SHORT-TERM EXPERIMENTAL FIRE EFFECTS IN SOIL AND WATER LOSSES IN SOUTHERN OF SPAIN Juan Francisco Martínez-Murillo 1 *, Paloma Hueso-González 1 , Jose Damián Ruiz-Sinoga 1 , Hanoch Lavee 2 1 Department of Geography, University of Málaga, Andalucía Tech. Campus de Teatinos, 29071 Málaga, Spain 2 Department of Geography and the Environment, Bar Ilan University, Ramat-Gan 5290002, Israel Received: 10 February 2015; Revised: 20 January 2016; Accepted: 20 January 2016 ABSTRACT This study deals with the experimental fire effects in overland flow and soil erosion at plot scale and considering rainfall erosivity. The study was conducted in from May 2011 to Dec 2013. Six plots of 12-m length and 2-m width are considered: four of them were burned, whilst two of them remained in natural conditions. Overland flow was collected in deposits of 250 L after each rainfall event, measured at a meteorological station. Larger rainfall intensities and erosivity were registered after summer and, thus, overland flow and sediment yield, but one order of magnitude higher in the burned plots than in the unburned ones. Especially, the difference in overland flow and soil loss between both set of plots were nearly three folds larger whether the rainfall intensity exceeded 30 mm h 1 during 15-min intensity. It is remarkable that the most erosive event generating the maximum values of overland flow and soil loss was registered 16 months after the experimental fire when a rainfall event of 99·2 mm h 1 occurred. This delay is considered as consequence of soil surface conditions and ash cover. Copyright © 2016 John Wiley & Sons, Ltd. key words: experimental fire; rainfall erosivity; overland flow; soil loss; plot INTRODUCTION Soil erosion is one of the most significant environmental problems worldwide (Bakker et al., 2007). This is particu- larly true in areas having seasonally contrasted climate and a long history of human pressure, such as the Mediterranean areas that are characterized by decreasing forested areas due to the expansion of livestock rearing in the past, recurrent fires, the cultivation of steep slopes and expansion of urban- ization process (López-Bermúdez, 2008; García-Ruiz et al., 2013; Zdruli, 2014; Ferreira et al., 2015). Soil loss was commonly predicted using empirical models such as the Universal Soil Loss Equation (USLE) (Wischmeier & Smith, 1965) and its revisions (RUSLE). Among the empirical coefficients used to calculate potential erosion, rainfall erosivity represents a natural environmental constraint on soil erosion that limits and conditions land use and man- agement (Angulo-Martínez & Beguería, 2009). The concept of rainfall erosivity presented by Hudson (1971) and Wischmeier and Smith (1978) describes the erosivity as an interaction between kinetic energy of raindrops and the soil surface. Its calculation is dependent on maximum rainfall intensity values. This can result in a greater or lower degree of detachment and downslope transport of soil particles according to the amount of energy and intensity of rain by considering the same soil type, the same topographic condi- tions, soil cover and management (da Silva, 2004). Indeed, the rainfall erosivity not only controls the soil erosion but also the plant establishment (Wang et al., 2014). In a Mediterranean environment, wildfire is commonly regarded as one of the major agents of soil erosion and land degradation (DeBano et al., 2005; Cerdà & Mataix-Solera, 2009). Wildfires have a long history in the Mediterranean since late Quaternary (Carrión et al., 2003) and even longer as fire adaptations of many endemic plant species indicate (Pausas et al., 2008). Major concern about wildfires and their effects in the region began in the 1960s, 1970s and 1980s (Shakesby, 2011) as a consequence of an exponential increase in fire activ- ity (Moreno et al., 1998; Pausas, 2004). This increment is commonly due to a decreasing of total rainfall and an increas- ing of temperature over recent decades (Stott et al., 2004; Harding et al., 2009). However, human influences, including land use change brought about by widespread socio-economic change and urban expansion, have been viewed as the main drivers of the dramatic increase in wildfire activity (Pausas et al., 2008; Shakesby, 2011; Bodí et al., 2012; Carreiras et al., 2014; Pereira et al., 2015). One of the ways in reducing wildfire hazard is prescribed fires to reduce fuel in forests and rangelands, but the little-known effects of such prescribed burnings on entire ecosystems induced debate and research activities in various disciplines. In Mediterranean areas, overland flow and thus sediment yield are controlled by factors such as rainfall regime, topog- raphy, land use and vegetation cover as well as soil proper- ties. The vegetation cover protected the soil from being eroded due to decreasing the probability of overland flow generation. However, the impact of wildfires on vegetation cover and chemical, physical, biological and mineralogical *Correspondence to: J. F. Martínez-Murillo, Department of Geography, University of Málaga, Andalucía Tech. Campus de Teatinos, 29071 Málaga, Spain. E-mail: jfmmurillo@uma.es Copyright © 2016 John Wiley & Sons, Ltd. land degradation & development Land Degrad. Develop. (2016) Published online in Wiley Online Library (wileyonlinelibrary.com) DOI: 10.1002/ldr.2504