Grantee Research Project Results
2001 Progress Report: Regional Ecological Resource Assessment of the Rio Grande Riparian Corridor: A Multidisciplinary Approach to Understanding Anthropogenic Effects on Riparian Communities in Semi-arid Environments
EPA Grant Number: R827677Title: Regional Ecological Resource Assessment of the Rio Grande Riparian Corridor: A Multidisciplinary Approach to Understanding Anthropogenic Effects on Riparian Communities in Semi-arid Environments
Investigators: Raney, Jay , Neuenschwander, Amy , Judd, Frank , Paull, Gene , Crawford, Melba , Lonard, Robert , Tremblay, Thomas , White, William
Current Investigators: Raney, Jay , Crawford, Melba , Neuenschwander, Amy , Paull, Gene , Judd, Frank , Lonard, Robert , Tremblay, Thomas , White, William , Encheva, Tatiana
Institution: The University of Texas at Austin , The University of Texas at Brownsville , The University of Texas - Pan American
Current Institution: The University of Texas at Austin , The University of Texas - Pan American , The University of Texas at Brownsville
EPA Project Officer: Packard, Benjamin H
Project Period: September 1, 1999 through August 31, 2002 (Extended to December 31, 2003)
Project Period Covered by this Report: September 1, 2000 through August 31, 2001
Project Amount: $642,496
RFA: Regional Scale Analysis and Assessment (1999) RFA Text | Recipients Lists
Research Category: Aquatic Ecosystems , Ecological Indicators/Assessment/Restoration
Objective:
Riparian ecosystems of the southwestern United States are among the most productive ecosystems of North America. The rapid decline of these ecosystems throughout the United States has made riparian conservation a focal issue. This multidisciplinary, 3-year study of riparian communities along the Lower Rio Grande Valley of Texas and Mexico has several objectives, including: (1) acquiring and analyzing high-resolution, remotely sensed data from multiple sensors; (2) integrating existing and new field data and remotely sensed data into a geographic information system (GIS); (3) ascertaining whether the native vegetation communities are maintaining themselves and identifying the topographic, edaphic, and other ecological factors that perpetuate these communities; (4) interpreting spatial variations in riparian habitats, including comparisons of the north and south banks of the Rio Grande; (5) analyzing temporal changes at specific locations; and (6) developing a foundation for future analysis of riparian floodplain communities by linking local and remotely sensed regional data using GIS.Progress Summary:
Progress during the second year was made primarily in the areas of current land-use mapping, vegetation surveys, remote data classification, data acquisition, GIS development, and analysis/modeling in the GIS environment. Eight detailed local-scale ecological transects of dominant riparian vegetation were completed, seven of which were initially established and surveyed in the mid-1990s. In addition, more than 100 sites were examined in the field, the dominant vegetation at these sites was identified and recorded, and the results were entered into a GIS. On the basis of the vegetation composition and according to their evergreen and deciduous makeup, we classified all sites into five subclasses. This riparian classification is modeled after the U.S. Fish and Wildlife Service (USFWS) National Wetlands Inventory program, in which riparian vegetation inventory and mapping conventions were developed for the Western United States using a hierarchical classification.The local-scale vegetation transects and ground-truth sites are being correlated with high-resolution, remote-sensing data to delineate the spatial extent and composition of the riparian community. Classification output from high-resolution imagery in turn provides the class mixtures for medium-resolution (20- to 30-m), satellite multispectral data that cover the entire study area on both sides of the Rio Grande. Preliminary GIS analysis of riparian forests and shrubs along the Rio Grande, which was based on medium-resolution Landsat TM imagery, indicates that along a 3-km-wide corridor on the U.S. side of the river, only 6 percent of the area has riparian vegetation, whereas along a similar corridor in Mexico, only 2 percent is riparian. To gain a more quantitative understanding of historical distribution patterns of riparian vegetation and the location and magnitude of losses, we digitized and analyzed woodlands as depicted on USGS topographic maps prepared in the early 1900s (1916?1936). Results indicate that in the mid-1930s approximately 81,887 ha of woodlands could be found in Cameron County. By the early to mid-1980s, only 7,337 ha of woodlands in this original area remained, indicating a loss of approximately 91 percent of this resource. The limited amount of riparian vegetation supports estimates by Jahrsdoerfer and Leslie (1988) that 99 percent has been removed along the Rio Grande since the 1900s. Riparian vegetation studied along transects at eight field sites along the Rio Grande, however, suggests that the dominant trees and shrubs in existing riparian communities are replacing themselves. In addition, efforts by the USFWS, as part of the Lower Rio Grande Valley National Wildlife Refuge acquisition program, have been successful in reestablishing riparian vegetation in many areas. This program is ongoing.
