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Incendios forestales en Espa??a. Ecosistemas terrestres y suelos
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... This new scenario has been attributed to global change drivers, such as rural land abandonment and climate change [11,[20][21][22]. Also, forestry policies based on reforestation, mainly of flammable pine trees, have promoted landscapes dominated by pyrophytic vegetation prone to extreme fire behavior [23]. ...
Vegetation structural complexity (VSC) plays an essential role in the functioning and the stability of fire-prone Mediterranean ecosystems. However, we currently lack knowledge about the effects of increasing fire severity on the VSC spatial variability, as modulated by the plant community type in complex post-fire landscapes. Accordingly, this study explored, for the first time, the effect of fire severity on the VSC of different Mediterranean plant communities one year after fire by leveraging field inventory and Sentinel-1 C-band synthetic aperture radar (SAR) data. The field-evaluated VSC retrieved in post-fire scenarios from Sentinel-1 γ⁰ VV and VH backscatter data featured high fit (R² = 0.878) and low predictive error (RMSE = 0.112). Wall-to-wall VSC estimates showed that plant community types strongly modulated the VSC response to increasing fire severity, with this response strongly linked to the regenerative strategies of the dominant species in the community. Moderate and high fire severities had a strong impact, one year after fire, on the VSC of broom shrublands and Scots pine forests, dominated by facultative and obligate seeder species, respectively. In contrast, the fire-induced impacts on VSC were not significantly different between low and moderate fire-severity scenarios in communities dominated by resprouter species, i.e., heathlands and Pyrenean oak forests.
... Erosion is primarily determined by the severity of the burn, as well as the changes in soil properties such as SOM, bulk density, and hydraulic characteristics (e.g., Ebel et al.,2012)). The negative effects of fires on soil properties are well known throughout the world (Mataix-Solera and Cerdà, 2009) and depending on fire fueling and initial soil moisture, changing macro-and micro-nutrients, color, pH, bulk density, and soil biota (Datta, 2021;Verma and Jayakumar, 2012). Fire alters the composition of the microbial community by affecting the structure of the microbiota and microfauna (Köster et al., 2021). ...
As wildfires have increased and become more frequent in recent years, researchers area focusing on how wildfires affect ecosystem resilience, which has serious implications for the recovery and protection of native forests and plantations. Most physicochemical and biological soil properties, including soil surface mineralogical composition, can be severely impacted by fires. However, no attempt has been made from a bibliometric point of view to provide a comprehensive picture of the research status on fire effects in mineralogy and nutrient stocks. Using the VOSviewer software, this study aims to evaluate fire effects on mineralogy and nutrients (FMN), the thematic evolution and determine the most relevant trends based on the intellectual structure of the knowledge built up in this research field. The methodology is divided into two stages: (i) Data Collection, and (ii) Bibliometric Analysis and Data Mining (Performance Analysis and Science Mapping). A detailed bibliometric analysis was performed on 530 Web of Science (WOS) articles indexes from1984 to 2020. Overall, the results show that Forest Ecology and Management is the leading journal in the field. The top three countries hosting core research centers for this topic are the United States, Spain, and France. Certini G. was the author with more citations (1395) in one paper and Johnson, D. had the most published papers (19) with a total of 549 citations. Currently, the hotspots of fire issues mainly include soil nutrients (e.g. nitrogen, phosphorus, carbon, and calcium); in addition to the selected keywords, wildfires co-occur more frequently with disturbances and terms such as soils, water quality, boreal forests, and stream. In conclusion, 530 articles written by 1822 authors and their research displayed in 211 journals from universities and research centers in 60 countries demonstrate the growing interest in the field.
