Wetland seed bank response to sedimentation varying in loading rate and texture

Abstract

This study examined effects of two sediment textures applied in two loading rates on seedling recruitment from the seed bank in a wetland. Total seedling density (TSD) of an unsedimented, control treatment was 6.8-fold higher than the average density in sedimented treatments (2,085±971 seedlings m−2 versus 305±80 seedlings m−2). Consequently, biomass in the control, was significantly greater than biomass among sedimented treatments (84.4±29.5 gm m−2 versus 24.6±8.9 gm m2). Large sediment loads also significantly decreased TSD compared to low sediment loads (192±72 seedlings m−2 versus 417±87 seedlings m−2). Sediment texture did not significantly alter seedling density, but TSD was markedly suppressed by coarse-texture sediment relative to fine-texture sediment (258±67 seedlings m−2 versus 351±92 seedlings m−2). In addition, seedling density was significantly and positively correlated with seed mass in the coarsetextured treatments and in the low-loading treatments. The response to sedimentation by individual plant taxa was not consistent and presumably varied as a function of life-history characteristics. Species richness and diversity were significantly greater under the low loading treatment than the high loading treatment.