Abstract. The foredune vegetation in the Gulf of Cadiz (SW Spain, S Portugal) was studied by means of morphological characters and functional traits of plants. The 55 vascular species recorded in the area were classified into three functional types: Type I consists mainly of winter annuals of moderate size with soft leaves, showing no presumed adaptations to the dune environment. Plants of Type II are mostly perennials with a below‐ground spreading root network and leaves with presumed adaptations to coastal environmental stress. Type III includes plants mostly capable of being dispersed by sea‐water and of withstanding sand burial. In relatively unstable soil, Type II and Type III plants were found to be more abundant, their relative proportion depending on the dominance of accretion/erosion processes. Increasing cover of Type I plants was associated with relatively more stable soils. The ratios in occurrences of the three types can be used as an indicator of foredune dynamics.

SUMMARY Flood‐tolerant species from natural habitats differ from flood‐intolerant species by being able to make more effective use of nitrate as an alternative electron acceptor to oxygen during periods of partial anaerobiosis. When flooded, tolerant species show marked increases in nitrate‐reductase activity in roots and leaves. A greater ability to synthesize amino‐acids under anoxia was also found in the tolerant species than in the intolerant. It is suggested that these properties enable the flood‐tolerant species to facilitate the re‐oxidation of NADH2 under conditions of anoxia and that this is associated with the greater ability of the species to withstand a reduction in the partial pressure of oxygen.

In Spain, it is estimated that 60% of wetlands have disappeared in the last 50 years. The present study aimed to describe the relationships between loss of wetlands and land-use change in Azuaga County, Central-western Iberian Peninsula where during the period 1896-1996, 94% of the original wetlands disappeared. Forest, scrub, holm oak dehesas and olive groves have become fragmented or disappeared completely, having been substituted by eucalyptus plantations in areas of low productivity and by dry cultivation of herbaceous crops, mainly cereals, in more productive areas. These substitutions have resulted in a homogeneous, coarse-grained landscape with low diversity and high dominance. The type of land-use has depended on the evolution of demographic processes, with high human immigration rates toward the end of the nineteenth century and beginning of the twentieth century, and high emigration rates during the 1960s and 1970s. The mechanization of agriculture and transition from closed to market economy in the second half of the twentieth century also played an essential role in the landscape changes described.

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