Pine afforestation, herriza and wildfire: a tale of soil erosion and biodiversity loss in the Mediterranean region

From a western society’s perspective, wildfires are catastrophic events that jeopardise biodiversity and cause soil erosion, not to mention risk to human lives and properties. However, many Mediterranean-type ecosystems are not only resilient to wildfires but sensitive to the lack of wildfires. This communication focuses on the Mediterranean heathland or herriza as a paradigmatic fire-prone ecosystem to illustrate how most negative impacts allegedly attributed to wildfires actually occur in commercial forestry plantations. They are caused by aggressive forestry practices prior to the wildfire. In natural Mediterranean habitats, such as the herriza, complete wildfire suppression may actually pose a serious threat to biodiversity. The large existing body of scientific knowledge on the relationships of Mediterranean ecosystems with fire should be incorporated into plans and policies dealing with wildfire and conservation to make them more appropriate and efficient. Finally, burned natural areas should not be regarded, or treated, as dead pieces of nature and destroyed ecosystems, but as a transitional stage within the dynamics of Mediterranean-type ecosystems

Soil shapes community structure through fire

7 páginas, 2 figuras, 2 tablas.Recurrent wildWres constitute a major selecting force in shaping the structure of plant communities. At the regional scale, Wre favours phenotypic and phylogenetic clustering in Mediterranean woody plant communities. Nevertheless, the incidence of Wre within a Wre-prone region may present strong variations at the local, landscape scale. This study tests the prediction that woody communities on acid, nutrient-poor soils should exhibit more pronounced phenotypic and phylogenetic clustering patterns than woody communities on fertile soils, as a consequence of their higher Xammability and, hence, presumably higher propensity to recurrent Wre. Results conWrm the predictions and show that habitat Wltering driven by Wre may be detected even in local communities from an already Wre-Wltered regional Xora. They also provide a new perspective from which to consider a preponderant role of Wre as a key evolutionary force in acid, infertile Mediterranean heathlands.This work has been partially supported by projects VAMPIRO (CGL2008-05289-C02-01/BOS) and PERSIST (CGL2006-07126/BOS), Wnanced by the Spanish Ministerio de Ciencia e Innovación, and project P07-RNM-02869, Wnanced by the Junta de Andalucía regional government (Spain). Fieldwork was carried out under permission and complied with legal requirements of the Andalusian regional government.Peer reviewe

Population genetic structure of a sandstone specialist and a generalist heath species at two levels of sandstone patchiness across the Strait of Gibraltar

Many habitat specialist species are originally composed of small, discontinuous populations because their habitats are naturally fragmented or patchy. They may have suffered the long-term effects of natural patchiness. Mediterranean heathlands, a representative habitat in the Strait of Gibraltar region, are associated with nutrient-poor, acidic sandstone soils. Sandstone soil patches in the African side of the Strait (Tangier) are, in general, smaller and more scattered than in the European side (Algeciras). In this study, we analyze the effect of this sandstone patchiness on the population genetic diversity and structure of two Erica species from these Mediterranean heathlands that differ in their edaphic specificity, E. australis, sandstone specialist, and E. arborea, generalist. Average levels of within-population genetic diversity and gene flow between populations were significantly lower in Tangier (high sandstone patchiness) than in Algeciras (low patchiness) for the sandstone specialist, whereas no differences between both sides of the Strait were detected in the edaphic generalist. Since most endemic species in Mediterranean heathlands of the Strait of Gibraltar are sandstone specialists, these results highlight an increased vulnerability to loss of genetic diversity and local extinction of the heathland endemic flora in the Tangier side of the Strait of Gibraltar. © 2014 Gil-López et al.Project BREATHAL (CGL2011-28759/BOS) was financed by the Spanish Ministerio de Ciencia e Innovación.Peer Reviewe

Attract them anyway: benefits of large, showy flowers in a highly autogamous, carnivorous plant species

Reproductive biology of carnivorous plants has largely been studied on species that rely on insects as pollinators and prey, creating potential conflicts. Autogamous pollination, although present in some carnivorous species, has received less attention. In angiosperms, autogamous self-fertilization is expected to lead to a reduction in flower size, thereby reducing resource allocation to structures that attract pollinators. A notable exception is the carnivorous pyrophyte Drosophyllum lusitanicum (Drosophyllaceae), which has been described as an autogamous selfing species but produces large, yellow flowers. Using a flower removal and a pollination experiment, we assessed, respectively, whether large flowers in this species may serve as an attracting device to prey insects or whether previously reported high selfing rates for this species in peripheral populations may be lower in more central, less isolated populations. We found no differences between flower-removed plants and intact, flowering plants in numbers of prey insects trapped. We also found no indication of reduced potential for autogamous reproduction, in terms of either seed set or seed size. However, our results showed significant increases in seed set of bagged, hand-pollinated flowers and unbagged flowers exposed to insect visitation compared with bagged, non-manipulated flowers that could only self-pollinate autonomously. Considering that the key life-history strategy of this pyrophytic species is to maintain a viable seed bank, any increase in seed set through insect pollinator activity would increase plant fitness. This in turn would explain the maintenance of large, conspicuous flowers in a highly autogamous, carnivorous plant

