Rebecca J Howard , Ph.D.
Biography
EDUCATION
Ph.D., Oceanography and Coastal Sciences, Louisiana State University
M.S., Wildlife Biology (Minor: Botany) University of Massachusetts, Amherst
B.S., Wildlife Biology (Minor: Botany), State University of New York--College of Environmental Science and Forestry
RESEARCH
Rebecca Howard directs a research program on wetland plant community dynamics, including the effects of stressors and disturbances on plant community structure and function. She also conducts research on seed bank ecology, wetland restoration ecology, and plant response to factors associated with climate change.
Her research program centers on plant community dynamics in coastal wetlands of the northern Gulf of Mexico and inland wetlands of the southeastern U.S. The major goals of Howard's research are to: (1) determine how wetland plants respond to physicochemical stressors and disturbance, (2) develop an understanding of how biotic and abiotic factors affect plant community structure and composition, and (3) determine the mechanisms responsible for spatial and temporal variation in plant communities. Specific studies have included determining the effects of increased flooding and salinity on the growth of common perennial marsh macrophytes in field and greenhouse experiments, detailing vegetation succession patterns and seed bank characteristics on exposed soils of a large freshwater reservoir, describing soil and plant community response to disturbance associated with oil and gas exploration, and identifying intraspecific variation in stress tolerance of wetland plant species with the goal of identifying plants for use in restoration projects. Howard's current projects include studying the influence of a hydrological restoration project in the Florida Everglades region on mangrove forest expansion into marsh habitat.
Professional Positions
Research Ecologist, USGS National Wetlands Research Center / Wetland and Aquatic Research Center (1995 – present)
Ecologist, USFWS National Wetlands Research Center (1984 – 1995)
Wildife Biologist, USFWS National Coastal Ecosystems Team (1982 - 1984)
Science and Products
Relation between Plant Community Structure and Function and the Effectiveness of Wetland Restoration Efforts
High rates of wetland loss continue to occur along the northern Gulf of Mexico coast, and this remains an issue of concern to resource managers.
Climate Change Effects on Coastal Marsh Foundation Species
Mangrove forests have migrated inland over the past few decades at many locations along the northern Gulf of Mexico coast. This expansion has been attributed to factors associated with climate change, such as increased salinity resulting from sea-level rise and longer intervals between winter freezes, which can kill cold-intolerant mangrove species.
Plant Community Dynamics in a Mangrove-to-Marsh Transition Zone
Mangroves will compete with salt marsh plants in transitional areas, and recent studies have documented the expansion of mangroves into marsh habitats. To better understand the plant community dynamics in this transition zone, USGS scientists are tracking vegeation changes over time in south Florida.
Mapping Phragmites australis live fractional cover in the lower Mississippi River Delta, Louisiana
In response to a co-occurring non-native scale infestation and Phragmites australis dieback in southeast Louisiana, normalized difference vegetation index (NDVI) satellite mapping was implemented to track P. australis condition in the lower Mississippi River Delta. While the NDVI mapping successfully documented relative condition changes,...
Rangoonwala, Amina; Howard, Rebecca J.; Ramsey III, Elijah W.
Soil surface elevation dynamics in a mangrove-to-marsh ecotone characterized by vegetation shifts
Mangrove forest encroachment into coastal marsh habitats has been described in subtropical regions worldwide in recent decades. To better understand how soil processes may influence vegetation change, we studied soil surface elevation change, accretion rates, and soil subsurface change across a coastal salinity gradient in Florida, USA, an area...
Howard, Rebecca J.; From, Andrew; Krauss, Ken W.; Andres, Kimberly D.; Cormier, Nicole; Allain, Larry K.; Savarese, Michael Plant community establishment in a coastal marsh restored using sediment additions
A goal of wetland restoration is the establishment of resilient plant communities that persist under a variety of environmental conditions. We investigated the role of intraspecific and interspecific variation on plant community establishment in a brackish marsh that had been restored by sediment addition. Plant growth, sediment accretion, and...
Howard, Rebecca; Rafferty, Patricia S.; Johnson, Darren J. Response of tidal marsh vegetation to pulsed increases in flooding and nitrogen
Worldwide, human activities have modified hydrology and nutrient loading regimes in coastal wetlands. Understanding the interplay between these drivers and subsequent response of wetland plant communities is essential to informing wetland management and restoration efforts. Recent restoration strategies in Louisiana proposes to use sediment...
McCoy, Meagan M; Sloey, Taylor M; Howard, Rebecca J.; Hester, Mark W. How mangrove and salt marsh seedlings respond to CO2 and drought
Under our current changing climate, plants and animals must respond to rising sea levels, altered precipitation patterns, and increasing air and water temperatures and concentrations of greenhouse gases, including atmospheric carbon dioxide (CO2). While some species may adapt to changing conditions, these factors have the potential to drive...
