Assessment of growth response and patterns of biomass allocation by Panicum hemitomon Schultes: Implications for thick-mat floating marsh creation and restoration.

摘要

I carried out several large, manipulative greenhouse and controlled-setting experiments to elucidate Panicum hemitomon growth response as influenced by environmental conditions associated with restoring thick-mat floating marsh. Initially, Panicum hemitomon growth response was assessed in conjunction with manipulated nutrient availability and hydrology. Next, I assessed Panicum hemitomon growth response in conjunction with a suite of substrate and mat or containment materials. Finally, I evaluated Panicum hemitomon growth response, as well as overall created floating marsh vegetated development, using both a multi-species planting approach and a suite of Panicum hemitomon establishment techniques.;This research generated data that not only advance the body of general ecological knowledge pertaining to Panicum hemitomon, the dominant macrophyte of thick-mat floating marsh, but equally as important, data that are likely to augment or enhance the creation and restoration of this important freshwater marsh type.;Keywords. Panicum hemitomon, floating marsh, biomass allocation, multi-species approach.;All partitions of Panicum hemitomon biomass (shoot, rhizome, and root material) were enhanced under nitrogen, and to a lesser extent, phosphorous enrichment. Saturated (not inundated) hydrologic conditions were most conducive for robust growth by all partitions of Panicum hemitomon biomass. Substrate and mat or containment materials had a significant effect on Panicum hemitomon vigor, with peat and peat-containing blended substrate materials being most conducive for vigorous Panicum hemitomon growth. Duralast coconut fiber was the most suitable mat or containment material based not only on measures of plant vigor, but also for reasons associated with strength and stability, as well as buoyancy. The combination of Panicum hemitomon and Ludwigia peploides was superior to any other multi-species treatment tested. Ludwigia peploides was highly resilient to transplanting, grew vigorously in a lateral fashion, produced significantly more biomass than any other secondary species, and enhanced overall mat buoyancy, all key metrics regarding successful floating marsh restoration. Equally as important, the large amount of biomass attained by Ludwigia peploides was not totally at the expense of vigorous Panicum hemitomon growth. With respect to establishment technique, the positive response of Panicum hemitomon rhizome growth to humic acid amendment warrants further study.