Mediterranean Heathland as a Key Habitat for Fire Adaptations: Evidence from an Experimental Approach

Some fire ecology studies that have focused on garrigue-like vegetation suggest a weak selective pressure of fire in the Mediterranean Basin compared to other Mediterranean-type regions. However, fire-prone Mediterranean heathland from the western end of the Mediterranean Basin has been frequently ignored in the fire ecology literature despite its high proportion of pyrogenic species. Here, we explore the evolutionary ecology of seed traits in the generalist rockrose Cistus salviifolius L. (Cistaceae) aiming to ascertain the role of the Mediterranean heathland for fire adaptations in the Mediterranean Region. We performed a germination experiment to compare the relationship of seed size to (i) heat-stimulated germination, (ii) dormancy strength, and (iii) heat survival in plants from 'high-fire' heathland vs. 'low-fire' coastal shrubland. Germination after heat-shock treatment was higher in large seeds of both 'high-fire' and 'low-fire' habitats. However, dormancy was weaker in small seeds from 'low-fire' habitats. Finally, seed survival to heat shock was positively related to seed size. Our results support that seed size is an adaptive trait to fire in C. salviifolius, since larger seeds had stronger dormancy, higher heat-stimulated germination and were more resistant to heat shock. This seed size-fire relationship was tighter in 'high-fire' Mediterranean heathland than 'low-fire' coastal shrubland, indicating the existence of di fferential fire pressures and evolutionary trends at the landscape scale. These findings highlight the Mediterranean heathland as a relevant habitat for fire-driven evolution, thus contributing to better understand the role of fire in plant evolution within the Mediterranean region

Optimization of an Ultrasound-Assisted Extraction Method for the Analysis of Major Anthocyanin Content in Erica australis Flowers

Erica australis plants have been used in infusions and folk medicine for years for its diuretic and antiseptic properties and even for the treatment of infections. In addition, a recently published thorough study on this species has demonstrated its antioxidant, antibiotic, anti-inflammatory, anticarcinogenic and even antitumoral activities. These properties have been associated with the high content of anthocyanins in E. australis leaves and flowers. The aim of the present research is to optimize an ultrasound-assisted extraction methodology for the recovery of the anthocyanins present in E. australis flowers. For that purpose, a Box Behnken design with response surface methodology was employed, and the influence of four variables at different values was determined: namely, the composition of the extraction solvents (0–50% MeOH in water), the pH level of those solvents (3–7), the extraction temperature (10–70 C), and the sample:solvent ratio (0.5 g:10 mL–0.5 g:20 mL). UHPLC-UV-vis has been employed to quantify the two major anthocyanins detected in the samples. The extraction optimum conditions for 0.5 g samples were: 20 mL of solvent (50% MeOH:H2O) at 5 pH, with a 15 min extraction time at 70 C. A precision study was performed and the intra-day and inter-day relative standard deviations (RSDs) obtained were 3.31% and 3.52%, respectively. The developed methodology has been successfully applied to other Erica species to validate the suitability of the method for anthocyanin extraction.This work has been supported by the project "EQC2018-005135-P" (Equipment for liquid chromatography by means of mass spectrometry and ion chromatography) of the State Subprogram of Research Infrastructures and Technical Scientific Equipment

