Assessment of the vegetation cover in a burned area 22-years ago using remote sensing techniques and GIS analysis (Sierra de las Nieves, South of Spain).

The study aim was to characterize the vegetation cover in a burned area 22-years ago considering the previous situation to wildfire in 1991 and the current one in 2013. The objectives were to: (i) compare the current and previous vegetation cover to widlfire; (ii) evaluate whether the current vegetation has recovered the previous cover to wildfire; and (iii) determine the spatial variability of vegetation recovery after 22-years since the wildfire. The study area is located in Sierra de las Nieves, South of Spain. It corresponds to an area affected by a wildfire in August 8th, 1991. The burned area was equal to 8156 ha. The burn severity was spatially very high. The main geographic features of the burned area are: mountainous topography (altitudes ranging from 250 m to 1500 m; slope gradient >25Remote sensing techniques and GIS analysis has been applied to achieve the objectives. Landsat 5 and Landsat 8 images were used: July 13th, 1991 and July 1st, 2013, for the previous wildfire situation and 22-years after, respectively. The 1990 CORINE land cover was also considered to map 1991 land uses prior the wildfire. Likewise, the Andalucía Regional Government wildfire historic records were used to select the burned area and its geographical limit. 1991 and 2013 land cover map were obtained by means of object-oriented classifications. Also, NDVI and PVI1 vegetation indexes were calculated and mapped for both years. Finally, some images transformations and kernel density images were applied to determine the most recovered areas and to map the spatial concentration of bare soil and pine cover areas in 1991 and 2013, respectively. According to the results, the combination of remote sensing and GIS analysis let map the most recovered areas affected by the wildfire in 1991. The vegetation indexes indicated that the vegetation cover in 2013 was still lower than that mapped just before the 1991 widlfire in most of the burned area after 22-years. This result was also confirmed by other techniques applied. Finally, the kernel density surface let identify and locate the most recovered areas of pine cover as well as those areas that still remain totally or partially uncovered (bare soil.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Available water modifications by topsoil treatments under mediterranean semiarid conditions: afforestation plan

During dry periods in the Mediterranean area, the lack of water entering the soil matrix reduces organic contribu- tions to the soil. These processes lead to reduced soil fertility and soil vegetation recovery which creates a positive feedback process that can lead to desertification. Restoration of native vegetation is the most effective way to regenerate soil health, and control runoff and sediment yield. In Mediterranean areas, after a forestry proposal, it is highly common to register a significant number of losses for the saplings that have been introduced due to the lack of rainfall. When no vegetation is established, organic amendments can be used to rapidly protect the soil surface against the erosive forces of rain and runoff. In this study we investigated the hydrological effects of five soil treatments in relation to the temporal vari- ability of the available water for plants. Five amendments were applied in an experimental set of plots: straw mulching; mulch with chipped branches of Aleppo Pine (Pinus halepensis L.); TerraCotten hydroabsobent polymers; sewage sludge; sheep manure and control. Plots were afforested following the same spatial pattern, and amendments were mixed with the soil at the rate 10 Mg ha-1. In control plots, during June, July, August and September, soils were registered below the wilting point, and therefore, in the area of water unusable by plants. These months were coinciding with the summer mediter- ranean drought. This fact justifies the high mortality found on plants after the seeding plan. Similarly, soils have never exceeded the field capacity value measured for control plots. Conversely, in the straw and pinus mulch, soils were above the wilting point during a longer time than in control plots. Thus, the soil moisture only has stayed below the 4.2 pF suction in July, July and August. Regarding the amount of water available was also higher, especially in the months of December, January and February. However, the field capacity value measured has not showed any differences regarding the control. For these treatments, the survival sapling rates measured were the highest. Sludge, manure and polymers showed a moisture retention capacity slightly more limited than straw and pinus mulch. Likewise, it has been found that the area of usable water by plants was also lower, especially during the months of January and February. This situation is especially sharpened in plots amended with manure. In this treatment, the upper part of the soil profile was below the wilting point for six months a year (from April to August). For this treatment, the survival sapling rates measured were the lowest. In conclusion, from a land management standpoint, the pinus and straw mulch treatments have been shown as effective methods reducing water stress for plants. In this research, mulching has been proved as a significant method to reduce the mortality sapling rates during the mediterranean summer drought.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Impact of prescribed fire in soil properties after 5-years: experimental study.

