Geology topics

Rebecca J. Howard

Publications and source records attributed to Rebecca J. Howard.

27 records · Page 2Linked to original sources

USGS2007

Vegetation Response to the 1995 Drawdown of the Navigation Pool at Felsenthal National Wildlife Refuge, Crossett, Arkansas

Felsenthal Navigation Pool (?the pool?) at Felsenthal National Wildlife Refuge near Crossett, Ark., was continuously flooded to a baseline elevation of 19.8 m (65.0 ft) mean sea level (m.s.l.) from late fall 1985, when the final in a series of locks and dams was constructed, until the summer of 1995. Water level within the pool was reduced by 0.3 m (1.0 ft) beginning July 5, 1995, exposing about 1,591 ha (3,931 acres) of sediment; the reduced water level was maintained until October 25 of that year. A total of 15 transects was established along the pool margin before the drawdown, extending perpendicular from the pool edge to 19.5 m (64.0 ft) in elevation. Plant species composition and cover were recorded at six to seven quadrats on each transect; 14 of the transects were also monitored three times during the drawdown and in June 1996. Soil near five of the original transects was disturbed two weeks into the drawdown by scraping the soil surface with a bulldozer. Soil cores were collected to characterize soil organic matter, texture class, carbon and nitrogen content, and plant nutrient concentrations; soil samples were also collected to identify species present in the seed bank prior to and during the drawdown. Plant species, several of which were high quality food sources for waterfowl, colonized the drawdown zone within four weeks. Vegetation response, measured by species richness, total cover, and cover of Cyperus species, was often greater at low compared to high elevations in the drawdown zone; this effect was probably intensified by low rainfall during the summer of 1995. Vegetation response on the disturbed transects was reduced compared to that on the undisturbed transects. This effect was attributed to two factors: (1) removal of the existing seed bank by the disturbance technique applied and (2) reduced incorporation of seeds recruited during the drawdown because of unusually low summer rainfall. Seed bank studies demonstrated that several species persisted despite nearly 10 years of continual flooding, and that seed bank species richness increased during the drawdown. Analyses indicated that predominantly clay soils containing relatively low organic matter were present along the pool margin. Levels of the plant nutrients measured were consistent with normal values reported for soils. Although conclusions from this study are limited by its one-year time frame, it is unlikely that permanent change to plant community function in the drawdown zone resulted from the lowered water levels during the summer of 1995. While species composition in the summer following the drawdown differed from that prior to the drawdown, the plant community remained dominated by annual floating-leaved or submersed species. It is probable that any future decrease in summer water levels in the pool will result in increased growth of desirable waterfowl food plants, such as Cyperus erythrorhizos (red-root flat sedge) and Leptochloa fascicularis var. fascicularis (bearded sprangletop), in the drawdown zone.

Open-File Report↗

USGS2003

Native plants for effective coastal wetland restoration

Plant communities, along with soils and appropriate water regimes, are essential components of healthy wetland systems. In Louisiana, the loss of wetland habitat continues to be an issue of major concern. Wetland loss is caused by several interacting factors, both natural and human-induced (e.g., erosion and saltwater intrusion from the construction of canals and levees). Recent estimates of annual coastal land loss rates of about 62 km2 (24 mi2 ) over the past decade emphasize the magnitude of this problem. In an attempt to slow the rate of loss and perhaps halt the overall trend, resource managers in Louisiana apply various techniques to restore damaged or degraded habitats to functioning wetland systems. Researchers at the U.S. Geological Survey’s National Wetlands Research Center (NWRC) have cooperated with the Louisiana Department of Natural Resources in studies that address effective restoration strategies for coastal wetlands. The studies have identified differences in growth that naturally exist in native Louisiana wetland plant species and genetic varieties (i.e., clones) within species. Clones of a species have a distinctive genetic identity, and some clones may also have distinctive growth responses under various environmental conditions (i.e., preferences). Indeed, large areas of coastal marsh are typically populated by several clones of a plant species, each growing in a microenvironment suited to its preferences. These studies will provide information that will assist resource managers in selecting plant species and clones of species with known growth characteristics that can be matched to environmental conditions at potential restoration sites. Before the studies began, a collection of several clones from four plant species native to coastal Louisiana was established. The species collected included saltgrass (Distichlis spicata), common reed (Phragmites australis), giant bulrush (Schoenoplectus californicus), and saltmarsh bulrush (Schoenoplectus robustus). Plants connected by roots were collected from public lands across the coastal zone, and then allowed to grow several months and produce new stems and plants from underground stems called “rhizomes.” These procedures maintained the genetic identity of the clones and allowed the plants to adjust to greenhouse conditions before experimental treatments began.

Fact Sheet↗

USGS1995

Effect of increased water depth on growth of a common perennial freshwater-intermediate marsh species in Coastal Louisiana

The response of Sagittaria lancifolia to increased water depths of 7.5 and 15 cm was examined in this field study. Water-depth treatments were achieved by digging sods containing one or two individual plants or ramets of S. lancifolia from the marsh, removing sediment from the resulting hole, and replacing the sods in their original location at the appropriate lower elevation. Plants subjected to increased water depth of 15 cm had higher mean and maximum leaf heights than disturbed control plants. Aboveground biomass was not affected by water-depth treatment; however, 15-cm treatment plants had reduced root biomass and lowered leaf tissue concentrations of Ca, Cu, Fe, Mg, and Zn. Marsh sods at 15 cm below the marsh surface had the lowest redox potential and highest interstitial water sulfide concentration, indicating that this treatment created the most stressful belowground environment. Sagittaria lancifolia plants responded to the level of stress imposed by the experimental conditions with an altered growth form of increased leaf height.

