Effects of water level and phosphorus enrichment on seedling emergence from marsh seed banks collected from northern Belize

The effects of water level and nutrient additions on seed germination from the seed banks of phosphorus-limited freshwater herbaceous wetlands in Northern Belize, Central America, were tested in a greenhouse study. Seed bank soil was exposed to both draw-down and flooded conditions with and without added phosphorus (P) in a replicated germination assay. The seed banks of herbaceous species, as assessed by seedling emergence, in 7 marshes of the study area ranged in size from 55 to 1556 seeds m(-2) and from 4 to 15 species. The dominant species in the standing vegetation, Typha domingensis Pers., Eleocharis cellulosa Torr., and Cladium jamaicense Crantz, were almost completely absent in the seed banks. The addition of phosphorus and flooding each reduced the number of species germinating from the seed banks by 50%, although the effect of water level varied by marsh. Phosphorus had a greater effect on the total number of seedlings emerging in flooded than draw-down treatments, reducing emergence by 75 and 20%, respectively. Overall, flooding reduced seedling emergence by 50%. The emergence of Typha from the seed banks, a competitive dominant in the marshes, was not increased by the addition of P. (C) 2004 Elsevier B.V. All rights reserved.