Prescribed burning versus mechanical treatments as shrubland management options in NW Spain: Mid-term soil microbial response

Intensive management has been proposed as a method of preserving European heathland ecosystems, many of which have undergone a process of decline in the last decades. Non-intensive management techniques such as prescribed burning, shrub clearing and mechanical shredding could also play a role in heathland preservation and simultaneously be used to reduce fuel accumulation and thus minimize fire hazard in fire prone areas. However, information about the specific effects of these practices on soil microbiota is particularly scarce. This study examines the effects of the above-mentioned treatments on microbial properties in the soil organic layer (O horizon) and the upper two cm of mineral soil (as soil quality indicators) in shrubland ecosystems in NW Spain. The microbial parameters were measured periodically between spring 2010 (before treatments) and spring 2014 (4 years later). The most noticeable responses in microbial parameters were observed in the soil organic layer. Prescribed burning induced more pronounced changes than mechanical shredding and clearing. Although most of the changes in microbial parameters were ephemeral, some of them lasted three years.