Methods

Twelve sediment cores were collected from the original full (200-ft. contour) waterline at each of 16 locations around Par Pond in 1994 before refilling. The sediment cores were returned to a “common garden area” on the Par Pond shoreline (Fig. 2a-b). There, cores were allocated to one of four water level treatments:

Fig. 2a-b. Experimental mesocosms at common garden area

1) moist soil (MS),
2) fluctuating at two (FLI) week intervals,
3) fluctuating at four (FLII) week intervals, or
4) continuously flooded (CF) at 10 cm depth, and one of three water source treatments (Table 1) with water taken from:  1)Par Pond (P), 2)Pond B (B), or 3) Savannah River (S).

To determine the additional contribution of propagules that might move up with the rising water, five soil cores were collected on a transect from the full water line down to the lowered waterline. These cores were flooded to simulate the effects of rising water. The floodwater was collected, pooled for all cores on a transect, and allocated equally among the water level treatments.                

Expression of both germination and growth effects on the plant community were observed for one growing season. In each container, cover was estimated by species to the nearest 1%; individuals were identified, clipped at the root-shoot junction, and dried at 68 degrees C to determine shoot biomass. Efforts to separate roots and rhizomes of individuals were not successful, and underground biomass was not determined.