Wildfires are a serious problem in areas with a Mediterranean climate owing to the hot summers and drought conditions providing perfect conditions for wildfire, especially when there are large amounts of fuel accumulation and continuity between forested areas. In the Mediterranean, high severity fires that spread rapidly are common and difficult to be extinguished. Thus, the identification of tools to reduce fire spread and minimize their incidence and effects is crucial. Preventive forestry is a good tool for achieving forest structures with lower amounts of fuel and a greater resistance to fire. Prescribed fire is the planned use of fire under predetermined weather, fuel and topographic parameters to achieve clearly defined objectives as controlling fire regimes by managing fuel, counteracting the disappearance of biomass-consuming land management practices and reducing the overall fire risk. Normally, prescribed fires are low intensity fires and, if managed adequately, do not cause any damage to trees, especially in Mediterranean ecosystems where trees are resilient to fire. Besides, prescribed fires usually have different impacts on soils, water resources, biodiversity, the risk-reduction of wildfires and carbon storage. Prescribed fires usually are of low/moderate severity. Because of this, the effects of prescribed fires on soils properties may vary from one site to another. The objectives of our study are to: i) determine the impact of the prescribed fire just after and ii) 5-years later with respect to natural conditions. To do this, in 2011, a prescribed fire was conducted in one experimental area of Mediterranean rangeland. After the fire, soil samples (0-5 cm of depth) were taken in burned and unburned plots in order to analyse: pH, electrical conductivity (EC), soil organic carbon, cationic exchangeable capacity (CEC), aggregate stability (AS), and hydrophobicity. The results indicated that: i) prescribed fire only had significantly effects in CEC just after the fire; 5-years after, there were no significant differences between the unburned and burned plots, but two soil properties significantly changed when burned soil samples from 2016 and 2011 were compared: EC and AS in the fraction of 0.053-0.125 mm. In general, the soil properties were not substantially modified by the prescribed fire, supporting the idea it is a very useful tool with very low impact for managing Mediterranean rangelands in order to reduce fuel accumulation and fire risk.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Hydrological and sediment connectivity in three grazed Mediterranean hillslopes.

Masselink et al. (2016) addressed the concept of connectivity addresses the spatial and temporal variability in runoff, sediment transport and associated substances such as pollutants and how these move through the catchment. Sediment connectivity explains which sediment sources contribute and where (semi-) permanent sinks and pathways of sediment are (Bracken & Croke, 2007). The Mediterranean eco-geomorphological landscape is highly dependent on the climatic conditions. Its elements form the spatial patterns of landscapes, which control the structural connectivity. The existence of rainfall gradients in the Mediterranean region has been well-documented (Lavee et al., 1998) along which those elements are modified by the spatio-temporal variability of rainfalls. The characteristics of those elements are modified from the rainiest to the driest regions following a positive feedback process leading to soil erosion and degradation. As the climate becomes less rainy, the patchy vegetation pattern becomes frequent and bare soil areas can be easily connected whether the magnitude and intensity of rainfall exceed a certain threshold (Cammeraat, 2004). The interaction between topography and processes occurring within catchments is key to understanding dynamics of hydrological connectivity (Wainwright et al, 2011). Our study evaluated the hydrological and sediment connectivity between sections (top, middle and bottomchannel) from three grazed hillslopes located under contrasted Mediterranean climatic conditions. Rain-gauge stations and opened-plots were installed in order to register overland flow and sediment concentration from Feb-2008 to Jan-2010. The results indicated that: i) major volumes of overland flow and sediment transport occurred more frequently in humid and semiarid sites; ii) the more frequent hydrological connectivity was observed between the middle and bottom-channel sections, though the major values of overland flow and sediment concentration were registered in the upper sections; iii) it was found very frequent those rainfall events in which all sections contributed with overland flow and sediment to the channel; iv) the factors controlling hydrological and sediment connectivity varied from one site to another depending on the rainfall regime and vegetation cover, though the soil surface conditions were found a key factor in all of them. In summary, the grazing activity contribute to distance the hydrological and sediment connectivity processes from three hillslopes located under contrasted Mediterranean climatic conditions from the response expected for the three of them. References Bracken LJ, Croke J. 2007. The concept of hydrological connectivity and its contribution to understanding runoff-dominated geomorphic systems. Hydrological Processes 21: 1749–1763. Cammeraat ELH. 2004. Scale dependent thresholds in hydrological and erosion response of a semi-arid catchment in Southeast Spain. Agriculture, Ecosystems and Environment 104: 317–332. Lavee H, Imeson AC, Sarah P. 1998. The impact of climate change on geomorphology and desertification along a Mediterranean-arid transect. Land Degrad. Develop. 9: 407-422. Masselink RJH, Keesstra SD, Temme AJAM, Seeger M, Giménez R, Casalí J. 2016. Modelling discharge and sediment yield at catchment scale using connectivity components. Land Degrad. Develop. 27: 933-945. Wainwright J, Turnbull L, Ibrahim TG, Lexartza-Artza I, Thornton SF, Brazier R. 2011. Linking environmental regimes, space and time: interpretations of structural and functional connectivity. Geomorphology 126: 387–404.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