... In the Mediterranean environment, forest fires can be a significant disturbing factor influencing, especially if recurrent, forest ecosystem functioning (Attiwill 1994;Van Lierop and Lindquist 2015;FAO 2016). Recently, the number of fires have increased in most Mediterranean regions (JRC 2018), with significant impact not only on forests but also on chemical, physical and biological soil properties (Certini 2005;Mataix-Solera and Cerdà 2009;Š imanský et al. 2012). The way fire affects soils and how intense its impact is on an ecosystem, depend primarily on how the fire burns. ...
Considering that diverse fire severities can affect soil properties differently, the aim of this study was to examine to what extent changes in soil properties caused by fire could condition seedling establishment. This new approach is for identifying a new fire cause-effect chain to qualify the impacts of fire on soils with the purpose of using fire as a tool in forest management to favour Pinus halepensis Mill. regeneration. The study area was a reforested P. halepensis area which had been crossed by fire for 78.8 ha, causing various degrees of damage. The forest was subdivided into three large areas according to the gravity of crown scorch, [low (LS), medium (MS) and high (HS) severity], on the basis of needle yellowing which usually occurs after exposure to direct flames. Results showed significant differences in soil properties with respect to fire severity. In the HS area, total nitrogen and carbon were considerably reduced while ash and phosphorus contents significantly increased. The changes in soil properties, in particular to nutrient levels, affected P. halepensis regeneration, mainly the first year after the fire. Greater regeneration occurred in areas affected by moderate fire severity in which the temperatures reached increased the mineralization of soil organic matter with the consequent release of nutrients available for seedling growth. Additionally, moderate fire severity suppressed the regeneration of grasses, reducing the interspecific competition. Heights of seedlings were inversely proportional to the density of grasses. Where the number was abundant (LS), the height was modest; conversely, where the number was low (HS), the greater hypsometric differentiation of pine seedlings was observed. These results suggest that moderate fire severity represents an environmental stress (hormesis) altering microscale conditions to increase pine germination and establishment. The exposure of P. halpensis to a moderate environmental factor that is damaging at higher intensities, induces an adaptive beneficial effect on seedling regeneration. This data can re-evaluate the assertion that coniferous burned areas, if left unmanaged, would remain unproductive for an indefinite period.
Wildfire activity has decreased in the Valencia Region (Eastern Spain) in the last three decades in ignition and spread terms despite adverse climatological conditions caused by climate change, measured by the Fire Weather Index (FWI) in this study. We divided the study area into seven homogenous regions and split fires by cause to disaggregate the results, and to check for trends in these variables. The most relevant results were: 1) wildfire activity, especially in ignition terms, is decoupled from meteorological danger; 2) annual and interannual FWI variation fits changes in wildfire activity, although the decreasing fires trend masks any significant correlation; 3) summer is the most dangerous season, although large fires and adverse climatological conditions may occur in other seasons; 4) the majority of fires are manmade, with natural fires predominating in the northwest; 5) wildfires undergo significant regional differences that fit the type and intensity of the land use that predominates in each region; 6) the FWI is a good indicator of fire danger, and higher FWI values result in large and abundant fires; 7) responsible action and awareness have resulted in less wildfire activity in recent decades. While the increase in funds and equipment to prevent and combat fires has reduced their impact, ever more adverse conditions in the future caused by climate change will require making more effort to deal with wildfires by placing the focus beyond the warmest summer months.
Publicación que compila trabajos completos presentados en las VII Jornadas Interdisciplinarias "Ciclo del Agua en Agroecosistemas". Centro de Estudios Transdisciplinarios del Agua. Facultad de Ciencias Veterinarias, Universidad de Buenos Aires. Argentina.
