Effects of water level on the establishment and growth of Sparganium erectum

Abstract

Habitat environmental conditions for identifying the adult niche of Sparganium erectum were investigated in a field survey. The effect of water level on germination, establishment and growth of S. erectum seedlings was evaluated to identify the early life cycle in mesocosm experiments. In a field survey, the height and coverage of population B (living in deeper water) were greater than those of population A (living in shallow water). Means of water and soil environmental properties were not significant at p ≤ 0.05 between the two populations. In mesocosm experiments, I found no correlation between water levels and germination rates, but S. erectum seedlings have characteristics of post germination seedling buoyancy when germinated in inundation conditions. Shoot height, total leaf length and survival rates of sinking seedlings in shallow water levels at -5, 0, and 5 cm were higher than those in deeper water levels at 10 and 20 cm. Floating seedlings established in water levels of 3 and 6 cm only. The seedlings could live up to six weeks but died if they were unable to establish. I concluded that the water level around adult S. erectum populations in the field were different from the water level at which S. erectum seedlings can survive in the mesocosm experiments. The findings provided not only understanding of S. erectum habitat characteristics but also evidence to connect historical links between the early seedlings stage and adult habitat conditions.