Louisiana↗

USGS1989

Streamside habitats in southern forested wetlands: Their role and implications for management

The value of streamside forests to fish and wildlife and the influence of forest management on their value have been recognized in a general sense for decades. However, in today’s climate of increasing environmental regulation and intensive forest management, there is need for more detailed understanding of the value of streamside forests to fish and wildlife. Dickson and Huntley (1987:38) described the problem well when they wrote that “quantitative data on the effects of riparian zones on wildlife populations are insufficient to enable wildlife managers to justify the retention of riparian zones in land-use plans on a biological and economical basis.” Due in large part to the passage of water pollution control legislation, as well as legislation mandating multiple-use management in our national forests, progress is being made. During the last l&15 years, a great deal of research has been directed at understanding the value and appropriate management of the riparian zone (Brouha and Parsons 1985). The vast majority of research on riparian habitats has been conducted in western forests and/or narrow zones in otherwise upland areas. Also, much of the work done in southern forested wetlands has applied to entire floodplain forests. In this paper, we review the literature on streamside habitats within southern forested wetlands and, for reasons described in the next section, we make a distinction between streamside forests and floodplain (or riparian) forests. We also discuss in less detail the value of streamside habitats within other southern forest types, such as pine or mixed pine-hardwood.

General Technical Report↗

USGS1987

Habitat Suitability Index Models: Black-shouldered kite

A review and synthesis of existing information were used to develop a model for evaluating black-shouldered kite habitat quality. The model is scaled to produce an index between 0 (unsuitable habitat) to 1.0 (optimal habitat). Habitat suitability index models are designed for use with the Habitat Evaluation Procedures previously developed by the U.S. Fish and Wildlife Service. Guidelines for model application are provided.

FWS/OBS↗

USGS1987

Habitat Suitability Index Models: American alligator

A review and synthesis of existing information were used to develop a model for evaluating American alligator habitat quality. The model is applicable in marshes along the northern Gulf of Mexico. It is scaled to produce an index between 0 (unsuitable habitat) and 1.0 (optimal habitat). Habitat suitability index models are designed for use with the Habitat Evaluation Procedures previously developed by the U.S. Fish and Wildlife Service. Guidelines for model application and techniques for measuring model variables are described.

FWS/OBS↗

USGS1986

Habitat Suitability Index Models: Northern pintail (gulf coast wintering)

A review and synthesis of existing information were used to develop a model for evaluating wintering habitat quality for northern pintail (Anas acuta) along the Gulf of Mexico coast. The model is scaled to produce an index between unsuitable habitat) and 1.0 (optimal habitat). Habitat suitability index models are designed for use with the Habitat Evaluation Procedures previously developed by the U.S. Fish and Wildlife Service. Guidelines for model application and techniques for measuring model variables are provided.

FWS/OBS↗

USGS1984

Habitat Suitability Index Models: Great egret

The great egret, also called common egret or American egret, is a large white heron tn the order Ciconiiformes, family Ardeidae. Great egrets stand 94.0-104.1 cm (37-41 inches) tall and have a wing spread to 139.7 cm (55 inches) (Terres 1980). The species is associated with streams, ponds, lakes, mud flats, swamps, ahd freshwater and salt marshes. The birds feed in shallow water on fishes, amphibians, reptiles, crustaceans and insects (Terres 1980).

FWS/OBS↗

USGS1983

Habitat suitability index models: redhead (wintering)

The redhead is a North American waterfowl species with economic as well as ecological importance. It is highly desired by hunters. Retrieved redhead kill in the United States averaged 143,000 birds during the three waterfowl seasons from 1975 to 1977 (U.S. Department of the Interior 1981a, 1981b). Populations on the principal breeding grounds of the redhead--the prairie and parkland region of south-central Canada and north-central United States--averaged 710,000 birds from 1955 to 1981 (Bellrose 1976; A. Novara, U.S. Fish and Wildlife Service [USFWS], Jamestown, North Dakota; pers. comm.). Redhead numbers began to decline in the 1960's. Killing redheads became illegal from 1960 to 1963, and strict bag limits were imposed after that (Bellrose 1976). A breeding population low of 387,000 birds occurred in 1963, but prairie populations began to recover after that time. Their numbers peaked in 1980 when 1,146,000 birds were recorded (A. Novara, pers. comm.). During the fall, over a third of the total redhead population uses the migration corridor that extends from the prairie breeding area to the Texas gulf coast. Another migration corridor extends from the second most important breeding area--the Great Salt Basin--to the Texas coast (Bellrose 1976). During the fall, over a third of the total redhead population uses the migration corridor that extends from the prairie breeding area to the Texas gulf coast. Another migration corridor extends from the second most important breeding area--the Great Salt Basin--to the Texas coast (Bellrose 1976).

FWS/OBS↗