En las últimas décadas, el cambio en el modelo de producción agrícola y el desarrollo de filosofías animalistas han puesto las antiguas prácticas rurales en el punto de mira de las críticas sociales. Además de la agricultura y la ganadería, otras actividades condenadas son la caza y la recolección, especialmente la primera. Las mismas, en base a la investigación realizada mediante recursos bibliográficos y trabajo de campo, se consolidan como prácticas de gran potencial para la producción sostenible futura. Como respuesta se ofrece un posicionamiento filosófico-científico, que sienta las bases para la creación de un proyecto artístico que tiene como objetivo principal reivindicar la caza y la recolección sostenibles. El resultado que se presenta es un proyecto de álbum ilustrado infantil —pero dirigido a todos los públicos— a través de su proceso creativo: desarrollo del guion, planificación mediante storyboard, el diseño de los personajes y algunas de sus ilustraciones definitivas. Las imágenes muestran el potencial de la caza y la recolección en una producción sostenible futura, así como la idoneidad de la obra artística como defensa de la preservación de la cultura y la naturaleza, sin renunciar al avance y desarrollo de la sociedad.
Severe wildfires cause important changes in vegetation and soil properties in Mediterranean ecosystems. The aim of this work was to evaluate ecosystem multifunctionality through the study of burn severity short-term effects on different ecosystem functions and services. We selected the Cabrera wildfire (2017) in northwest Spain. Burn severity was quantified using CBI index, differentiating four categories: unburned, low, moderate, and high severity. We established a total of 126 field plots, where one year after fire the vegetation was evaluated and soil samples for the analysis of chemical, biochemical, and microbiological properties were collected. Sentinel-2 images were used to obtain vegetation biophysical variables. Vegetation and soil variables were directly applied as indicators, or used to calculate other indicators, which were standardized and selected to define ecosystem functions and services: (1) photosynthetic activity, soil fertility, nutrient cycling, and soil quality (supporting ecosystem service); (2) grass production for livestock and wood production (provisioning ecosystem service); (3) climate regulation and erosion protection (regulating ecosystem services), and (4) woody species diversity and aesthetic value (cultural ecosystem services). The combination of these functions and services defined ecosystem multifunctionality. The main results showed that burn severity negatively affected most ecosystem functions, as well as the ecosystem services of supporting, provisioning, and regulating, and hence, ecosystem multifunctionality. However, the soil fertility function significantly increased with high burn severity, while woody species diversity and aesthetic value functions and, consequently, the cultural ecosystem service, only decreased under the effect of moderate severity. These results provide a starting point to study burn severity effects from a multifunctional approach in Mediterranean ecosystems.
Recent changes in fire regimes, with more frequent, extensive, and severe fires, are modifying soil characteristics. The aim of this study was to evaluate the effect of burn severity on the resistance of some physical, chemical, and biochemical soil properties in three different forest ecosystems affected by a wildfire in the northwest of the Iberian Peninsula. We evaluated burn severity immediately after fire using the Composite Burn Index (CBI) in three different ecosystems: shrublands, heathlands, and oak forests. In the same field plots used to quantify CBI, we took a composite soil sample to analyse physical (mean weight diameter (MWD)), chemical (pH; total C; total organic C (TOC); total inorganic C (TIC); total N; available P; exchangeable cations Na⁺, K⁺, Mg²⁺, and Ca²⁺; and cation exchange capacity (CEC)), and biochemical (β-glucosidase, urease, and acid phosphatase enzyme activities) properties. The resistance index of each property was then calculated. Based on our results, the values of the soil chemical properties tended to increase immediately after fire. Among them, total C, TOC, and exchangeable Na⁺ showed higher resistance to change, with less variation concerning pre-fire status. The resistance of chemical properties was higher in the oak forest ecosystem. MWD decreased at high severity in all ecosystems, but soils in shrublands were more resistant. We found a high decrease in soil enzymatic activity with burn severity, with biochemical properties being the least resistant to change. Therefore, the enzymatic activity of soil could be a potential indicator of severity in forest ecosystems recently affected by wildfires.
