organic carbon (SOC) stocks. The study was carried out on Hyparrhenia hirta (L.)Stapf (Hh) grassland and Am- pelodesmos mauritanicus(Desf.) T. Durand & Schinz (Am) grasslands located in the north of Sicily. Soil samples were collected at 0-5 cm before and after the experimental fire, and SOC was measured. During the grassland fire, soil sur- face temperature was monitored. Biomass of both grasses was analysed in order to determine dry weight and its chem- ical composition. The results showed that SOC varied sig- nificantly with vegetation type, while it is not affected in the short term by grassland fire. Am grassland stored more SOC compared with Hh grassland thanks to lower content in the biomass of the labile carbon pool. No significant difference was observed in SOC before and after fire, which could be caused by several factors: first, in both grassland types the measured soil temperature during fire was low due to thin lit- ter layers; second, in a semiarid environment, a higher min- eralization rate results in a lower soil carbon labile pool; and third, the SOC stored in the finest soil fractions, physically protected, is not affected by fire.