One element of the methodology is to use the interpretative capabilities of a GIS to examine linkages between riparian ecology and parameters such as geology, topography, soils, water quality, hydrology, and land cover/land use. Analyzing these types of data with respect to riparian vegetation will help us to evaluate the current status of the riparian habitat and important associated ecological factors that help maintain it. Approximately 20 different GIS layers have been compiled, and many have been analyzed with respect to riparian vegetation. Overlay analysis of soils indicates a strong relationship between riparian vegetation and soil types. For example, along the Rio Grande in the three-county study area, four soils are associated with approximately 60 percent of the existing riparian habitat. GIS-based spatial models and statistical modeling results should help us predict the expected future effects of factors such as landscape change on plant distribution and functional organization at multiple scales of resolution. For instance, landscape-altering dams, levees, and water diversion have dramatically affected the hydrology in the region, as exemplified by reductions in the width of the Rio Grande floodplain and the river channel itself, which, near its mouth, has been reduced from at least 330 m in the mid-1800s to only about 30 m today (Lonard, et al., in press). Reductions in the width of the floodplain have undoubtedly affected the distribution of riparian forested and scrub/shrub habitat, as well as the area in which it can be reestablished.
References:
Jahrsdoerfer S, Leslie DM, Jr. Tamaulipan brushland of the Lower Rio Grande Valley of South Texas: description, human impacts, and management options. U.S. Fish and Wildlife Service Report 1998;88(36):63.
Lonard RI, Judd FW, Everitt JH, Escobar DE, Davis MR, Crawford MM, Desai MD. Riparian vegetation at the mouth of the Rio Grande. In: Proceedings of the 18th Biennial Workshop on Color Photography and Videography in Resource Assessment, University of Massachusetts at Amherst, May 16-18, 2001 (in press).
Future Activities:
Plans are to continue acquiring needed data, classifying and ground-truthing remotely sensed data, completing vegetation transects, entering data into our GIS, analyzing and applying models to define riparian relationships with other mapped characteristics, presenting results in publications and at conferences, and completing the final report.Journal Articles on this Report : 1 Displayed | Download in RIS Format
Other project views: | All 20 publications | 3 publications in selected types | All 2 journal articles |
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Type | Citation | ||
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Lonard RI, Judd FW. Riparian vegetation of the Lower Rio Grande. Southwestern Naturalist 2002;47(3):420-432. |
R827677 (2001) R827677 (2002) R827677 (2003) R827677 (Final) |
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Supplemental Keywords:
remote sensing, watersheds, land, sediments, ecological effects, ecosystem, habitat, integrated assessment, ecology, scaling, modeling, Gulf Coast., RFA, Scientific Discipline, Geographic Area, Ecosystem Protection/Environmental Exposure & Risk, Hydrology, Southwest, Ecology, Environmental Chemistry, Ecosystem/Assessment/Indicators, State, Ecological Effects - Environmental Exposure & Risk, Regional/Scaling, Ecological Risk Assessment, ecological exposure, EMAP, semi-arid environments, Texas, Riparian ecosystem, floodplain communities, ecological assessment, environmental data, anthropogenic, regional scale impacts, Rio Grande Riparian Corridor, agriculture, GIS, landscape patterns, remotely sensed data, land use, scaling methodsProgress and Final Reports:
Original AbstractThe perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.