The greatest threat to biodiversity is the alteration and destruction of habitats, and one of the causes is tree plantation, which normally are monospecific and unnatural high-density forest stands. In Spain these contain mainly Pinus species, and cover 25% of the forested area. Due to their dense canopy cover, these monocultures harbor poor communities in terms of species richness and abundance of other organisms, such as reptiles. In November 2014, wind storms affected a pine plantation in the western end of the Sierra Nevada Natural Park, totally or partially knocking down pines 65 years old. We have studied the response of the reptile community in the affected plots three and five years after the disturbance. Due to the low thermal quality of pine plantations for reptiles, we hypothesized that reptile community metrics (abundance and species richness) would be positively affected by this perturbation. We found greater richness and density of reptiles in the plots affected by maximum and intermediate disturbance than in the non-affected plots. We conclude that natural catastrophic events such as wind storms can diversify reptile communities in Mediterranean pine plantations thanks to a rapid response of generalist reptile species.
ABSTRACT To determine the effects of different burning intervals on soil N status insubstands of sapling-, pole-, and sawtimber-sized ponderosa pine (Pinus ponderosa Laws.) we sampled plots burned at 1-, 2-, and 4-yr intervals by three strata at two depths (0-5 and 5-15 cm). Generally, NH4+; and NO3- concentrations were higher on plots repeatedly burned than on unburned controls. However, plots not reburned for 4 to 5 yr had concentrations similar to controls. No significant difference in total (organically bound) N was found among treatments. We conclude that frequent periodic burning can be used ,to enhance ,N availability in southwestern ponderosa pine sites. Additional Index Words: fire effects, NH4+, NO3- , Pinus ponderosa
Fire may generate soil degradation and accelerate erosion processes, depending among other factors, on the regeneration capacity of the ecosystem. Conservation measures will be beneficial in those fragile systems where a high degradation hazard is estimated. Mulching treatment was evaluated in order to establish its efficiency in protecting soil and preventing runoff generation in a semiarid area affected by a wildfire. Straw mulch was applied at 200 g m in three replicated plots. Paired mulched and control plots were established in a three block experimental design. Runoff, sediment yield, plant cover, and dynamics of soil physical properties were measured in these plots over a 2‐year period. Most of the plant regeneration after the fire resulted from resprouting of the dry grassland species, dominated by Brachypodium retusum. Total plant cover was only 50% two years after passage of the fire. Runoff and sediment yield were significantly greater from control plots. Soil loss from control plots was about 7.2 times higher than the loss from mulched plots. Surface runoff showed similar differences. Mulching also reduced surface crusting and slightly stimulated vegetation growth.
Ecologists, biogeographers, and paleobotanists have long thought that climate and soils controlled the distribution of ecosystems, with the role of fire getting only limited appreciation. Here we review evidence from different disciplines demonstrating that wildfire appeared concomitant with the origin of terrestrial plants and played an important role throughout the history of life. The importance of fire has waxed and waned in association with changes in climate and paleoatmospheric conditions. Well before the emergence of humans on Earth, fire played a key role in the origins of plant adaptations as well as in the distribution of ecosystems. Humans initiated a new stage in ecosystem fire, using it to make the Earth more suited to their lifestyle. However, as human populations have expanded their use of fire, their actions have come to dominate some ecosystems and change natural processes in ways that threaten the sustainability of some landscapes.
This paper evaluates the changes in the erosional and hydrological processes after a forest fire under Mediterranean climatic conditions by means of simulated rainfall experiments. The measurements taken in different seasons demonstrate that immediately after the fire (in summer) the surface runoff and the erosion rates were negligible due to the high infiltration rates of the dry and ash covered soils. The winter following the fire (4 months later) surface runoff and erosion rates were very high (57.3%, 148 g m2h-1) due to the high moisture content, crusting and the low vegetation cover. The following measurements show a rapid decrease in the surface runoff, sediment concentration and erosion rates. The runoff coefficients were always higher in the wet season (winter) than in the dry season (summer) as a consequence of the contrasting seasonal soil water regime in mediterranean conditions and were similar to the rates found in scrubland areas not recently affected by fire. Three, four and five years later the measurements show very low runoff and erosion rates. Pre-fire runoff rates were reached earlier for summer conditions (2 years) than for winter conditions (>4 years). The natural erosion rates were reached one year after the first for summer conditions and 18 month later for the winter conditions. Spatial variability of runoff and erosion was very low immediately after the fire and very high four months later under winter conditions, decreasing gradually with the recovery of the pre-fire conditions: growth of vegetation, low runoff and negligible erosion rates.
