Microbial functional diversity of a shrubland soil experimentally burned and treated with two post-fire stabilization techniques (straw mulch and seeding)

The study examined the effect of two post-fire stabilization treatments (seeding and mulching) on microbial diversity of a shrubland area of Galicia after an experimental fire. The soil was a Leptosol developed over granite with a slope of 38-54% and the soil microbial functional diversity was assessed using Biolog substrate utilization EcoPlates (Biolog Inc., Hayward, CA, USA). Soil samples were taken from the A horizon (0-5 cm depth) at different sampling times over one year after the experimental fire. The results indicated that immediately after the fire there were significant differences in the categorized substrate utilization pattern between the microbial communities of the burnt soil treatments and the corresponding unburnt control. The burned soils exhibited significant higher values for the utilization of carboxylic acids, amino acids, carbohydrates and phenolic compounds, suggesting that the microbial community in the burned soils could be favoured by the increase in available C and nutrients following the experimental fire. These changes in the categorized substrate utilization pattern were attenuated with time; thus, one year after the fire, similar values for utilization of different C sources were observed for all unburned and burnt soils. With respect to post-fire treatments only the mulching showed an effect on the C utilization pattern.