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William R. Jones

Publications and source records attributed to William R. Jones.

11 recordsLinked to original sources
USGS2019

Quantifying hydrologic controls on local- and landscape-scale indicators of coastal wetland loss

Background and Aims Coastal wetlands have evolved to withstand stressful abiotic conditions through the maintenance of hydrologic feedbacks among vegetation production and flooding. However, disruption of these feedbacks can lead to ecosystem collapse, or a regime shift from vegetated wetland to open water. To prevent the loss of critical coastal wetland habitat, we must improve understanding of the abiotic-biotic linkages among flooding and wetland stability. The aim of this research was to identify characteristic landscape patterns and thresholds of wetland degradation that can be used to identify areas of vulnerability, reduce flooding threats, and improve habitat quality. Methods We measured local- and landscape-scale responses of coastal wetland vegetation to flooding stress in healthy and degrading coastal wetlands. We hypothesized that conversion of Spartina patens wetlands to open water could be defined by a distinct change in landscape configuration pattern, and that this change would occur at a discrete elevation threshold. Key Results Despite similarities in total land and water cover, we observed differences in the landscape configuration of vegetated and open water pixels in healthy and degrading wetlands. Healthy wetlands were more aggregated, and degrading wetlands were more fragmented. Generally, greater aggregation was associated with higher wetland elevation and better drainage, compared to fragmented wetlands, which had lower elevation and poor drainage. The relationship between vegetation cover and elevation was non-linear, and the conversion from vegetated wetland to open water occurred beyond an elevation threshold of hydrologic stress. Conclusions The elevation threshold defined a transition zone where healthy, aggregated, wetland converted to a degrading, fragmented, wetland beyond an elevation threshold of 0.09 m NAVD88 (0.27 m MSL), and complete conversion to open water occurred beyond 0.03 m NAVD88 (0.21 m MSL). This work illustrates that changes in landscape configuration can be used as an indicator of wetland loss, with specific elevation thresholds to inform restoration and conservation planning to maximize wetland stability in anticipation of flooding threats.

Louisiana, Texas↗
USGS2019

Using UAS capabilities to help identify hummock-hollow formation and fragmentation in critical marsh habitat ( Spartina patens ) for mottled ducks in southeast Texas

For many years, marshes in the coastal areas from Texas to Louisiana have served as critical habitat for Anas fulvigula , the mottled duck. Mottled ducks are a priority species in the Texas/Louisiana Gulf Coast area and have been affected by critical habitat reduction. In recent years, mottled duck habitats have been threatened by natural and anthropogenic changes including urbanization, flooding, saltwater intrusion, and hydrologic alterations. These impacts are affecting the quality of habitat that is essential for the mottled duck nesting, feeding, and livelihood. Cumulative and synergistic effects of contamination and invasive species encroachment have also caused mottled duck habitat to be considered as some of the most critically endangered habitats in the United States. To help understand the environmental conditions that characterize the coastal landscape, U.S. Geological Survey researchers used an unmanned aerial system (UAS) to acquire high-resolution imagery to document current land and water spatial configuration and wetland health at McFaddin National Wildlife Refuge, Texas.

Texas↗
USGS2018

Barataria and Terrebonne Bays: Chapter F in Emergent wetlands status and trends in the northern Gulf of Mexico: 1950-2010

The study area included in the Barataria and Terrebonne Bays vignette of southeastern Louisiana spans eastward from Terrebonne Bay to Barataria Bay (Figure 1) and includes portions of Terrebonne, Lafourche, St. Charles, Jefferson, Orleans, Plaquemines, and St. Bernard Parishes. This area falls between the Mississippi River on the east and northeast, extends down through the western shore of Lake Salvador and the Dixie Delta Canal, then runs west to Houma and follows Louisiana Route 315 to the coast; Barataria and Terrebonne Bays are separated from each other by Bayou Lafourche.

Louisiana↗
USGS2018

Mississippi Delta: Chapter G in Emergent wetlands status and trends in the northern Gulf of Mexico: 1950-2010

The Mississippi River Delta, the tip of the longest river in North America, is located in the coastal plains of southeastern Louisiana. The study area included in the Mississippi River Delta vignette of southeastern Louisiana follows the Mississippi River southward from Port Sulphur within the modern Plaquemines-Balize Delta lobe (Figure 1). It extends eastward through Long Bay into California Bay and then encapsulates most of the land to the east of the river; it extends south into Lake Washington and Lake Robinson, then to the Gulf of Mexico, and includes the land to the west of the river. All of this area is within Plaquemines Parish. The mouth of the Mississippi includes four subdeltas (West Bay, Cubit’s Gap, Baptiste Collette, and Garden Island Bay) which began formation between 1839 and 1891 (Coleman and others, 1998). As of 2010, the total land area from Venice, LA to the gulf was 357.50 square km (138.03 square miles) and had ranged from 208.08 square km (80.34 square miles) to 393.70 square km (152.01 square miles) since 1973 (Couvillion and others, 2011).