Hillslopes are thought to be most susceptible to enhanced surface runoff and erosion immediately following wildfire due to removal of protective vegetation and litter cover, and in many cases a fire-induced reduction in soil wettability. This enhanced susceptibility declines as vegetation and litter layer recover. For logistical reasons, however, few studies have been able to examine the responses of burnt terrain immediately following burning and little is therefore known about the effect of the wettable ash layer that often covers the ground until it is redistributed or removed by wind or water erosion.
In order to evaluate the soil loss in a burnt forest and the role played by slope orientation in erosion, a study has been carried out in the Montserrat area (NE Spain) affected by a fire in summer 1986. Previous geomorphological surveys allowed us to propose the hypothesis that slope orientation acted as a macrofactor or integrating factor in erosion control. Aspect controls temperature, moisture and water supply and then vegetation and soil development.The evaluation was determined by monitoring two experimental plots 250 m apart developed on equal substrate and slope but one facing north and the other facing south. The plots, with a surface area of 200 m2 are equipped with collecting and sampling units (Multi-slot divisors) and storage tanks.The results (August 1987 – December 1988) confirm the contrast in runoff and soil losses according to slope orientation (2176 g/m2 south-facing plot and 352 g/m2 north-facing plot). This different erosive response is mainly due to:a)the state of the vegetation and soil development before the fire,b)the differences in vegetation recovery after fire.The north-facing slopes had a denser plant cover and thicker soil than the south-facing ones. After the fire the north-facing slopes were covered by a thicker blanket of ashes and burnt plant debris and, later, more vegetation giving the soil higher infiltration capacity and resistance.Moreover, the two major events displayed different behaviour according to slope orientation. The first of those events, due to the conditions on each slope (higher or lower protection and available erodible material) gave rise to a change in the threshold conditions:a)the rill formation on the south-facing plot enhanced the flow concentration and sediment transport (lowering of threshold) in the second event andb)on the north-facing one, the lack of rills and the decrease in erodible material caused by the first event hindered subsequent erosion (threshold rise).Finally, the progressive recovery of spontaneous vegetation caused erosion to drop, reaching low rates in 1988 (22 g/m2 and 2 g/m2 on each plot).
This paper reports the influence that vegetation recovery has exerted on the soil behaviour to erosion by water during both the first and eight years after experimental fires. The work was carried out at La Concordia Experimental Station (Valencia, Spain), which includes nine plots (4 m wide×20 m long) installed on a calcareous hillside representative of Mediterranean shrubland areas. In June 1995 a set of experimental fires were carry out at two intensity levels (high and moderate) with three plots replication for each treatment. The remaining three plots were used as the control. Rain events between June 1995 to June 1996 and from June 2002 to June 2003 were monitored and their effect on soil erosion processes determined. The vegetation changes (biomass amount and plant cover) for each studied period were also assessed.Total runoff and sediment yield measured during the first post-fire year was 19.43 L m−2 and 561 g m−2 in the intense fire, and 14.72 L m−2 and 326 g m−2 in the moderate one, which contrasts with the very low runoff (3.82 L m−2) and soil loss (8.56 g m−2) in control plots. Eight years after the fire, the amount of vegetation on the burned plots represents between 63 and 69% compared to the biomass present before the fire in 1995. The regeneration of plant cover, up to 30–40% eight years after the fire, facilitated a decrease in the difference of soil losses between fire treatments and between burned and unburned plots. However, runoff generation still remains greater in burned plots than in the control ones eight years after the fire.