Contrasting immediate impact of prescribed fires and experimental summer fires on soil organic matter quality and microbial properties in the forest floor and mineral soil in Mediterranean black pine forest.

Prescribed fire (PB) is used to achieve ecological objectives and to reduce fuel hazard thus limiting detrimental impacts of wildfire and appropriate selection of prescription window is critical for these goals. Operational use of PB in the Mediterranean forest is scarce and information about its effects on soil remains incomplete. This study for the first time i) compared the immediate impact of spring and autumn PB and experimental summer fire on key properties of forest floor and mineral topsoil in Mediterranean black pine forest, and ii) assessed the capacity of PB to reduce fuel, with limited immediate impacts on soil.

Effect of repeated soil heating at different temperatures on microbial activity in two burned soils.

The effect of fire severity and recurrence on the recovery of enzymatic activities (β-glucosidase, urease, acid phosphatase) and bacterial activity was monitored. Unburned and burned soil samples from soil affected by a high severity wildfire and by a low severity experimental fire were subjected in laboratory to a temperature gradient to simulate different fire severities. These samples were subjected to a second laboratory heat treatment to simulate the effect of recurrence.

Burning season and vegetation coverage influenced the community-level physiological profile of Mediterranean mixed-mesogean pine forest soils.

Knowledge of forest soil ecology is necessary to assess vulnerability to disturbances, such as wildfires, and improve its microbial diversity and functional value. Soil microbiota play an important role in forest soil processes and are a key driver of postfire recovery, but they are very vulnerable to heat. According to future scenarios for climate and land-use change, fire regimes will undergo transformations in semiarid terrestrial ecosystems, mainly in the Mediterranean Basin.

Key factors controlling microbial community responses after a fire: Importance of severity and recurrence.

Wildfires are a major problem in Mediterranean forest ecosystems, affecting the same area year after year. Their severity is increasing, partly due to climate change and hence, every now and then, virulent fires of high severity spread ravage this region. The aim of this study was to evaluate the influence of fire regime (recurrence, severity) in soil microbial community structure analyzing the phospholipid fatty acid (PLFA) and the microbial functional diversity assessing the level physiological profiling technique (CLPP).

Soil organic matter and phosphorus dynamics after low intensity prescribed burning in forests and shrubland.

Various different factors have led to the accumulation of biomass in forest soils in the Mediterranean-climate region in the last few decades, thus exacerbating the effects of wildfires. Although prescribed burning is used to decrease the fuel load and reduce the currency of mega-wildfires, the impacts on soil organic matter (SOM) and nutrient cycling, and therefore on forest ecosystem sustainability, are uncertain. The present study was designed to cover a range of conditions and therefore to assess the variability in the responses in similar geographical areas.