Acute and early symptoms of forest dieback linked to climate warming and drought episodes have been reported for relict Abies pinsapo Boiss. fir forests from Southern Spain, particularly at their lower ecotone. Satellite, orthoimages, and field data were used to assess forest decline, tree mortality, and gap formation and recolonization in the lower half of the altitudinal range of A. pinsapo forests (850-1550 m) for the last 36 years (1985-2020). Field surveys were carried out in 2003 and in 2020 to characterize changes in stand canopy structure and mortality rates across the altitudinal range. Time series of the Normalized Difference Vegetation Index (NDVI) at the end of the dry season (derived from Landsat 5 and 7 imagery) were used for a Dynamic Factor Analysis to detect common trends across altitudinal bands and topographic solar incidence gradients (SI). Historical canopy cover changes were analyzed through aerial orthoimages classification. Here we show that extensive decline and mortality contrast to the almost steady alive basal area for 17 years, as well as the rising photosynthetic activity derived from NDVI since the mid-2000s and an increase in the forest canopy cover in the late years at mid and high altitudes. We hypothesized that these results suggest an unexpected resilience in A. pinsapo forests to climate change-induced dieback, that might be promoted by compensation mechanisms such as (i) recruitment of new A. pinsapo individuals; (ii) facilitative effects on such recruitment mediated by revegetation with other species; and (iii) a ‘release effect’ in which surviving trees can thrive with fewer resource competition. Future research is needed to understand these compensation mechanisms and their scope in future climate change scenarios.

In this study we combine information from aerial LIDAR and hemispherical images taken in the field with ForeStereo—a forest inventory device—to assess the vulnerability and to design conservation strategies for endangered Mediterranean fir forests based on the mapping of fire risk and canopy structure spatial variability. We focused on the largest continuous remnant population of the endangered tree species Abies pinsapo Boiss. spanning 252 ha in Sierra de las Nieves National Park (South Andalusia, Spain). We established 49 sampling plots over the study area. Stand structure variables were derived from ForeStereo device, a proximal sensing technology for tree diameter, height and crown dimensions and stand crown cover and basal area retrieval from stereoscopic hemispherical images photogrammetry. With this information, we developed regression models with airborne LIDAR data (spatial resolution of 0.5 points∙m−2). Thereafter, six fuel models were fitted to the plots according to the UCO40 classification criteria, and then the entire area was classified using the Nearest Neighbor algorithm on Sentinel imagery (overall accuracy of 0.56 and a KIA-Kappa Coefficient of 0.46). FlamMap software was used for fire simulation scenarios based on fuel models, stand structure, and terrain data. Besides the fire simulation, we analyzed canopy structure to assess the status and vulnerability of this fir population. The assessment shows a secondary growth forest that has an increasing presence of fuel models with the potential for high fire spread rate fire and burn probability. Our methodological approach has the potential to be integrated as a support tool for the adaptive management and conservation of A. pinsapo across its whole distribution area (<4,000 ha), as well as for other endangered circum-Mediterranean fir forests, as A. numidica de Lannoy and A. pinsapo marocana Trab. in North Africa.

Los ecosistemas litorales están fuertemente amenazados por el aumento del nivel del mar, las inundaciones y la litoralización de la población. Aunque se ha intensificado el esfuerzo por declarar áreas protegidas costeras, estas quedan fragmentadas en teselas circundadas por territorios artificalizados. La conectividad entre estas áreas protegidas es por tanto la garantía de la continuidad de los servicios ecosistémicos que proveen. Se propone un modelo para la evaluación de la eficacia potencial del sistema continuo de las áreas protegidas costeras en base al conocimiento de su flora y vegetación. El grado de efectividad pretende ser un indicador para la adopción de medidas de planificación territorial conducentes al fortalecimiento de la red como medida de salvaguarda de la biodiversidad. Para probar el modelo propuesto se ha elegido la costa de Andalucía (S de España), territorio bañado por el Mediterráneo y el Atlántico, susceptible de importantes impactos. Este segmento de costa ha sido sometido durante los últimos 60 años a fuertes presiones de origen antrópico.que han fragmentado y alterado la estructura, composición y funcionalidad de los ecosistemas litorales. Todo ello pone en riesgo tanto los valores que sirvieron para la declaración de un status de protección como la conectividad entre ecosistemas que garanticen la persistencia de sus servicios ecosistémicos. La metodología propuesta para medir la eficacia potencial del sistema se sustenta en el grado de protección legal, el valor fitocenótico y el grado de artificialización. A partir de la integración de los valores obtenidos se ha calculado la consistencia de los nodos y en definitiva la efectividad en red. La aplicación de este método pone de relevancia cuales son las áreas protegidas  más vulnerables ante las deficiencias de la red, en especial por las dificultades de conectividad.