The geomorphological rainfall in the Mediterranean landscape modeling

The kinetic energy derived from the heavy rainfall constitutes one of the main factors of the geomorphological processes in Mediterranean environments, as well as in the landscape and the ecosystem modeling, resulting from its extraordinary spatial and temporal variability. When the rainfall is analyzed, particularly in Mediterranean climate and in the context of Climate Change, it is not only necessary to consider the total rainfall collected annually, but also it is essential to take into account other variables as intensity, duration, and frequency. A series of extreme rainfall databases have been analyzed for the last 25 years (1993-2017), with daily, horary and 10-minutes registers. These have been obtained from different weather stations belonging to the Agencia Estatal de Meteorología –AEMET- and the S.A.I.H. Hydrosur Network, spatially distributed in two regions of the province of Malaga. (Guadalhorce and Axarquía). The results show the limited frequency of the events considered as torrential rainfall according to the Agencia Estatal de Meteorología criteria ( 100mm/24h; 60mm/60’) and a high occurrence of shorts heavy downpours ( 10mm/10’), especially in recent years. These downpours have been classified as “geomorphological rainfall”, short events capable of activating hydro-soil processes, owing to its high intensity and the vulnerable conditions of the eco-geomorphological system in the study areas

Analysis of heavy rainfall in two contrasted Mediterranean watersheds from 1993 to 2017

"Despite the proximity of the watersheds there are strong" "environmental contrasts between both." "• The current rainfall dynamics follows a trend towards concentration in fewer days." "• A rainfall cataloged as torrential by the AEMET (≥ 100 / 24h, ≥60 mmh-1) is not necessary to activate erosion and degradation processes, especially when the system conditions are vulnerable. There are downpours hidden in the hourly precipitation data that get at very high intensities." "• It is considered the need to analyze exhaustively the characteristics of a given system, in order to establish what capacity of response has a specific area in an event of extreme precipitation.

Optimización de la estrategia de muestreo en campos abandonados mediante funciones variogramas.

Los campos abandonados en la montaña mediterránea suelen verse afectados por la degradación del suelo y la erosión hídrica. Su sistema ecogeomorfológico es de gran variabilidad espacio-temporal y su resiliencia depende del clima y de la degradación edáfica en el momento del abandono. Esta degradación depende de factores locales por lo que la variabilidad espacial del proceso es muy elevada. Las funciones variogramas permiten conocer dicha variabilidad y la correlación espacial entre las variables y mejorar la estrategia de muestreo según dichos factores locales.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech. Asociación de Geógrafos Españoles. Universitat Illes Balear