Ecología, biogeografía y diversidad de los brezales del Estrecho de Gibraltar

Los brezales sobre suelos ácidos son las comunidades leñosas dominantes en la Europa atlántica. También pueden encontrarse, aunque de forma más aislada, en la Cuenca Mediterránea. Se ha realizado un estudio biogeográfico de la subfamilia Ericoidae, para determinar las afinidades ecogeográficas de las especies de esta subfamilia (i.e. brezos) a escala europea y de la Cuenca Mediterránea. La región del Estrecho de Gibraltar constituye uno de los ejemplos más notables de brazales en el oeste de la Cuenca. Se ha estudiado la ecología de estas comunidades leñosas mediante la selección de 63 puntos de muestreo en ambos lados del Estrecho de Gibraltar. Se han reconocido diferentes tipos de brezales según su estructura y composición florística y se han relacionado con una seria de variables ambientales mediante la aplicación de técnicas multivariantes. Se ha detectado una tendencia principal de variación de estas comunidades relacionada con las características de acides y fertilidad de los sustratos. Esta tendencia se ha observado de forma paralela en ambos lados del Estrecho. Se han determinado los patrones de variación de la diversidad ecológica, corológica y taxonómica (como componentes de la biodiversidad) de estas comunidades a lo largo del gradiente de acidez y fertilidad. Las diferencias a este respecto entre ambos lados del Estrecho se han relacionado con el modelo de disposición espacial más fragmentado y aislado de los suelos ácidos en la península tingitana y con unos niveles superiores de la perturbación de la vegetación marroquí. Los procesos ecológicos e históricos de la región del Estrecho de Gibraltar se reflejan en los patrones de diversidad, estructura y composición florística de sus comunidades leñosas. Se han comparado estos patrones con los de otras comunidades mediterráneas del Globo y con los de los brazales templados de Europa con el fin de situar los brazales del Estrecho de Gibraltar en el contexto de la vegetación mediterránea. Además en algunas comunidades del estudio de la diversidad se ha ampliado a todas las especies vegetales macroscópicas (vasculares y no vasculares) a la escala 0,1 Ha con el fin de detectar patrones en los distintos estratos. La regeneración de la vegetación después del fuego es una característica común al conjunto de las comunidades mediterráneas así como al conjunto de los brezales del mundo. En la zona de estudio, el fuego ha sido una de las variables ambientales más determinantes de la estructura y composición de las comunidades. Se ha realizado un estudio descriptivo de la regeneración de un brezal después de un incendio, determinando la importancia de las diferentes estrategias de regeneración de las especies leñosas en el restablecimiento de la comunidad y la relevancia de las especies herbáceas anuales y perennes en la ecología de la regeneración. Finalmente se ha llevado a cabo un estudio de las poblaciones de los brezos más frecuentes en situaciones contrastadas dentro del gradiente de acidez y fertilidad. Se ha observado una segregación ecológica de las diferentes especies de brezo en las comunidades. Este patrón se repite a ambos lados del Estrecho, con algunas diferencias y se ha explicado mediante la existencia de fenómenos de competencia y estrategias de coexistencia. El modelo espacial de "islas" ácidas y los mayores niveles de perturbación en la vegetación marroquí se sugieren como las dos causas fundamentales de las diferencias norte-sur en la segregación ecológica de los brezos

Ecological distribution of four co-occurring Mediterranean heath species

12 pages, 4 figures, 5 tables, 64 references.Erica australis, E. scoparia, E. arborea and Calluna vulgaris are the most abundant heath species on acid, sandstone-derived soils of the Strait of Gibraltar region (southern Spain and northern Morocco). Despite their apparently similar ecological requirements, these four species are somewhat ecologically segregated. Erica australis is abundant only on poor, shallow soils, with a high content in soluble aluminium, generally on mountain ridges and summits. Erica scoparia becomes dominant on deeper sandstone soils with lower aluminium. Calluna vulgaris coexists with these Erica species in communities under low or no tree cover. In the Spanish side of the Strait (Algeciras), Erica arborea tends to be relegated to communities under moderate to dense tree cover, whereas this species is more abundant and widespread in the Moroccan side (Tangier). Tolerance to extreme physical conditions - high aluminium and dense tree cover - and interspecific competition seem to explain the ecological distribution of these four heath species in the Strait of Gibraltar region. The more fragmented pattern of sandstone patches and higher disturbance levels in Tangier might account for the differences in the patterns of ecological distribution of these four heath species between both sides of the Strait of Gibraltar.This study was supported by the DGICYT (projects 91/894, 95/551 and APC-93/128) and DGES (project PB97/1177).Peer reviewe

Plant diversity patterns in the Aljibe Mountains (S. Spain): a comprehensive account

21 pages, 6 figures, 6 tables, 55 references.The Aljibe Mountains are located in the southern tip of the Iberian Peninsula and have a remarkable biogeographical interest. The complete plant species list (trees, climbers, shrubs, perennial and annual herbs, ferns, lichens, bryophytes and macroscopic algae) was recorded in four 0.1 ha plots from each of the most representative community types (Quercus suber woodland, Q. canariensis forest, open heathland and Q. coccifera shrubland). Up to 119 plant species were found in total in the Q. suber woodland plot. The diversity of woody plants was analysed from 44 samples of cover (100 m line), and the herbaceous layer was explored in 200 quadrats (of 0.5 x 0.5 m). Three biodiversity components (species richness, endemism, and taxonomic singularity) were evaluated in both shrub and herbaceous layers. Open heathlands showed the highest richness of endemic species, both woody and herbaceous. The highest number of woody species was found in the evergreen Q. suber woodland, and of herbaceous species in the semi-deciduous Q. canariensis woodland. Taxonomic singularity was higher in Q. canariensis woodlands and Q. coccifera shrublands for woody species, but there were no significant differences in the herbaceous layer. Local species diversity of heathlands in this region resembles that of South African heathlands (fynbos), despite the obvious geographic and floristic distance, and contrasts with the low diversity of biogeographically closer, European temperate heathlands. The Aljibe Mountains show high diversity values for different life forms (from trees to mosses) and spatial scales (from community to region), and are rich in endemic species. Thus, this area should be recognised as a relevant unit within the Mediterranean plant diversity hot spots.The Spanish DGICYT (grants 91/894 and 95/551) and DGES (grant 97/1177), and the Andalusian CMA (Hozgarganta research contract) supported the study.Peer reviewe