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Sand Dune Area (sand + dune_area)
Selected AbstractsHerbivory and Abiotic Factors Affect Population Dynamics of Arabidopsis thaliana in a Sand Dune AreaPLANT BIOLOGY, Issue 5 2005A. Mosleh Arany Abstract: Population dynamics of the annual plant Arabidopsis thaliana (L.) Heynh. were studied in a natural habitat of this species on the coastal dunes of the Netherlands. The main objective was to elucidate factors controlling population dynamics and the relative importance of factors affecting final population density. Permanent plots were established and plants were mapped to obtain data on survival and reproductive performance of each individual, with special attention to herbivore damage. In experimental plots we studied how watering, addition of nutrients, artificial disturbance, and natural herbivores affected survival and growth. Mortality was low during autumn and early winter and high at the time of stem elongation, between February and April. A key factor analysis showed a high correlation between mortality from February to April and total mortality. The specialist weevils Ceutorhyncus atomus and C. contractus (Curculionidae) were identified as the major insect herbivores on A. thaliana, reducing seed production by more than 40 %. These herbivores acted in a plant size-dependent manner, attacking a greater fraction of the fruits on large plants. While mortality rates were not affected by density, fecundity decreased with density, although the effect was small. Adding water reduced mortality in rosette and flowering plant stages. Soil disturbance did not increase seed germination, but did have a significant positive effect on survival of rosette and flowering plants. Seed production of A. thaliana populations varied greatly between years, leading to population fluctuations, with a small role for density-dependent fecundity and plant size-dependent herbivory. [source] Sex Ratio of Some Long-Lived Dioecious Plants in a Sand Dune AreaPLANT BIOLOGY, Issue 5 2004T. J. de Jong Abstract: In dioecious plants the fraction of males among flowering plants in the field (the secondary sex ratio) is the result of the fraction of males in the seeds (the primary sex ratio) and the subsequent survival and age at first reproduction of the two genders. It has been assumed that survival and age at first reproduction are the main determinants of biased secondary sex ratio but, especially for long-lived perennials, few data are available. We address this issue for natural populations of four long-lived perennials in a dune area. In Asparagus officinale and Bryonia dioica, the secondary sex ratio was unbiased. In Salix repens the secondary sex ratio was female-biased (0.337). Hippophae rhamnoides populations were male-biased; the average sex ratio of flowering plants was 0.658, while the fraction of males varied between 0.39 near the sea to 0.84 at the inland side of the dunes. The primary sex ratio was estimated by germinating seeds and growing plants under favourable conditions with minimal mortality. In S. repens the primary sex ratio in seeds was variable among mother plants and was, on average, female-biased (0.289). This is close to the secondary sex ratio, suggesting that the female bias already originates in the seed stage. In Hippophae rhamnoides the primary sex ratio was slightly male-biased (0.564). We argue that in this species, apart from the primary sex ratio, higher mortality and a later age at first reproduction for females contribute to the strong male bias among flowering plants in the field. [source] A new species of Aeschynomene L. (Leguminosae, Papilionoideae) from a continental sand dune area in north-eastern BrazilBOTANICAL JOURNAL OF THE LINNEAN SOCIETY, Issue 4 2008LUCIANO P. QUEIROZ Aeschynomene sabulicola L.P. Queiroz & D. Cardoso is proposed as a new species of the section Ochopodium. This new species seems to be related to the series Viscidulae, as it presents herbaceous, slender branches, densely covered by viscid glandular hairs. However, it possesses fruits much larger than expected for this series. Aeschynomene sabulicola can be diagnosed by the erect habit, reaching c. 3.5 m high, inflorescences divaricate and horizontal with remote flowers, and fruits with only one subreniform article, this measuring 13,14 × 7,8 mm. The species occurs only in a continental sand dune area along the middle São Francisco River basin in the State of Bahia, north-eastern Brazil. © 2008 The Linnean Society of London, Botanical Journal of the Linnean Society, 2008, 157, 749,753. [source] | ||||||||||