Louisiana↗
USGS2016

Mangrove expansion and contraction at a poleward range limit: Climate extremes and land-ocean temperature gradients

Within the context of climate change, there is a pressing need to better understand the ecological implications of changes in the frequency and intensity of climate extremes. Along subtropical coasts, less frequent and warmer freeze events are expected to permit freeze-sensitive mangrove forests to expand poleward and displace freeze-tolerant salt marshes. Here, our aim was to better understand the drivers of poleward mangrove migration by quantifying spatiotemporal patterns in mangrove range expansion and contraction across land-ocean temperature gradients. Our work was conducted in a freeze-sensitive mangrove-marsh transition zone that spans a land-ocean temperature gradient in one of the world's most wetland-rich regions (Mississippi River Deltaic Plain; Louisiana, USA). We used historical air temperature data (1893-2014), alternative future climate scenarios, and coastal wetland coverage data (1978-2011) to investigate spatiotemporal fluctuations and climate-wetland linkages. Our analyses indicate that changes in mangrove coverage have been controlled primarily by extreme freeze events (i.e., air temperatures below a threshold zone of -6.3 to -7.6 °C). We expect that in the past 121 years, mangrove range expansion and contraction has occurred across land-ocean temperature gradients. Mangrove resistance, resilience, and dominance were all highest in areas closer to the ocean where temperature extremes were buffered by large expanses of water and saturated soil. Under climate change, these areas will likely serve as local hotspots for mangrove dispersal, growth, range expansion, and displacement of salt marsh. Collectively, our results show that the frequency and intensity of freeze events across land-ocean temperature gradients greatly influences spatiotemporal patterns of range expansion and contraction of freeze-sensitive mangroves. We expect that, along subtropical coasts, similar processes govern the distribution and abundance of other freeze-sensitive organisms. In broad terms, our findings can be used to better understand and anticipate the ecological effects of changing winter climate extremes, especially within the transition zone between tropical and temperate climates.

Louisiana↗
USGS2014

Analysis of the impact of spatial resolution on land/water classifications using high-resolution aerial imagery

Long-term monitoring efforts often use remote sensing to track trends in habitat or landscape conditions over time. To most appropriately compare observations over time, long-term monitoring efforts strive for consistency in methods. Thus, advances and changes in technology over time can present a challenge. For instance, modern camera technology has led to an increasing availability of very high-resolution imagery (i.e. submetre and metre) and a shift from analogue to digital photography. While numerous studies have shown that image resolution can impact the accuracy of classifications, most of these studies have focused on the impacts of comparing spatial resolution changes greater than 2 m. Thus, a knowledge gap exists on the impacts of minor changes in spatial resolution (i.e. submetre to about 1.5 m) in very high-resolution aerial imagery (i.e. 2 m resolution or less). This study compared the impact of spatial resolution on land/water classifications of an area dominated by coastal marsh vegetation in Louisiana, USA, using 1:12,000 scale colour-infrared analogue aerial photography (AAP) scanned at four different dot-per-inch resolutions simulating ground sample distances (GSDs) of 0.33, 0.54, 1, and 2 m. Analysis of the impact of spatial resolution on land/water classifications was conducted by exploring various spatial aspects of the classifications including density of waterbodies and frequency distributions in waterbody sizes. This study found that a small-magnitude change (1–1.5 m) in spatial resolution had little to no impact on the amount of water classified (i.e. percentage mapped was less than 1.5%), but had a significant impact on the mapping of very small waterbodies (i.e. waterbodies ≤ 250 m 2 ). These findings should interest those using temporal image classifications derived from very high-resolution aerial photography as a component of long-term monitoring programs.

Louisiana↗
USGS2014

Pictorial account and landscape evolution of the crevasses near Fort St. Philip, Louisiana

Quantifying the effects of active natural and constructed crevasses is critical to the planning and success of future ecosystem restoration activities. This document provides a historical overview of landscape changes within the vicinity of the natural crevasses near Fort St. Philip, Louisiana. A significant event influencing landscape change within the Fort St. Philip study area was the breaching of the eastern levee of the Mississippi River. Initially, the river water that was diverted through these crevasse channels physically removed significant marsh areas within the study area. These initial direct impacts were succeeded by several decades of larger regional loss patterns driven by subsidence and other episodic events (e.g, hurricanes and floods), and recent localized land gains. These increases in land area are potentially the long-term results of the Fort St. Philip crevasses, and the short-term impacts of delta management activities. However, for the majority of the 1956-2008 period of analysis, the crevassing of the eastern bank of the Mississippi River levee was a loss accelerant in the Fort St. Philip area.

