Expected impacts of climate change on fuel status in Mediterranean shrublands

Wildland fires represent an important disturbance for ecosystems in the Mediterranean Basin. At vegetation level, the water content of fuel plays a crucial role in determining the wildland fire danger. Evergreen sclerophyll shrubland represents an important component of both Mediterranean vegetation community and understorey vegetation. In addition, shrublands constitute the surface fuels primarily responsible for the ignition and the spread of wildland fires in Mediterranean areas. According to the recent projections of future climate in southern Europe, changes in temperature, precipitation and extreme events are expected. In particular, the largest warming is likely to be in the Mediterranean area during the summer season with the maximum summer temperature increase in both southern and central Europe. Annual precipitation is very likely to decrease in most of the Mediterranean Basin area with decreasing rainy days and increasing risk of summer drought in both central and southern Europe. In this context, a more prolonged drought season could influence fuel moisture content and, consequently, the length of critical periods of high ignition danger for Mediterranean ecosystems. The main aim of this work is to identify useful tools to forecast impacts of expected climate change on fuel status in Mediterranean shrublands.

The study was carried out in North Western Sardinia (Italy) in two phases. During the first step, moisture content of dead fuel (1 hour and 10 hours fractions) was determined periodically during three consecutive years on several Mediterranean shrub species. In addition, meteorological variables and temporal patterns of moisture content estimated using humidity sensors were also recorded. Data were used to determine the accuracy of two well-known meteorological moisture codes, the Canadian Fine Fuels Moisture Code and the US 10-h.

During the second phase, the potential climate change impact on fuel status and ignition danger season in Mediterranean Basin shrubland was simulated using the meteorological codes and future climate scenarios at local scale derived from an advanced high resolution regional climate model.

The results reported here show that future climate projections will greatly affect the duration of the drought season determining changes in fuel moisture dynamics and, consequently, a general increase of fire danger in the Mediterranean area.