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Rebecca J Howard , Ph.D.

Rebecca Howard is a Scientist Emeritus at the USGS Wetland and Aquatic Research Center. 

Rebecca Howard directed a research program on wetland plant community dynamics, including the effects of stressors and disturbances on plant community structure and function. She also conducted research on seed bank ecology, wetland restoration ecology, and plant response to factors associated with climate change. 

Her research program centered 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 were 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.

Professional Experience

  • Research Ecologist, USGS National Wetlands Research Center / Wetland and Aquatic Research Center (1995 – 2020)

    Ecologist, USFWS National Wetlands Research Center (1984 – 1995)

    Wildife Biologist, USFWS National Coastal Ecosystems Team (1982 - 1984)

     

Education and Certifications

  • 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),&nbs

Science and Products

Filter Total Items: 36

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, identification of cause required a quantitative-biophysical
By
Ecosystems, Wetland and Aquatic Research Center

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 with documented mangrove encroachment into saline mar
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Ecosystems, Climate Research and Development Program, Wetland and Aquatic Research Center

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 diversions from the Mississippi River to build land in ad
By
Ecosystems, Wetland and Aquatic Research Center

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 surface elevation change in planted, not-planted, and
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Ecosystems, Wetland and Aquatic Research Center

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 latitudinal and elevational shifts in species distributio
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Ecosystems, Wetland and Aquatic Research Center

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 of Mexico coast. These species shifts have been attr
By
Ecosystems, Wetland and Aquatic Research Center

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 to test hypotheses regarding the influence of climat
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Ecosystems, Wetland and Aquatic Research Center

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 globally to quantify the relative contributions of pro
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Ecosystems, Climate Research and Development Program, Land Change Science Program, Wetland and Aquatic Research Center

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 quantification of direct climate-mangrove linkages in many pa
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Ecosystems, Wetland and Aquatic Research Center

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 vegetation. In Florida, United States, the Comprehensive Eve
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Ecosystems, Wetland and Aquatic Research Center

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 of three common brackish marsh macrophytes of coasta
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Ecosystems, Wetland and Aquatic Research Center

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 %, 60 %, and 100 %) on soil physicochemistry and the respons
By
Ecosystems, Wetland and Aquatic Research Center
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A freshwater pond at Lacassine National Wildlife Refuge

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.
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Ecosystems, Land Management Research Program, Wetland and Aquatic Research Center
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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.
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Climate Change Effects on Coastal Marsh Foundation Species

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.
By
Ecosystems, Land Management Research Program, Wetland and Aquatic Research Center
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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.
Learn More
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Sampling permanent vegetation transects

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.
By
Ecosystems, Land Management Research Program, Wetland and Aquatic Research Center
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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.
Learn More

Phragmites australis live fractional cover yearly map from 2009 to 2019 of the lower Mississippi River Delta using Landsat and Sentinel-2 satellite data

Phragmites australis live fractional cover (LFC) maps were created of the lower Mississippi River Delta (MRD) using satellite image data. The historical 2009 to 2016 P. australis marsh LFC maps were based on yearly Landsat image data. The 2016 to 2019 P. australis marsh LFC maps were based on yearly Sentinel-2 image data.
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Wetland and Aquatic Research Center

Soil surface elevation dynamics in a mangrove-to-marsh ecotone characterized by vegetation shifts

This release consists of soil surface elevation, also called vertical land motion of the wetland (VLMw), and vertical accretion data collected over time across an environmental gradient at Ten Thousand Islands National Wildlife Refuge near Naples, Florida, USA. VLMw was measured using rod surface elevation tables, while accretion was measured using feldspar marker horizons (i.e., RSET-MH technique
By
Wetland and Aquatic Research Center

Plant community establishment in a coastal marsh restored using sediment additions, Barataria Basin, Louisiana

This data release consists of vegetation cover, soil surface elevation (also called vertical land motion of the wetland (VLMw)), and vertical accretion data collected over 23 months beginning in May 2001 in a restored brackish marsh in southeast Louisiana, USA. Vegetation cover was estimated in permanent plots, and soil cores were collected for determination of bulk density, organic matter content
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Wetland and Aquatic Research Center

Early growth interactions between a mangrove and an herbaceous salt marsh species are not affected by elevated CO2 or drought, Louisiana saltmarsh, 2015

In recent decades the encroachment of woody mangrove species into herbaceous marshes has been documented along the U.S. northern Gulf of Mexico coast. These species shifts have been attributed primarily to rising sea levels and warming winter temperatures, but the role of elevated atmospheric carbon dioxide (CO2) and water availability may become more prominent drivers of species interactions unde
By
Wetland and Aquatic Research Center

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

The study area included the coasts of all five U.S. states along the northern Gulf of Mexico (i.e., Florida, Alabama, Mississippi, Louisiana, and Texas). We contacted federal, state, and university-affiliated scientists working with SET-MH data within this area to obtain the geographic coordinates and the installation year for each SET-MH station. Please note that while our inventory is extensive
By
Wetland and Aquatic Research Center

Linear and nonlinear effects of temperature and precipitation on ecosystem properties in tidal saline wetlands

Macroclimatic drivers, such as temperature and rainfall regimes, greatly influence ecosystem structure and function in tidal saline wetlands. Understanding the ecological influence of macroclimatic drivers is important because it provides a foundation for anticipating the effects of climate change. Tidal saline wetlands include mangrove forests, salt marshes, and salt flats, which occupy similar g
By
Wetland and Aquatic Research Center
Phragmites under stress in Pass A Loutre, Louisiana
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Science and Products