Louisiana↗
USGS2013

Classifications for Coastal Wetlands Planning, Protection and Restoration Act (CWPPRA) site-specific projects: 2010

The Coastal Wetlands Planning, Protection and Restoration Act (CWPPRA) funds over 100 wetland restoration projects across Louisiana. Integral to the success of CWPPRA is its long-term monitoring program, which enables State and Federal agencies to determine the effectiveness of each restoration effort. One component of this monitoring program is the classification of high-resolution, color-infrared aerial photography at the U.S. Geological Survey’s National Wetlands Research Center in Lafayette, Louisiana. Color-infrared aerial photography (9- by 9-inch) is obtained before project construction and several times after construction. Each frame is scanned on a photogrametric scanner that produces a high-resolution image in Tagged Image File Format (TIFF). By using image-processing software, these TIFF files are then orthorectified and mosaicked to produce a seamless image of a project area and its associated reference area (a control site near the project that has common environmental features, such as marsh type, soil types, and water salinities.) The project and reference areas are then classified according to pixel value into two distinct classes, land and water. After initial land and water ratios have been established by using photography obtained before and after project construction, subsequent comparisons can be made over time to determine land-water change.

Louisiana↗
USGS2012

Classifications for Coastal Wetlands Planning, Protection and Restoration Act site-specific projects: 2008 and 2009

The Coastal Wetlands Planning, Protection and Restoration Act (CWPPRA) funds over 100 wetland restoration projects across Louisiana. Integral to the success of CWPPRA is its long-term monitoring program, which enables State and Federal agencies to determine the effectiveness of each restoration effort. One component of this monitoring program is the analysis of high-resolution, color-infrared aerial photography at the U.S. Geological Survey's National Wetlands Research Center in Lafayette, Louisiana. Color-infrared aerial photography (9- by 9-inch) is obtained before project construction and several times after construction. Each frame is scanned on a photogrametric scanner that produces a high-resolution image in Tagged Image File Format (TIFF). By using image-processing software, these TIFF files are then orthorectified and mosaicked to produce a seamless image of a project area and its associated reference area (a control site near the project that has common environmental features, such as marsh type, soil types, and water salinities.) The project and reference areas are then classified according to pixel value into two distinct classes, land and water. After initial land and water ratios have been established by using photography obtained before and after project construction, subsequent comparisons can be made over time to determine land-water change. Several challenges are associated with the land-water interpretation process. Primarily, land-water classifications are often complicated by the presence of floating aquatic vegetation that occurs throughout the freshwater systems of coastal Louisiana and that is sometimes difficult to differentiate from emergent marsh. Other challenges include tidal fluctuations and water movement from strong winds, which may result in flooding and inundation of emergent marsh during certain conditions. Compensating for these events is difficult but possible by using other sources of imagery to verify marsh conditions for other dates in time.

Louisiana↗
USGS2000

Northeastern Gulf of Mexico Coastal and Marine Ecosystem Program: Coastal Characterization: an overview and update

The U.S. Geological Surveys Biological Resources Division (BRD) mission is to provide leadership in gathering, analyzing, and disseminating biological information as support for sound management of the Nation's natural resources. Since becoming operational in October of 1996 through the transfer of programs from various bureaus within the Department of the Interior, the BRD, in cooperation with other Federal, State, and local partners, has begun research, inventory and monitoring, information sharing, and technology transfer. Through these activities, the BRD is fostering an understanding of biological systems and their benefits to society, and providing the essential scientific support and technical assistance required for management and policy decisions. The role of BRD' s National Wetlands Research Center (NWRC) in Lafayette, Louisiana, with project offices in Baton Rouge, LA and Gulf Breeze, FL, is to provide leadership in research and development related to the Nation's natural resources for the Southeast. The research focuses on wetlands ecology, animal ecology, and the development and application of spatial analysis techniques for natural resource related studies. Current geographic information system (GIS) technologies in use at NWRC are designed to provide natural resource managers with the on-line data and computerized techniques necessary to make informed decisions. Major GIS activities at NWRC include: compilation and analysis of digital databases for monitoring of natural resources; integration and transfer of databases with existing digital databases from various sources into a comprehensive GIS; and development of multifunctional decision support systems for natural resource managers using these data. NWRC is also an active participant in the National Information Infrastructure (NIT), in particular the National Spatial Data Infrastructure (NSDI) and the National Biological Information Infrastructure (NBTI), which will facilitate the dissemination of research results and other knowledge and information gained from these efforts. This summary and the three summaries that follow provides an overview and update of a four year study entitled, Northeastern Gulf of Mexico Coastal and Marine Ecosystem Program: Coastal Characterization.

Minerals Management Service↗