Seed banks and seed population dynamics of halophytes

In this review I will describe the importance of seed banks and the population dynamics of seeds on the distribution of species in saline habitats. The main questions being examined in this review include: 1. Does the seed bank represent the flora of the entire salinity gradient or is it restricted to the species in each zonal community? 2. Is the size and species composition of the persistent seed bank regulated by the degree of salt stress in habitats along an environmental gradient? 3. Does the population dynamics of seeds influence the temporal and spatial distribution of plant species in saline habitats? Seed banks may be transient or persistent depending upon the physiological responses of species and the soil environment in which the seeds are found. The formation of zonal communities in salt marsh environments is affected by changes in soil salinity and flooding along an elevational gradient. Population dynamics of seeds have been found to determine the spatial and temporal distribution of species along salinity gradients. The flora and relative density of species of zonal communities are significantly dependent upon the stress tolerance of species at different stages of development and the presence of transient or persistent seed banks. The occurrence of a seed bank is related to the salinity tolerance of species at the germination stage of development, a seeds ability to tolerate hypersaline conditions and flooding, and whether or not species are able to maintain a persistent seed bank until hypersaline conditions are alleviated.