Plant species influence on soil microbial short-term response after fire simulation

Plant species can influence fire intensity and severity causing different immediate and long-term responses on the soil microbial community. The main objective of this work was to determine the role of two representative Mediterranean plant species as soil organic matter sources, and to identify their influence on microbial response before and after heat exposure. A laboratory heating experiment (300 A degrees C for 20 min) was performed using soil collected under Pinus hallepensis (PIN) and Quercus coccifera (KER). Dried plant material was added before heating for a total of six different treatments: non-heated control samples amended with the original plant material (PIN0 and KER0); PIN samples heated with pine (PINp) or kermes oak litter (PINk); KER samples heated with kermes oak (KERk) or pine litter (KERp). Heated soils were inoculated with the original fresh soil and different microbial parameters related to abundance, activity and possible changes in microbial community composition and chemical soil parameters that could be conditioning microbial response were measured for 28 days after inoculation. The effect of heating on the soil microbial parameters studied was influenced to a small extent by the plant species providing fuel, being evident in soil samples taken under pine influence. Nevertheless heating effect showed marked differences when plant species influence on soil origin was analyzed. In general, samples taken under pine appear to be more negatively affected by heating treatment than samples collected under kermes oak, highlighting the importance of vegetation as a fresh organic matter source in soil ecosystems before and after fire.