Agricultural and Forest Meteorology 116 (2003) 49–59 Modeling moisture content in shrubs to predict fire risk in Catalonia (Spain) F.X. Castro a,∗ , A. Tudela a , M.T. Sebastià b,c a Direcció General de Protecció de Riscos del Medi Natural, Departament de Medi Ambient, Generalitat de Catalunya, Finca Torreferrussa, Apartat de Correus 119, 08130 Santa Perpètua de Mogoda, Spain b Àrea d’Ecologia Vegetal i Botànica Forestal, Centre Tecnològic Forestal de Catalunya, Pujada del Seminari s/n, 25280 Solsona, Spain c Dept. Hortofructicultura, Botànica i Jardineria. Escola Tècnica Superior d’Enginyeria Agrària, Universitat de Lleida, Av. Rovira Roure 191, 25198 Lleida, Spain Received 3 July 2001; received in revised form 18 November 2002; accepted 3 December 2002 Abstract We measured the moisture content in small branches and leaves of Cistus monspeliensis in four Mediterranean locations of Catalonia (Spain), from 1998 to 2000. The moisture of the measured fraction is also known as live fine fuel moisture, and it provides the most significant fuel in wild fires in this region. The aim of the study was to model the live fine fuel moisture based on meteorological variables from automatic weather stations close-by, and several components of the Canadian index of forest fire danger. We wanted to generalize the estimates of live fine fuel moisture from this species to other localities throughout the region from the data obtained by the network of automatic weather stations. We developed two models. The second model, independent of the actual sampling date, was more general, but the addition of the temporal component improved the predictive ability of the first model. We validated the models with data collected at two locations in 2001 and 2002. The resulting adjustments reached R 2 of around 80%, for the predicted against the observed values for the test period. Therefore, the methodology developed provides a reliable tool to predict forest fire risk throughout the year. © 2002 Elsevier Science B.V. All rights reserved. Keywords: Forest fire; Live fine fuel moisture; Drought index; Cistus monspeliensis 1. Introduction The moisture content of small branches and leaves of shrubs (referred to as live fine fuel moisture, M) growing in fire prone regions determines the in- flammability of the vegetation and therefore the po- tential for the outbreak and spread of wild fires. The lower the moisture content of the vegetation, the more difficult it is to prevent the advance of fire. Live fine fuel moisture in plants is conditioned by parameters ∗ Corresponding author. E-mail address: francesc1962@mixmail.com (F.X. Castro). related to environmental factors, and to the life his- tory and ecophysiology of the particular plant species. Plants develop both morphological and physiological mechanisms in order to regulate their water content, and these adaptations are particularly apparent in plants from geographical areas regularly experiencing drought periods, such as the Mediterranean region. Live fine fuel moisture integrates variables related to species characteristics, climate, topography, and soils. Several authors have related live fine fuel moisture to flammability in Mediterranean species (Elvira and Hernando, 1989; Valette, 1993; Moro and Le Corre, 1993; Rochas, 1994), and have considered it to be an 0168-1923/02/$ – see front matter © 2002 Elsevier Science B.V. All rights reserved. doi:10.1016/S0168-1923(02)00248-4