Monday, 17 November 2003
Analysis of fuel type and vegetation structure for fire risk index development
Evergreen sclerophyll shrubland is a prominent feature of Mediterranean Basin. The combination of dense fuels, summer drought, dry summer winds, and anthropic activities contributes to increase fire risk in these. There is a strong demand concerning the evaluation of wildland fire risk. In this context, calculation of fire risk indices for different species of a given zone plays an important role in preventing forest fires. Indices which include statical and dynamic variables are called integrated or advanced. Using variables from different experimental sites located in North Sardinia, Italy, an integrated forest fire index (IFI) was developed to be included into an operational warning system managed by the Regional Weather Service of Sardinia, Italy. The IFI index is based on (1) parameters describing the water status of vegetation, (2) parameters related to fuel type and vegetation structure, (3) micrometeorological or meteorological parameters and (4) topological parameter which is a descriptor of site topography and prevailing synoptical conditions. The knowledge of tree canopy characteristics (number of species, species composition, specific ground cover etc.) is very important because it determines the response of vegetation to any disturbance (fires, drought, global change etc.). In this paper preliminary results regarding the analysis of fuel type and vegetation structure are presented focusing on methodologies used for biomass and vegetation sampling. The study was carried out in two Mediterranean ecosystems located in Sardinia, Italy. The first was in a coastal area and the second in a hill-top area, both dominated by evergreen and semi-deciduous shrubs species. In the coastal experimental area a 12 ha macroplot was selected and a systematic sampling was conducted. In the hill-top area two 15 x 15 m quadrat were selected and each quadrat was divided in 25 subareas. In each quadrat number of species, height of plant and canopy diameter were measured. The number of species, species composition, specific ground cover, biomass, species diversity as woody species richness, competition relationships among the dominant woody species, were calculated. In addition, for the dominant species, in each site the seasonal pattern of fuel moisture content was measured.