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Puccinellia Maritima (puccinellia + maritima)
Selected AbstractsPlant colonization after managed realignment: the relative importance of diaspore dispersalJOURNAL OF APPLIED ECOLOGY, Issue 4 2005MINEKE WOLTERS Summary 1Deliberate breaching of sea defences is frequently practised with the aim of restoring salt-marsh vegetation on previously embanked land. However, experience so far has shown that it may take several years before salt-marsh vegetation is fully established, and it is possible that limited diaspore dispersal plays a role in this. In order to ascertain whether salt-marsh development may be constrained by limited diaspore dispersal, we studied the dispersal of salt-marsh species by tidal water. 2From October 2001 to the end of March 2002 a total of 38 species, of which 18 were salt-marsh species, was trapped in a restoration site and adjacent marsh. Aster tripolium, Limonium vulgare, Puccinellia maritima, Salicornia spp., Spergularia media and Suaeda maritima were the most abundant salt-marsh species, with more than 3 diaspores m,2 trapped during the study period. 3For most species, the number of diaspores trapped was representative of their abundance in nearby vegetation. Hence, despite the potential for long-distance transport by tidal water, our results indicate a predominantly local dispersal of salt-marsh species. 4Synthesis and applications. For the restoration of salt-marsh vegetation after de-embankment, relatively rapid colonization may be expected from pioneer and low-marsh species, provided they are present in a nearby source area and the restoration site is at the appropriate altitude. The establishment of species absent from the adjacent marsh may be dependent on the presence of birds or humans as the main dispersal agents. Breaching of sea defences should preferably take place before or during September, in order to take advantage of the peak in dispersal of salt-marsh species in the first year after breaching. [source] Influence of environmental factors on the growth and interactions between salt marsh plants: effects of salinity, sediment and waterloggingJOURNAL OF ECOLOGY, Issue 3 2000Jonathan M. Huckle Summary 1,Artificial environmental gradients were established in a series of pot experiments to investigate the effect of salinity, sediment type and waterlogging on the growth, and interactions between Spartina anglica and Puccinellia maritima. In each experiment, one environmental variable was manipulated and plants grown in pairwise combinations to examine the effect of the environmental factor on the intensity of intra- and interspecific interactions, quantified using the Relative Neighbour Effect (RNE) index. 2,Puccinellia was found to exert an asymmetric, one-way competitive dominance above ground over Spartina in experiments where gradients of sediment type and waterlogging were established. The intensity of the competition was highest in conditions with the least abiotic stress and lower or non-existent where stress was increased. 3,The intensity of the above-ground competition was greatest in loam and least in sand sediments. Reduction in competitive intensity in sand was accompanied by an increase in below-ground Spartina biomass and it is suggested that the production of rhizomes is a potential mechanism by which this species can expand vegetatively into areas without competition. 4,Interspecific competition on Spartina from Puccinellia also varied in intensity in the waterlogging experiment, being more intense in non-immersed treatments, where abiotic stress was reduced. 5,The competitive dominance of Puccinellia and the competition avoidance mechanism shown by Spartina in these experiments help to explain the successional interactions between the species along environmental gradients in natural salt marsh communities. [source] The role of spatio-temporal heterogeneity in the establishment and maintenance of Suaeda maritima in salt marshesJOURNAL OF VEGETATION SCIENCE, Issue 1 2002Marc Tessier Tutin et al. (1964,1980) Abstract. The effects of disturbance and microtopography on the organization and dynamics of plant communities were studied in a European salt marsh located in the Bay of Mont St. Michel, France. The existence of seed trapping mechanisms was also tested. The study took place in the lower and middle marsh plant communities dominated by the perennials Puccinellia maritima and Halimione portulacoides, respectively and associated with the annual Suaeda maritima. Three treatments were used in series of plots placed in each community: (1) vegetation removal and root destruction to a depth of 10 cm and refilling, (2) non-remnant herbicide treatment without vegetation removal and (3) creation of depressions (20 cm deep). These treatments were compared with adjacent control plots. The first year of the experiment showed that the perennials facilitated the establishment of Suaeda by trapping its seeds. Estimation of cover, density and biomass over 5 yr following the disturbances showed that in the first 2 yr Suaeda dominated the disturbed plots. Thereafter Suaeda was gradually eliminated by competitive exclusion after ca. 3 yr in the zone originally dominated by Puccinellia maritima and after 4 yr in the zone occupied by Halimione portulacoides. Depressions constituted refuge habitats for Suaeda by limiting competition with the perennials but also led to a high risk of mortality with temporal fluctuations in density. Despite a period of investigation limited to 5 yr, our study demonstrated that natural disturbances of various types occurred and influenced the dynamics of Suaeda, Halimione and Puccinellia. We deduced that natural disturbances and microtopography are responsible for the maintenance of the habitat in a state of non-equilibrium by favouring the establishment of both spatial and temporal environmental heterogeneity. These conditions appear to be particularly favourable for the maintenance of annual species such as Suaeda maritima. [source] Interspecific and intraspecific interactions between salt marsh plants: integrating the effects of environmental factors and density on plant performanceOIKOS, Issue 2 2002Jonathan M. Huckle There has been much debate about the role of plant interactions in the structure and function of vegetation communities. Here the results of a pot experiment with controlled environments are described where three environmental variables (nutrients, sediment type and waterlogging) were manipulated factorially to identify their effects on the growth and intensity of interactions occurring between Spartina anglica and Puccinellia maritima. The two species were grown in split-plot planting treatments, representing intraspecific and interspecific addition series experiments, to determine individual and interactive effects of environmental factors and plant interactions on plant biomass. Above-ground growth of both species involved interactions between the environmental and planting treatments, while below-ground, environmental factors affected the biomass irrespective of planting treatments. It was suggested that this difference in growth response is evidence that in our experiment plant interactions between the two species occur primarily at the above-ground level. The intensity of plant interactions varied in a number of ways. First, interactions between Spartina and Puccinellia were distinctly asymmetrical, Puccinellia exerting a competitive effect on Spartina, with no reciprocal effect, and with a facilitative effect of Spartina on Puccinellia in low nutrient conditions. Second, the interactions varied in intensity in different environmental conditions. Interspecific competitive effects of Puccinellia on Spartina were more intense in conditions favourable to growth of Puccinellia and reduced or non-existent in environments with more abiotic stress. Third, intraspecific competition was found to be less intense for both species than interspecific interactions. Finally, the intensity of plant interactions involving both species was more intense above ground than below ground, with a disproportionate reduction in the intensity of interspecific competition below relative to above ground in treatments with less productive sediments and greater immersion. This is interpreted as reflecting a potential mechanism by which Spartina may be able to evade competitive neighbours. [source] | ||||||||||