Abstract. This study attempts to identify Plant Functional Types (PFTs) within the scrub vegetation of the stabilized sand dunes of the Doñana National Park (southwestern Spain) and to explore possible links with ecosystem function. Two 10‐km long transects were sampled along a gradient of water table depth from elevated and dry dunes to a border area close to the salt marsh. A matrix of cover values for 20 woody species × 58 plots and a matrix of 24 morphological and physiological traits × 20 species were analysed by means of DCA and TWINSPAN to identify the main vegetation types and PFTs. In order to know the predominant plant traits, the matrix of 20 species × 58 plots was multiplied by the 24 traits × 20 species matrix. The resulting 24 traits × 58 plots matrix was analysed by means of DCA. The main vegetation types coincide with the previous descriptions of the Park with Juniperus phoenicea woodland and xerophytic species dominating the top of the dunes and hygrophytic species with isolated Quercus suber trees in the depressions. Previous classifications of Mediterranean woody plants resulted in two main PFTs. The present analysis confirmed these two groups: maquis versus garrigue, but added four new groups. The analysis of the traits × plots matrix revealed that the main trend of variation is related to the water table gradient, while the traits related to the species of mature plant communities had little weight in the analysis because these communities are restricted to isolated patches.

The Dune System of Don˜ana National Park (SW Spain) exhibit a mosaic of environmental characteristics, with different plant communities, all under the same Mediterranean climate, creating an interesting field laboratory for the study of plant responses to stressing conditions. Fourteen woody plant populations were selected, belonging to either xerophytic or hygrophytic plant communities on stabilised dunes, where topography causes differences in soil water availability. Plants were tagged and morphological and ecophysiological measurements were recorded in winter and summer of 1999. Seasonal differences in ecophysiological measurements together with morphological variables were used as plant traits to identify the main adaptive responses of the species. Cluster analysis of traits separated three groups of plant strategies: spiny legume species; sclerophyll, and semideciduous species. In addition, another two kind of strategies have been found in the semideciduous group of species, those withstanding water shortages, attaining very negative water potentials, low photochemical efficiency, and leaf proline accumulation in summer, as opposed to those tolerating water deficit, with moderate seasonal differences in water potential, proline content and photochemical efficiency. The results of this study indicate that legume species behave as a different functional group and drought-semideciduous species present different adaptive responses under the same environmental stress. Ecophysiological measurements must be used as plant traits to detect functional groups under Mediterranean climate.

Corema album is a dioecious shrub endemic of the Iberian Peninsula, growing in sandy coastal areas from the North of Galicia to Gibraltar in the South. Hermaphrodite individuals have been found in the southern populations of El Asperillo (Spain) and Vila Real de Santo Antonio (Portugal). In this paper, the role of hermaphroditic individuals in the driest populations of its biogeographical area is discussed and the tradeoff between reproduction and vegetative growth in the three sexual forms is presented. Asperillo site where hermaphrodite individuals were more abundant was selected for this current study. The proportion of hermaphrodite individuals was 1-4%, and male/female sex ratio ranged from 0.9 to 1.1. Hermaphrodite plants had a low number of hermaphrodite inflorescences, in relation to the number of staminate inflorescences. Their ripe fruits were smaller than those of female plants. The reproductive effort was three times higher in female than in male or hermaphrodite plants. The observed interannual oscillation in vegetative elongation was not related to annual rainfall. However, differences existed in growth timing among the three sexual forms, related to the timing of peak investment in reproduction. These results suggest the existence of trade-offs between investment in reproduction and vegetative growth. There were significant differences in leaf water potential among the three sexual forms early in summer, with males showing the less negative and hermaphrodite the most negative potential values. The demand of water for fruit production may explain these differences.

Under natural conditions the overlapping of multiple stressors may initiate coordinated ecophysiological responses in Mediterranean species. Seasonal plasticity may enable plants to better cope with adverse environmental conditions and/or resource variability. In this article, we study the seasonal responses of 12 woody species in two sites of differing water availability, in a Mediterranean-type climate. Plants were measured for water potential, photochemical efficiency, photosynthetic pigments and leaf proline content throughout the year. The results revealed that species presented different ecophysiological strategies, even when sharing the same area. In the xerophytic site, some species suffered severe water stress (-12 MPa and F v /F m lower than 0.3), while others exhibited optimal values of F v /F m and only moderate water stress. All the plants recovered after the first autumn rains. In the hygrophytic site, some sclerophyll species did not exhibit signs of water stress, but did suffer photoinhibition in clear winter days. A plasticity index was calculated to provide an integrated value of species plasticity. In summer, plasticity was higher in the xerophytic site, while in winter it was higher in the hygrophytic site. Ordination analysis of the physiological traits supports the traditional gradient of Mediterranean strategies from drought semideciduous to evergreen sclerophyll species, although spiny legume species formed an independent functional group. The functional responses of species clearly differ among plant communities according to the prevailing site stressors, but no unique pattern emerges. Species combine traits in broader strategies according to previous evolutionary story exhibiting a certain amount of trade among traits, each contributing to alleviate a part of the plant stress.

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