Variaciones estacionales en la generación de escorrentía y emisión de sedimentos en una ladera de los Montes de Málaga (provincia de Málaga)

En una ladera representativa de los Montes de Málaga, de antiguo manejo agrícola y actualmente cubierta por vegetación de matorral, se han medido las variaciones estacionales de la generación de escorrentía y la emisión de sedimentos en los distintos ambientes que conforman su sistema eco-geomorfológico. Ello fue llevado a cabo mediante dos técnicas: 1) simulaciones de lluvia realizadas en octubre de 2004 (inicio de la estación hidrodinámica activa) y marzo 2005 (mediados de la estación hidrodinámica activa), y 2) seguimiento de la afección de eventos de lluvia reales en parcelas cerradas de diferentes longitudes. Los resultados ofrecen unas variaciones estacionales considerables: i) predominio de las condiciones favorables para la generación de escorrentía en otoño, por la presencia de un suelo extremadamente seco tras el verano, mostrando síntomas de hidrofobia; y ii) predominio de la infiltración a mediados de la estación húmeda una vez que el suelo fue humedeciéndose a lo largo de ésta.The seasonal changes of the runoff generation and sediment emission have been measured at a slope from Montes de Málaga. This slope was cultivated until fifty years ago and it is occupied by shrub vegetation now. Measures were carried out in every one of the environments which composed the eco-geomorphological system of the slope. Two methodologies have been used for the purpose: 1) rainfall simulations during October 2004 (beginning of active hydrodynamic season) and March 2005 (middle of active hydrodynamic season), and 2) closedplots with different longitude. Results shows considerable seasonal changes: i) favourable conditions for runoff generation in Autumn a cause of a soil very dry after the summer showing hydrophoby, and ii) conditions for infiltration at the middle of the wet season once the soil was moistured along the active hydrodynamic season

Effects of fire and time in soil properties and geomorphological processes from peridotites relieves (South of Spain)

The province of Málaga is characterised by a great variety in geological and geomorphological processes affecting the Cordillera Bética relieves. One of the most impressive element is that of the peridotite relieves from which the most important one is Sierra Bermeja, though other peridotite rock outcrops can be found in other areas of the province. All together, the peridotite relieves constitute one of the largest ultramafic rock outcrop worldwide (>300 Km2). The peridotite is an igneous, hard and very dense rock composed by olivine and pyroxene. During the weathering the olivine is easily altered converting the peridotite into a clear blueish rock called serpentine accompanied by clay, and Fe and Mg oxide and hydroxide giving the typical red colour on surface. The soil developed over these relieves is called serpentine soil and characterised by exceptional limitations in nutrients (N, P, K, Ca, Mg) and high proportion of heavy metals (Cr, Ni, Co, Cu) influencing dramatically the type of vegetation covering the peridotite relieves. Historically, the peridotite relieves have been extremely deforested for grazing and wooded industry. Nowadays, all of them are covered by natural vegetation but in very different evolution stages: from very dense coniferous forest to shrubland covering soils scarcely. Apart from the deforestation, this is consequence of wildfires: in fact, the most extensive wildfires in the province of Málaga have mainly occurred over peridotite relieves. Because of this, their eco-geomorphological features in vegetation, soils and geomorphic processes, can be different from one site to another. The aim of this study is a preliminary characterization of the eco-geomorphological conditions from peridotites relieves affected by fire and, namely, evaluating the impact of fire and time in some soil properties and geomorphic features. To do this, several sites from peridotites relieves affected by fire since 1991 until 2017 were selected. In all of them, a field survey was conducted and consisted in the inventory of geomorphic processes associated to water erosion as well as the soil sampling at 0.5 cm of depth. In laboratory, the following soil properties were analysed: gravels, texture, organic matter content, pH, electrical conductivity, cationic exchangeable capacity, hydrophobicity, and aggregate stability. The results show the impact of fire and the eco-geomorphological evolution of the peridotites sites affected by wildfires in time. Nevertheless, more research are needed in order to achieve a better comprehension of the eco-geomorphology in this type of relieves impacted by wildfires considering the fire severity.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech