Elena Marcos

En las últimas décadas, la problemática relacionada con los incendios forestales se ha intensificado, especialmente en la cuenca Mediterránea, lo que genera una grave amenaza para los ecosistemas y las poblaciones humanas. Aunque han disminuido en número, los incendios son de mayor intensidad y severidad, superando la capacidad de extinción (incendios de sexta generación). Las causas de este aumento son diversas: factores socioeconómicos (despoblación, cambio de uso de suelo), gestión forestal deficiente, políticas inadecuadas y el cambio climático, agravados por la desinformación y sensacionalismo mediático. En este contexto socioambiental y de necesidad de información es necesario reforzar la capacidad de los nuevos especialistas en las actividades de prevención y restauración mediante diferentes estrategias. Por un lado, mediante mejoras en la gestión forestal, lo que conlleva la creación de masas forestales más resistentes a la propagación de los incendios forestales y con mayor capacidad de regeneración natural; por otro lado, actuando sobre las causas que originan la ignición, es decir, desarrollando concienciación social sobre las mismas. El proyecto Plantando Cara al Fuego (PCF) es una iniciativa que busca mejorar la concienciación ambiental y la participación ciudadana en la lucha frente a los incendios forestales, mediante su implicación en proyectos donde se aplican los conocimientos académicos a necesidades de la comunidad. Para ello, PCF desarrolla proyectos de innovación educativa basados en Aprendizaje-Servicio (ApS), metodología que integra la formación universitaria con la prevención y la restauración forestal. El objetivo de este trabajo es recopilar experiencias desarrolladas entre 2020 y 2025 en distintas comunidades autónomas españolas en las que el estudiantado universitario de titulaciones diversas ha desarrollado proyectos de ApS, contribuyendo a resolver problemáticas reales de sus comunidades ligadas a los incendios forestales mediante el diseño y desarrollo de actividades en colaboración con entidades públicas y privadas. Así pues, se analizan 35 proyectos, clasificados en 5 categorías (prevención, restauración, formación, multidisciplinar y divulgación), junto con indicadores de impacto educativo y social de la iniciativa: número de estudiantes implicados, empresas e instituciones colaboradoras, productos generados, TFGs o TFMs defendidos o alcance real de estos proyectos en términos poblacionales. Los resultados evidencian que el ApS fortalece la competencia profesional y el compromiso ambiental del alumnado, contribuyendo a la gestión sostenible del territorio.

Societal Impact Statement: Heathlands are globally important ecosystems that provide key functions and services but are increasingly threatened by land use changes. We investigated how plant diversity and productivity influence nitrogen cycling under different management regimes. Our findings reveal that extensive grazing modulates the relationship between plant diversity and soil nitrogen dynamics, with contrasting effects in grazed versus abandoned sites. Increased plant species diversity and abundance of annual and perennial herbs in grazed sites were associated with enhanced N mineralization rates. These insights highlight the need for adaptive management strategies to address the challenges posed by land use changes and biodiversity loss in heathland ecosystems. Summary: Abiotic controls on soil N‐transformations in heathlands are well understood; however, the effects of plant species diversity–productivity on N cycling remain unclear, particularly concerning grazing management. We evaluated the feedbacks among plant species diversity, functional group productivity and soil properties, as well as their relationship with net N mineralization rates, in six heathlands dominated by Calluna vulgaris with differing management history (grazed at low intensity and abandoned). Our findings revealed a pronounced increase in soil organic matter content with plant diversity in abandoned, species‐poor heathlands compared to the stronger feedback with soil total N in grazed, species‐rich sites, suggesting trade‐offs in the carbon‐to‐nitrogen ratio. Mean net ammonification, nitrification, and mineralization rates showed no significant differences between species‐rich and species‐poor heathlands. However, increased plant species diversity and abundance of productive functional groups in grazed sites were associated with enhanced N mineralization rates. In contrast, high species diversity in abandoned heathlands led to increased woody species productivity with traits related to nutrient conservation, which was linked to slower N mineralization rates. These findings enhance our understanding of the effects of the diversity‐productivity relationship on nitrogen cycling in heathlands, providing insights for anticipating ecosystem responses to changing management regimes.

Grasslands are one of the most abundant and biodiverse ecosystems in the world. However, in southern European countries, the abandonment of traditional management activities, such as extensive grazing, has caused many semi-natural grasslands to be invaded by shrubs. Therefore, there is a need to characterize semi-natural grasslands to determine their aboveground primary production and livestock-carrying capacity. Nevertheless, current methods lack a realistic identification of vegetation assemblages where grassland biophysical parameters can be accurately retrieved by the inversion of turbid-medium radiative transfer models (RTMs) in fine-grained landscapes. To this end, in this study we proposed a novel framework in which multiple endmember spectral mixture analysis (MESMA) was implemented to realistically identify grassland-dominated pixels from Sentinel-2 imagery in heterogeneous mountain landscapes. Then, the inversion of PROSAIL RTM (coupled PROSPECT and SAIL leaf and canopy models) was implemented separately for retrieving grassland biophysical parameters, including the leaf area index (LAI), fractional vegetation cover (FCOVER), and aboveground biomass (AGB), from grassland-dominated Sentinel-2 pixels while accounting for non-vegetated areas at the subpixel level. The study region was the southern slope of the Cantabrian Mountains (Spain), with a high spatial variability of fine-grained land covers. The MESMA grassland fraction image had a high accuracy based on validation results using centimetric resolution aerial orthophotographs (R² = 0.74, and RMSE = 0.18). The validation with field reference data from several mountain passes of the southern slope of the Cantabrian Mountains featured a high accuracy for LAI (R² = 0.74, and RMSE = 0.56 m²·m⁻²), FCOVER (R² = 0.78 and RMSE = 0.07), and AGB (R² = 0.67, and RMSE = 43.44 g·m⁻²). This study provides a reliable method to accurately identify and estimate grassland biophysical variables in highly diverse landscapes at a regional scale, with important implications for the management and conservation of threatened semi-natural grasslands. Future studies should investigate the PROSAIL inversion over the endmember signatures and subpixel fractions depicted by MESMA to adequately address the parametrization of the underlying background reflectance by using prior information and should also explore the scalability of this approach to other heterogeneous landscapes.

Fire has played a crucial role in shaping Earth's landscapes for millions of years and has been used as a cultural tool for human development for millennia. However, changing fire regimes driven by global change drivers and human influences are reshaping landscapes and leading to more severe wildfires, with significant socioeconomic and environmental consequences. These wildfires have substantial direct impacts on human lives, properties, and mental health, as well as indirect impacts on ecosystem services, negatively affecting provisioning, regulating, and cultural services. In general, severe wildfires disrupt the functioning of ecosystems and the subsequent recovery of the ecosystems services. Remote sensing techniques represent efficient tools for monitoring post-fire ecosystem service recovery. On the other hand, the impact of large fires is perceived differently by society influenced by socioeconomic factors, previous experiences, and community dynamics. Understanding these perceptions is essential for developing effective wildfire management and mitigation strategies at the local level. To address the challenges posed by changing fire regimes, a Fire Smart Territory (FST) approach could be considered, emphasizing integrated fire management that considers prevention, effective response, and post-fire restoration. This approach presented in this book chapter also promotes the involvement of local communities in fire prevention and management. So, the conservation of ecosystem services in fire-prone areas requires a holistic and adaptive approach that incorporates ecological knowledge, societal needs, and sustainable land management practices. By adopting an FST framework and considering the complex interactions between fire, ecosystems, and human communities, it is possible to mitigate the impacts of wildfires and promote resilience in these vulnerable landscapes.

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.

Fire activity has significant implications for ecological communities, biogeochemical cycles, climate, and human lives and assets

Terraces are a common Mediterranean feature influencing soils, slopes and subsurface hydrology; however, little is known about their impact on erosion processes, especially in humid regions. The purpose of this study was to assess how terracing after a fire affected erosion processes such as splash erosion. For 8 months, the study monitored splash erosion in three terraced plots, one plot under pre-fire conditions and the other two under post-fire conditions. Assessment of the impact of the terracing treatment in such plots was carried out by the installation of two different splash erosion quantitative systems: cups and funnels. An analysis of the splash data obtained in 17 rainfall events and meteorological data collected during each one of those periods was then performed. A significant positive correlation between the amount of rainfall and the splash erosion was observed. The two splash sampling systems show a high degree of concordance; however, the funnel-type model seems to be the most appropriate when it comes to preventing loss of splashed soil samples. The post-fire treatment with terracing leads to a smaller stability of surface soil aggregates, causing higher splash erosion rates. Sampling using the funnel system collects three times the amount of splashed soil than that collected by the cup system, although both systems correlate appropriately with the meteorological parameters.

Heterogeneous and patchy landscapes where vegetation and abiotic factors vary at small spatial scale (fine-grained landscapes) represent a challenge for habitat diversity mapping using remote sensing imagery. In this context, techniques of spectral mixture analysis may have an advantage over traditional methods of land cover classification because they allow to decompose the spectral signature of a mixed pixel into several endmembers and their respective abundances. In this work, we present the application of Multiple Endmember Spectral Mixture Analysis (MESMA) to quantify habitat diversity and assess the compositional turnover at different spatial scales in the fine-grained landscapes of the Cantabrian Mountains (northwestern Iberian Peninsula). A Landsat-8 OLI scene and high-resolution orthophotographs (25 cm) were used to build a region-specific spectral library of the main types of habitats in this region (arboreal vegetation; shrubby vegetation; herbaceous vegetation; rocks–soil and water bodies). We optimized the spectral library with the Iterative Endmember Selection (IES) method and we applied MESMA to unmix the Landsat scene into five fraction images representing the five defined habitats (root mean square error, RMSE ≤ 0.025 in 99.45% of the pixels). The fraction images were validated by linear regressions using 250 reference plots from the orthophotographs and then used to calculate habitat diversity at the pixel (α-diversity: 30 × 30 m), landscape (γ-diversity: 1 × 1 km) and regional (ε-diversity: 110 × 33 km) scales and the compositional turnover (β- and δ-diversity) according to Simpson’s diversity index. Richness and evenness were also computed. Results showed that fraction images were highly related to reference data (R² ≥ 0.73 and RMSE ≤ 0.18). In general, our findings indicated that habitat diversity was highly dependent on the spatial scale, with values for the Simpson index ranging from 0.20 ± 0.22 for α-diversity to 0.60 ± 0.09 for γ-diversity and 0.72 ± 0.11 for ε-diversity. Accordingly, we found β-diversity to be higher than δ-diversity. This work contributes to advance in the estimation of ecological diversity in complex landscapes, showing the potential of MESMA to quantify habitat diversity in a comprehensive way using Landsat imagery.

In Mediterranean fire-prone ecosystems, plant functional traits and burn severity have decisive roles in post-fire vegetation recovery. These traits may reflect plant fitness to fire regimes in the Mediterranean Basin. The aim of this study was to evaluate the effect of burn severity on post-fire vegetation regeneration through plant functional (physiological and regenerative) traits in two Mediterranean ecosystems: one more humid and colder (Cabrera in León province, NW Spain), and another characterized by a longer summer drought (Gátova in Valencia province, SE Spain). A total of 384 and 80 field plots (2 m × 2 m) were fixed in Cabrera and Gátova, respectively. In each burned plot, we quantified burn severity by means of the composite burn index (CBI), differentiating three severity levels (low, moderate, and high), and evaluated post-fire vegetation regeneration one and two years after wildfires. We measured the percentage cover of each species and classified them according to physiological (specific leaf area and N₂-fixing capacity) and regenerative traits (reproductive strategy, bud bank location, and heat-stimulated germination). The main results showed that in Cabrera, burn severity had significant effects on vegetation cover independently of plant functional traits. In Gátova, burn severity effects differed among functional traits. In this site, the cover of plants with low specific leaf area and without heat-stimulation and N₂-fixing capacity was negatively related to burn severity. On the contrary, the cover of N₂-fixers and species with resprouting ability and heat-stimulated germination rose with increasing burn severity. In general, vegetation cover showed a more pronounced increased over time in the more humid area, mainly under the effect of high severity. The results of this research highlighted the importance of the use of plant functional traits as a driver to understand the response of different ecosystems to current fire regimes, which could be relevant for pre- and post-fire management.