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ABSTRACT. Ecology and structure of Drosophyllum lusitanicum (L.) Link populations in the south- western of the Iberia!, Peninsula. The population size and the demographic structure of the autogamous and nautochoric Drosophyllum lusitanicum were studied in two areas in the South-western Iberian Peninsula. Its coenological character is documented by a synoptic phytosociological table, based upon the published relevés and new data. In the Serra de Monchique (Portugal), the distribution was mapped. 21 populations are growing there with an average size of 165 individuals. In the Campo de Gibraltar (Spain), the biggest population with severa] thousands of individuals occurs in the Sierra del Aljibe. Plant size, rosette diameter and lignification rate from 700 measured individuals are used as indirect indicators for the age-structure in 19 populations.Drosophyllum has a certain pioneer character. It occurs mostly in open Ericion umbellatae-heathland communities (Stauracantho-Drosophylletum. Querco lusitanicae-Stauracanthetutn, Genisto tridentis- Stauracanthetutn etc.). It is able to colonize disturbed habitats like roadside verges and fire prevention strips and is an apophyt in the Drosophyllo-[Stauracanthenionl-basal community. As a re-seeder the species is favoured by fire events of medium frequency. In open Myrto-Quercetum suberis-woodland and in dense Erica austraiis-heathland, large and tall-growing specimens predominate; there the populations are over-aged. Some deficits in the knowledge of its reproductive biology and further research topics are outlined and the needs for conservation efforts in the Portuguese study area are strengthened.Key words. Fleathland vegetation, Ericion umbellatae, Portugal, Serra de Monchique, Spain, phytosociology, endemism.RESUMEN. Ecología y estructura de poblaciones de Drosophyllum lusitanicum (L.) Link en el suroeste de la Península Ibérica. Drosophyllum lusitanicum es una planta autógama y nautocórica cuyo tamaño y estructura de población han sido estudiados en dos áreas del suroeste de la Península Ibérica. Su carácter cenológico se documenta mediante una tabla fitosociológica sintética basada en inventarios ya publicados y datos nuevos. En la Sierra de Monchique (Portugal) se cartografían 21 poblaciones cuyo tamaño medio es de 165 individuos. Sin embargo, en el Campo de Gibraltar (España), se encontró la población de mayor tamaño, con varios miles de individuos en la Sierra del Aljibe. Aquí se estudió el tamaño de las plantas, el diámetro de la roseta basal y el grado de lignificación de 700 individuos, lo que se utilizó como indicador indirecto de la estructura de edades de 19 poblaciones. Drosophyllum lusitanicum tiene un cierto carácter pionero. Se presenta mayoritariamente en los brezales aclarados de Ericion umbellatae (Statiracantho-Drosophylletum, Querco lusitanicae- Stauracanthetum, Genisto tridentis-Stauracanthetum, cte.). Es capaz de colonizar medios alterados, como cunetas de carreteras y cortafuegos, y es un apófito en las comunidades basales de Drosophyllo- [Stauracanthenion], siendo además esta especie favorecida por los frecuentes incendios de la zona. En los alcornocales abiertos de Myrto-Quercetum suberis y en los brezales densos de Erica australis predominan  los individuos grandes, siendo éstas poblaciones maduras. Finalmente, se aportan algunos datos poco conocidos de su reproducción y ecología que indican la necesidad de un mayor esfuerzo para la conservación del área portuguesa estudiada.Palabras clave. Brezales, Ericion umbellatae, Portugal, Serra de Monchique, España, fitosociología, endemismos.

Until now, the vegetation of seasonal wetlands in South America has only been studied on local to regional scales. A synoptic view is lacking and the distribution of vegetation types remains unknown. Hence we attempt here to detect fl oristic patterns on the spatial dimension of the subcontinent and to identify the environmental factors behind them. All plot-related fl oristic data (phytosociological relevés) available to us were collected and stored in a TURBOVEG-database. The study area included both extratropical South America (austral-temperate and subantarctic climatic zones) and the orotropical biome of the Andean Highlands, because the amphibic habitats in the two areas have some taxa in common. Tropical lowlands were more dissimilar and thus were excluded. In total we found 573 vegetation samples in 28 bibliographic sources, published between 1960 and 2008. To achieve a consistent nomenclature was a major problem, and the taxonomic treatment of a number of habitat specifi c taxa is obviously in need of improvement. Classifi cation and ordination were performed with the total data set as well as just the diagnostic taxa. The fl oristic structure was analysed using non-metric multidimensional scaling (nMDS) and procrustes rotation techniques to compare species combinations at the species and genus levels. The interpretation of the results is limited by the substantial fl oristic and ecological heterogeneity of the data (varying plot size, plots including an inundation gradient etc.) and by the spatially uneven distribution of the data. The classifi cation revealed a higher diversity of communities than expected: 11 clusters with precise species combinations, ecology and distribution emerged from the classifi cation: A) Plagiobothryo-Acaenion platyacanthae and B) Pration repentis are distributed in Southern Patagonia in seasonal lagoons, respectively on inundated turfs. Moorland pools and inundated bog hollows in hard cushion mires of the Andean belt have a number of genera in common, but separate on the species level into C) Muhlenbergia fastigiata-Distichlis humilis-communities in the semi-desert highlands of NW Argentina, D) Gentiana sedifolia-Carex bonplandii and Gentiano-Oritrophion-communities in the Super-Páramo belt of Venezuela, E) the Lilaeopsion andinae in the altiplano extending from S Peru to NE Chile and NW Argentina, and F) Limosella-communities ranging from E Bolivia to Central Andean Peru. Lakeshores in the super-forest belt of the wet tropical Andes and in the mountainous parts of extratropical South America are colonized by the Crassuletalia peduncularis-venezuelensis (cluster G), the amphibic zone of lakes in the temperate climate of Chile and Argentina by Littorellion australis-and Senecioni zosteraefolii-Eleocharietalia-communities (cluster H). The vegetation of vernal pools in Mediterranean Chile has been poorly studied until now, but some communities are recorded from the transition zone to temperate Chile. They are grouped in Juncion planifolii (cluster I). Seasonal wetlands in fl oo...