Mediterranean maquis is an important component of Mediterranean vegetation characterized by high specific and structural heterogeneity and complexity. Flammability of vegetation is influenced by several factors including structural properties, chemical properties, and moisture content. The moisture content of living plants is one of the most critical parameter affecting fire ignition and fire propagation and represents an important variable in fire behaviour modelling. Plant water content variations are related to both environmental conditions and ecophysiological characteristics of plant species. As a consequence, knowledge of seasonal variation of ignitability and vegetation moisture content could contribute to identify critical periods of high fire risk in Mediterranean maquis ecosystems. Time to ignition and live fuel moisture content of four dominant species (Erica scoparia L., Arbutus unedo L., Cistus salvifolius L., and Lavandula stoechas L.) of an inland hilly area located in North Eastern Sardinia, Italy, were measured during the period March-November 2005. Phenological phases of each species, moisture soil content and meteorological variables were also observed during the experimentation. Seasonal patterns of live fuel moisture content were compared with two drought meteorological indices: Drought Code of the Canadian Forest Fire Weather Index System and the Canopy Drought Stress Index. The aims of this work were to evaluate the influence of weather seasonal variations and vegetative and reproductive cycle on live fuel moisture content and to analyze the relations between the seasonal patterns of live fuel moisture content of the studied species and the pattern of two drought meteorological indices. Two typical seasonal patterns of ignitability were identified. Cistus and Lavandula seemed to be strongly sensitive to seasonal changes. They showed a clear increase of fire risk, in term of ignitability, during the drought period. For Arbutus and Erica, the potential fire risk related to ignitability of the live fine fuel appeared constantly high during the year and not strongly dependent to seasons. These patterns were strictly related to the seasonal variation of live fuel moisture content. Significant regression equations were found between plant moisture content and time to ignition. Live fuel moisture seasonal variation of Cistus and Lavandula was also well correlated to values of the drought indices examined. In particular, the Drought Code seemed to be useful to modeling live fuel moisture variation in Mediterranean species that are particularly sensitive to meteorological conditions and characterized by clear and important decrease of moisture content during drought seasons.
Influence of seasonal weather variations and vegetative cycle on live moisture content and ignitability in Mediterranean maquis species
PELLIZZARO G;CESARACCIO C;DUCE P;VENTURA A;ZARA P
2006
Abstract
Mediterranean maquis is an important component of Mediterranean vegetation characterized by high specific and structural heterogeneity and complexity. Flammability of vegetation is influenced by several factors including structural properties, chemical properties, and moisture content. The moisture content of living plants is one of the most critical parameter affecting fire ignition and fire propagation and represents an important variable in fire behaviour modelling. Plant water content variations are related to both environmental conditions and ecophysiological characteristics of plant species. As a consequence, knowledge of seasonal variation of ignitability and vegetation moisture content could contribute to identify critical periods of high fire risk in Mediterranean maquis ecosystems. Time to ignition and live fuel moisture content of four dominant species (Erica scoparia L., Arbutus unedo L., Cistus salvifolius L., and Lavandula stoechas L.) of an inland hilly area located in North Eastern Sardinia, Italy, were measured during the period March-November 2005. Phenological phases of each species, moisture soil content and meteorological variables were also observed during the experimentation. Seasonal patterns of live fuel moisture content were compared with two drought meteorological indices: Drought Code of the Canadian Forest Fire Weather Index System and the Canopy Drought Stress Index. The aims of this work were to evaluate the influence of weather seasonal variations and vegetative and reproductive cycle on live fuel moisture content and to analyze the relations between the seasonal patterns of live fuel moisture content of the studied species and the pattern of two drought meteorological indices. Two typical seasonal patterns of ignitability were identified. Cistus and Lavandula seemed to be strongly sensitive to seasonal changes. They showed a clear increase of fire risk, in term of ignitability, during the drought period. For Arbutus and Erica, the potential fire risk related to ignitability of the live fine fuel appeared constantly high during the year and not strongly dependent to seasons. These patterns were strictly related to the seasonal variation of live fuel moisture content. Significant regression equations were found between plant moisture content and time to ignition. Live fuel moisture seasonal variation of Cistus and Lavandula was also well correlated to values of the drought indices examined. In particular, the Drought Code seemed to be useful to modeling live fuel moisture variation in Mediterranean species that are particularly sensitive to meteorological conditions and characterized by clear and important decrease of moisture content during drought seasons.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.