The relevance of forest fires as a major disturbance factor in vegetation composition, dynamics, and structure is increasing in several ecosystem types. In order to develop adaptation procedures and to strengthen the resilience under future altered fire regimes, it is important to gain a greater understanding of the factors involved in regional fire regimes. This paper evaluates the relative contributions of forest vegetation, land cover, topography, and climate in explaining the fire regime patterns. The analyses were performed independently for 15 territory types delimited according to potential vegetation criteria. Redundancy analysis was used to enable the simultaneous ordination of the response (fire regime) and the explanatory variables. The results reveal important differences among the 15 territories. The explained variance ranged from low to medium depending on the territory. However, for the five territories with greatest fire incidence, the variance explained was more than 39%. The proportion of territory covered by forest (derived from land cover information) was found to be the most relevant variable. Unexpectedly, the type of forest vegetation (derived from forest inventory data) appears to have played, at least in this approach and for some territories, a secondary role in explaining the registered fire regime patterns. 1. Introduction Forest fires are recurrent disturbances that can be characterized by their regime, that is, the type of fire history registered in a defined area for a given time period [1, 2]. A fire regime is determined by a large number of factors: the presence of ignition sources, topography, prevention, and extinction efficiency; existence of climatic conditions which favour the spread of fire; the amount, type, and arrangement of fuels at several spatial scales [3, 4]. A fire regime can be characterized by means of a large variety of variables describing different aspects of fire incidence (e.g., [5, 6]). Here I use the fire frequency and three variations of the fire rotation period using a 32?yr. time period. In recent decades there has been a high incidence of forest fires in peninsular Spain, which have affected a large number of forest ecosystems and severely disturbed the dynamics and structure of the vegetation [7]. In addition, Mediterranean type ecosystems are among the most vulnerable to climatic change and will suffer severe consequences [8–10]. This is partially due to the expected increase in the recurrence of severe drought and to the warmer and more arid conditions anticipated as a result of higher
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