Howard, Rebecca J. Early growth interactions between a mangrove and an herbaceous salt marsh species are not affected by elevated CO2 or drought
Increasing atmospheric carbon dioxide (CO2) concentrations are likely to influence future distributions of plants and plant community structure in many regions of the world through effects on photosynthetic rates. In recent decades the encroachment of woody mangrove species into herbaceous marshes has been documented along the U.S. northern Gulf...
Howard, Rebecca J.; Stagg, Camille L.; Utomo, Herry S. Linear and nonlinear effects of temperature and precipitation on ecosystem properties in tidal saline wetlands
Climate greatly influences the structure and functioning of tidal saline wetland ecosystems. However, there is a need to better quantify the effects of climatic drivers on ecosystem properties, particularly near climate-sensitive ecological transition zones. Here, we used climate- and literature-derived ecological data from tidal saline wetlands...
Feher, Laura C.; Osland, Michael J.; Griffith, Kereen T.; Grace, James B.; Howard, Rebecca J.; Stagg, Camille L.; Enwright, Nicholas M.; Krauss, Ken W.; Gabler, Christopher A.; Day, Richard H.; Rogers, Kerrylee Assessing coastal wetland vulnerability to sea-level rise along the northern Gulf of Mexico coast: Gaps and opportunities for developing a coordinated regional sampling network
Coastal wetland responses to sea-level rise are greatly influenced by biogeomorphic processes that affect wetland surface elevation. Small changes in elevation relative to sea level can lead to comparatively large changes in ecosystem structure, function, and stability. The surface elevation table-marker horizon (SET-MH) approach is being used...
Osland, Michael J.; Griffith, Kereen T.; Larriviere, Jack C.; Feher, Laura C.; Cahoon, Donald R.; Enwright, Nicholas M.; Oster, David A.; Tirpak, John M.; Woodrey, Mark S.; Collini, Renee C.; Baustian, Joseph J.; Breithaupt, Joshua L.; Cherry, Julia A; Conrad, Jeremy R.; Cormier, Nicole; Coronado-Molina, Carlos A.; Donoghue, Joseph F.; Graham, Sean A.; Harper, Jennifer W.; Hester, Mark W.; Howard, Rebecca J.; Krauss, Ken W.; Kroes, Daniel; Lane, Robert R.; McKee, Karen L.; Mendelssohn, Irving A.; Middleton, Beth A.; Moon, Jena A.; Piazza, Sarai; Rankin, Nicole M.; Sklar, Fred H.; Steyer, Gregory D.; Swanson, Kathleen M.; Swarzenski, Christopher M.; Vervaeke, William; Willis, Jonathan M; Van Wilson, K. Climatic controls on the global distribution, abundance, and species richness of mangrove forests
Mangrove forests are highly productive tidal saline wetland ecosystems found along sheltered tropical and subtropical coasts. Ecologists have long assumed that climatic drivers (i.e., temperature and rainfall regimes) govern the global distribution, structure, and function of mangrove forests. However, data constraints have hindered the...
Osland, Michael J.; Feher, Laura C.; Griffith, Kereen; Cavanaugh, Kyle C.; Enwright, Nicholas M.; Day, Richard H.; Stagg, Camille L.; Krauss, Ken W.; Howard, Rebecca J.; Grace, James B.; Rogers, Kerrylee Hydrologic restoration in a dynamic subtropical mangrove-to-marsh ecotone
Extensive hydrologic modifications in coastal regions across the world have occurred to support infrastructure development, altering the function of many coastal wetlands. Wetland restoration success is dependent on the existence of hydrologic regimes that support development of appropriate soils and the growth and persistence of wetland...
Howard, Rebecca J.; Day, Richard H.; Krauss, Ken W.; From, Andrew S.; Allain, Larry K.; Cormier, Nicole Growth of common brackish marsh macrophytes under altered hydrology and salinity regimes
Coastal marsh plants are increasingly subject to physicochemical stressors under rising sea levels, and the maintenance of marsh ecological functions can depend on the ability of individual species and communities to tolerate or adapt to altered conditions. We conducted a greenhouse experiment to identify hydrology and salinity effects on growth...
Howard, Rebecca J.; Biagas, Janelda M.; Allain, Larry K. Response of Schoenoplectus acutus and Schoenoplectus californicus at different life-history stages to hydrologic regime
For wetland restoration success to be maximized, restoration managers need better information regarding how the frequency, depth, and duration of flooding affect soil chemistry and the survival, growth, and morphology of targeted plant species. In a greenhouse study we investigated the impact of four different flooding durations (0 %, 40...
Sloey, Taylor M; Howard, Rebecca J.; Hester, Mark W.