Se realiza la caracterización geoecológica de una formación riparia de galería de taraje común (Tamarix gallica) en el Arroyo Aceitero (provincia de Sevilla), usando dos aproximaciones: 1) el uso combinado de los valores indicadores de Ellenberg y las coberturas, propuesto por Laguna (2012), y 2) el método Fi/Fa (Interactividad Fitoindicación/Fitoacción) de Meaza y Cuesta (2010). Previamente, se realiza un análisis de estructura y dinámica mediante el uso combinado de algunos estadísticos y la propuesta de clasificación sociológica de pies de formaciones leñosas empleado por el Sistema Agro-Forestal (Harold, 1984). Ambos métodos indican que el tarajal muestreado es una comunidad vegetal que combina especies higrófilas y nitrófilas, estando de hecho dominada por plantas higronitrófilas. Se concluye que ambas aproximaciones metodológicas pueden usarse de modo complementario.
Limonium angustebracteatum is a halophyte endemic to the E and SE Iberian Peninsula with interest in conservation. Salt glands represent an important adaptive trait in recretohalophytes like this and other Limonium species, as they allow the excretion of excess salts, reducing the concentration of toxic ions in foliar tissues. This study included the analysis of the salt gland structure, composed of 12 cells, 4 secretory and 8 accessory. Several anatomical, physiological and biochemical responses to stress were also analysed in adult plants subjected to one month of water stress, complete lack of irrigation, and salt stress, by watering with aqueous solutions of 200, 400, 600 and 800 mM NaCl. Plant growth was inhibited by the severe water deficit and, to a lesser extent, by high NaCl concentrations. A variation in the anatomical structure of the leaves was detected under conditions of salt and water stress; plants from the salt stress treatment showed salt glands sunken between epidermal cells, bordered by very large epidermal cells, whereas in those from the water stress treatment, the epidermal cells were heterogeneous in shape and size. In both, the palisade structure of the leaves was altered. Salt excretion is usually accompanied by the accumulation of salts in the foliar tissue. This was also found in L. angustebracteatum, in which the concentration of all ions analysed was higher in the leaves than in the roots. The increase of K+ in the roots of plants subjected to water stress was also remarkable. The multivariate analysis indicated differences in water and salt stress responses, such as the accumulation of Na and Cl, or proline, but K+ homeostasis played a relevant role in the mechanism of tolerance to both stressful conditions.
In order to achieve certain targets of the Global Strategy for Plant Conservation (GSPC), countries should aim to have at least 75% of their threatened species preserved in ex situ genetically representative collections, preferably in the country of origin, and at least 20% of the threatened species must be available for recovery plans and restoration programs (Target 8). Assessing the conservation value of ex situ collections is needed in order to identify the gaps in gene banks and to determine the baseline situation. Selection of the target species for conservation followed the Regional Responsibility criterion, as the first-order of priority at the local level with highest ranking given to species whose distribution is endemic to the study area. Data analysis was performed on 85 species listed in the Valencian Catalog of Threatened Plant Species (VCTPS) stored in the Germplasm Bank Collections of Valencian Flora, Spain. Our results show that conservation value of an ex situ collection will depend on whether the analysis is based on the representation of species (i.e. the presence or absence of species in an ex situ collection) or based on their representativeness (i.e. how well the collected and stored natural populations represent the “theoretical” species genetic diversity and what is the potential to produce plants for recovery actions, summarized in the proposed index R4). For 85 species listed in VCTPS the existing ex situ seed bank collections keep samples of 91.8% (78 species), indicating good representation. However, the criteria accounting for number of populations collected and quality of the stored germplasm revealed that less than 50% of the listed species are properly preserved in the ex situ collections.
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