Rebecca J Howard, Ph.D.
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
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.
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
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.
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.
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.
Plant-plant interactions in a subtropical mangrove-to-marsh transition zone: effects of environmental drivers
Questions Does the presence of herbaceous vegetation affect the establishment success of mangrove tree species in the transition zone between subtropical coastal mangrove forests and marshes? How do plant–plant interactions in this transition zone respond to variation in two primary coastal environmental drivers? Location Subtropical...Howard, Rebecca J.; Krauss, Ken W.; Cormier, Nicole; Day, Richard H.; Biagas, Janelda M.; Allain, Larry K.
Effects of disturbance associated with seismic exploration for oil and gas reserves in coastal marshes
Anthropogenic disturbances in wetland ecosystems can alter the composition and structure of plant assemblages and affect system functions. Extensive oil and gas extraction has occurred in wetland habitats along the northern Gulf of Mexico coast since the early 1900s. Activities involved with three-dimensional (3D) seismic exploration for these...Howard, Rebecca J.; Wells, Christopher J.; Michot, Thomas C.; Johnson, Darren J.
Phragmites australis expansion in a restored brackish marsh: documentation at different time scales
Invasive plants in restored habitats can alter the system such that restoration goals are not met. Non-native lineages of Phragmites australis (hereafter Phragmites) are invasive in North American wetlands, and their presence can be problematic because of decreased species diversity and altered physicochemical processes. Phragmites is a...Howard, Rebecca J.; Turluck, Theodore D.
Effects of a drawdown on plant communities in a freshwater impoundment at Lacassine National Wildlife Refuge, Louisiana
Disturbance is an important natural process in the creation and maintenance of wetlands. Water depth manipulation and prescribed fire are two types of disturbance commonly used by humans to influence vegetation succession and composition in wetlands with the intention of improving wildlife habitat value. A 6,475-hectare (ha) impoundment was...Howard, Rebecca J.; Allain, Larry
On the relative roles of hydrology, salinity, temperature, and root productivity in controlling soil respiration from coastal swamps (freshwater)
Background and aims Soil CO2 emissions can dominate gaseous carbon losses from forested wetlands (swamps), especially those positioned in coastal environments. Understanding the varied roles of hydroperiod, salinity, temperature, and root productivity on soil respiration is important in discerning how carbon balances may shift as freshwater swamps...Krauss, Ken W.; Whitbeck, Julie L.; Howard, Rebecca J.