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Aviso legal: los contenidos de esta publicación podrán ser reutilizados, citando la fuente y la fecha, en su caso, de la última actualización., Esta Guía fue realizada en el año 2020 en el marco del poryectos LIFE INVASAQUA (LIFE17 GIE/ES/000515) Aquatic Invasive Alien Species of Freshwater and Estuarine Systems: Awareness and Prevention in the Iberian Peninsula, financiado por el Programa LIFE de la Comisión Europea.

Ponencia presentada a la 51 Reunión Científica de la SEEP celebrada en la Escuela Superior de Ingenieros Agrónomos de la Universidad Pública de Navarra entre el 14 y el 18 de mayo de 2012. El trébol blanco es una de las leguminosas más extendidas en zonas húmedas. Los bosques de ribera se caracterizan por una vegetación herbácea aprovechada ocasionalmente por el ganado, y particularmente sensible a la invasión de especies vegetales que pueden alterar su diversidad. El objetivo de este trabajo fue determinar cómo afecta la hojarasca de especies arbóreas nativas e invasoras en el crecimiento de la herbácea nativa Trifolium repens. Para ello se realizó un ensayo en invernadero con hojarasca de invasoras Ailanthus altissima, Robinia pseudoacacia, Ulmus pumila y nativas: Populus alba, Populus nigra, Ulmus minor, en cuatro momentos de descomposición. Los resultados muestran una reducción en el crecimiento de T. repens, tanto de la parte aérea como de la raíz, con todos los tratamientos de hojarasca (especies y tiempo de descomposición). El porcentaje de emergencia no se ve afectado de forma significativa por ninguno de los tratamientos. Por tanto el efecto de la hojarasca tendría mayor intensidad en el crecimiento de las plantas que en las fases germinativas. White clover is one of the most widespread legumes in wet areas. Riparian forests are characterized by a herbaceous layer occasionally exploited by cattle and particularly sensitive to the invasion of plant species which may alter its diversity. The aim of this study was to determine the effect of invasive and native tree leaf litter in several decomposition phases, in the growth of the herbaceous Trifolium repens. A trial was conducted in a greenhouse with litter of invasives Ailanthus altissima, Robinia pseudoacacia, Ulmus pumila and natives: Populus alba, Populus nigra, Ulmus minor, in four decomposition phases. The results showed a reduction in the growth of T. repens with all litter treatments affecting both shoot and root growth. The percentage of emergency was not significantly affected by either treatment. Therefore, the effect of litter would have higher intensity in the growth of plants in the germ stage. Este trabajo ha sido subvencionado por la Comunidad de Castilla-La Mancha, proyecto POII10-0179-4700.

12 páginas, 4 figuras y 4 tablas, 1 Quercus coccifera, a slow-growing, evergreen oak, grows in contrasting environments in the Mediterranean Basin. Habitat-based selection may have promoted divergence between populations with respect to phenotypic plasticity and genetic variability. 2 We tested the hypothesis that populations of the Q. coccifera originating from a rock outcrop, a continental garrigue formation and an oceanic forest would differ in their plastic response to light intensity. Plants from these populations were grown from acorns in a common garden at 100% and 20% full sunlight. Light response analysis was based on photochemical efficiency, xanthophyll pool, nutrient allocation, growth, crown architecture and light absorption. 3 Light-responsive characters ranged from the subcellular to the whole-plant level. The greatest divergences between sun and shade phenotypes were observed in leaf size, leaf angle and leaf area ratio. However, plasticity in these traits depended on plant provenance. 4 Regardless of the level of organization, populations were invariably ranked in the same order of plasticity when averaged over light-responsive features, with plants originating from the rock outcrop showing the least plasticity and those from the forest the largest. The forest population also had the greatest genetic variability with respect to the isoperoxidase polymorphism. 5 Among populations, plants originating from the phosphorus-deficient rock outcrop contained 30% more P per unit dry weight. Plants from the forest population had 5% more photoprotective xanthophylls, 30% larger total leaf area, with less lobed and larger leaves and a differential plasticity in leaf azimuth. 6 Differences among populations suggested ecotypic differentiation towards less phenotypic plasticity in the most homogeneous light environments. The ecological breadth of the species seemed to be derived not only from its tolerance of Mediterranean conditions but also from the specialization of its populations in contrasting habitats., The research was financed by the CICYT (CLI97-0735-CO3-01/02). We sincerely thank Mr A. Jordán and Dr M. A. S. Clemente for the analyses of the soil samples from the provenance sites, and Viveros Barbol for technical assistance. We are grateful to Dr F. I. Pugnaire and Dr L. Ramírez for their valuable comments.