Niche breadth rather than reproductive traits explains the response of wetland monocotyledons to land‐cover change

Question: We hypothesised that, even within the same plant functional group, there are specific distributions in land-cover classes and with land-cover change that are associated with niche breadth rather than reproductive strategy, and that the broader the niche of the species the better they cope with different land-cover classes and changes over time. Location: The Llobregat Delta (Barcelona, Spain). Methods: We analysed the distribution pattern of eight coexisting wetland perennial monocotyledons within human disturbance classes (obtained from the classifica- tion of land-cover categories in relation to their level of human disturbance) and changes in such classes from 1956 to 1999. We then compared species regional abundance and distribution patterns with seed dispersal type (wind dispersed versus non-wind dispersed species), vegetative spread (tussock versus caespitose-running spe- cies), and niche breadth (the number of phytosociological alliances in which each species is found). Results: Regional abundance of the species was positively related to niche breadth, but was independent of re- productive traits. Similarly, distribution in human distur- bance classes and their changes were associated with niche breadth rather than reproductive traits. In general, the more specialist the species, (i) the more they are concen- trated in natural habitats, (ii) the less land-cover changes they are able to cope with, and (iii) the more they are restricted to stable change types, particularly to long- standing natural areas. Conclusions: Ecological plasticity rather than dispersal capacity of dominant perennial monocotyledons deter- mines their regional abundance and their ability to cope with recent and future land-cover changes in Mediterra- nean wetlands. As habitat specialists are less resistant to landscape change than generalists, floristic homogenisation may progress in these habitats with the likely scenario of increasing land-cover turnoverPeer reviewe

Variação temporal de características morfológicas de folhas em dez espécies do Parque Nacional da Restinga de Jurubatiba, Macaé, RJ, Brasil Temporal variation of morphological leaf traits in ten species from Restinga of Jurubatiba National Park, Macaé, Rio de Janeiro State, Brazil

Ordenar espécies em relação a um contínuo de variação de características foliares pode ser útil para inferir sobre a suscetibilidade de uma comunidade a alterações na disponibilidade de recursos e/ou condições ambientais ao longo do tempo. Dez espécies lenhosas de restinga foram acompanhadas quanto à variação temporal de atributos morfológicos foliares. Folhas de dez espécies de restinga foram coletadas nos meses de fevereiro, abril e agosto ao longo de três anos para caracterização da variação temporal da massa de folha por unidade de área (MFA), suculência (SUC), espessura (ESP) e densidade (DEN). As espécies apresentaram uma tendência de valores mais elevados para as características estudadas nos meses mais secos. A partir da comparação sazonal e interanual da MFA, SUC, ESP e DEN sugerimos que a natureza das respostas das plantas à heterogeneidade temporal na disponibilidade de água foi convergente, independentemente do padrão fenológico de produção foliar e filogenia. Portanto, a similaridade observada entre as espécies na dinâmica temporal dos atributos foliares indica a disponibilidade hídrica como um fator determinante para o sucesso na ocupação das planícies arenosas costeiras do norte fluminense.<br>Ranking species in relation to a continuum of leaf-trait variation can be useful to infer community susceptibility to changes in resource availability and/or environmental conditions over time. Leaves of ten woody restinga species were sampled in February, April and August over a period of 3 years to characterize temporal variability of leaf mass per area (LMA), succulence (SUC), thickness (THI) and density (DEN). The species showed a trend toward higher leaf-trait values in dry months during the three-year study. Based on seasonal and interannual comparison of LMA, SUC, THI and DEN we suggest that plant responses to temporal heterogeneity in water availability were convergent, independent of leaf phenological patterns and phylogeny. Thus, the similarity observed among species in temporal dynamics of leaf traits points to water availability as a limiting factor for the success of sandy-coastal-plain occupation in northeastern Rio de Janeiro