Grantee Research Project Results
Elucidating Patterns of Biomass Allocation in Panicum hemitomon: Implications for Floating Marsh Creation and RestorationEPA Grant Number: F5E11128
Title: Elucidating Patterns of Biomass Allocation in Panicum hemitomon: Implications for Floating Marsh Creation and Restoration
Investigators: Mayence, Charles E.
Institution: University of New Orleans
EPA Project Officer: Lee, Sonja
Project Period: September 1, 2005 through June 1, 2008
Project Amount: $104,450
RFA: STAR Graduate Fellowships (2005) RFA Text | Recipients Lists
Research Category: Academic Fellowships
The overarching goal of this study is to assess the feasibility of restoring large areas of thick-mat floating marsh. Thick-mat floating marsh is widely distributed throughout freshwater areas of coastal Louisiana and, like most wetlands, is important for nutrient retention, flood mitigation, and essential wildlife habitat. This study represents a first attempt at creating and restoring thick-mat floating marsh. Despite being well described, significant data gaps exist in the scientific literature regarding maidencane (Panicum hemitomon), the dominant macrophyte in floating marsh and the focal species of this study. For this project to be successful, as well as future floating marsh restoration efforts, a better working understanding of patterns of biomass allocation in P. hemitomon must be achieved. Elucidating specific plant growth responses (i.e., aerenchyma formation and root specific gravity, photosynthetic nutrient use efficiency, and root/shoot ratio) to differing environmental conditions (i.e., nutrient loading rate and flooding depth) are key objectives with direct ties to restoration. Furthermore, identifying environmental conditions that promote low specific gravity root tissue, while not compromising aboveground photosynthetic components, represents a formidable task, but one that must also be achieved. Much like assessing plant growth response variables in relation to differing environmental conditions, research must be done to elucidate the effects of different mat and substrate materials on P. hemitomon growth characteristics. Ultimately, these findings, along with those stemming from an analysis of multi-species plantings, will be incorporated into an optimized mat design and evaluated in a field setting.
This study combines multiple greenhouse and controlled setting (outdoor) experiments for the purpose of better understanding growth characteristics of P. hemitomon. The approach taken here is to first document the effects of differing environmental conditions on biomass allocation patterns and second, to apply these findings initially in simulated wetland habitats and then in a natural setting where floating marsh has been lost. P. hemitomon is a fast growing hydrophyte that primarily spreads via vegetative reproduction. This adaptation allows for rapid colonization of unoccupied space, making it ideal for vegetative mat creation. Oligotrophic, as opposed to eutrophic conditions, should promote aerenchyma formation while not negatively affecting root/shoot ratios. A moderate level of flooding (10 cm), in conjunction with reduced (hypoxic) soil conditions, should simultaneously result in stem elongation and aerenchyma formation. Based on preliminary data, peat-based substrates appear to be most favorable for plant growth. I feel confident in saying that results generated throughout this study will significantly advance creation and restoration efforts for thick-mat floating marsh, a much needed ecosystem in coastal Louisiana.