Seasonal influences on bacterial community dynamics in Mediterranean pyrophytic ecosystems

Cistus ladanifer scrublands are one of the most characteristic Mediterranean ecosystems. However, these pyrophytic scrublands, are severely affected by wildfires. To reduce this threat, fire prevention management practices are needed to protect these ecosystems. The aim of this study was to determine the effects of management treatments on bacterial richness, abundance and community composition over the time. Plots were stablished in three different stands with different site histories: (a) an eight-year-old stand regenerated after a wildfire; (b) an eight-year-old stand that developed after the total clearing of the previous stand; and (c) a 20-year-old stand that developed following a wildfire. Considered management treatments were total clearing, 50% clearing and controlled burning. Our results revealed that bacterial richness, abundance and community composition were affected by site history and differed among seasons, whereas fire prevention treatments had only a minor effect and did not significantly affect bacterial richness. An absence the management effects suggest that active management does not affect bacterial communities dramatically, supporting active management to rejuvenate senescent stands and to create clearings in young stands. Thus, these practices could reduce the probability of forest wildfires increasing bacterial richness and abundance and growing habitat heterogeneity.