Patterns of resource allocation in a coastal marsh plant (Schoenoplectus americanus) along a sediment-addition gradient
This data set includes hydro-edaphic and plant response data from a rhizotron experiment in which marsh sods were exposed to different levels of sedimentation. The study was designed to test the effects of sediment addition on plant growth and the mechanisms driving these responses along a sediment-addition gradient. We added sediment to Schoenoplectus americanus-dominated marsh sods in a greenhouse setting, achieving a sediment addition gradient (0 to 20 cm) across 18 experimental sods. These sods were placed in clear planting enclosures, or rhizotrons, to permit monitoring of above- and below-ground responses and hydro-edaphic conditions. We found that shoot production increased linearly along the sediment addition gradient, but that survival of those shoots declined with increasing sediment depth. After 6 months, shoot biomass production was biphasic, responding favorably to sediment addition up to intermediate depths before collapsing at greater depths. We also found that fine root production in the original rhizosphere was greatest at intermediate sediment addition levels, but root production in new sediment layers was limited. These differences in plant responses were detected despite limited differences in hydro-edaphic properties along the sediment addition gradient.