Soil respiration and soil microbial biomass after fire in a sweet chestnut forest in southern Switzerland

The effects of two fire intensities on soil microbial biomass and soil respiration were measured in a field-scale experiment on a sweet chestnut (Castanea sativa Mill.) forest slope in St. Antonino, southern Switzerland. Low fire intensity on the slope with normal fuel load had no significant effect on soil respiration or microbial biomass. Twenty hours after a higher intensity fire on a slope with double fuel load, soil respiration had increased and remained high for several months. We suggest that this would increase the risk of nutrient outwash from the burnt slope. However, the size of the soil microbial biomass was unchanged or even slightly decreased compared to unburnt control sites. Soil microbial biomass therefore played no significant role in limiting nutrient losses after the fire.