Grantee Research Project Results
2002 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, 2001 through August 31, 2002
Project Amount: $642,496
RFA: Regional Scale Analysis and Assessment (1999) RFA Text | Recipients Lists
Research Category: Aquatic Ecosystems , Ecological Indicators/Assessment/Restoration
Objective:
The objectives of this research project are to: (1) acquire and analyze high-resolution, remotely sensed data from multiple sensors; (2) integrate existing and new field data and remotely sensed data into a geographic information system (GIS); (3) ascertain whether the native vegetation communities are maintaining themselves and identifying the topographic, edaphic, and other ecological factors that perpetuate these communities; (4) interpret spatial variations in riparian habitats, including comparisons of the north and south banks of the Rio Grande; (5) analyze temporal changes at specific locations; and (6) develop a foundation for future analysis of riparian floodplain communities by linking local and remotely sensed regional data using GIS. 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 study is focused on riparian communities along the Lower Rio Grande Valley of Texas and Mexico.
Progress Summary:
Progress during the third year primarily was made in the areas of current land-use mapping, vegetation surveys, climate analysis, remote data classification, data acquisition, GIS development, and analysis/modeling in the GIS environment. Work on land-use mapping by the University of Texas, Brownsville (UTB) continued in 2002. Currently, UTB researchers are in the final stages of editing land-use maps, and have completed a series of climate maps to be used as overlays. Digital maps of land-use for the years 1960 and 1995 have been completed, and an overlay for the year 2000 has been assembled. Analysis of 1995 and 1960 data shows an explosive growth of residential urban parcels, particularly in the McAllen-Pharr-Edinburg area. Mapping of woodland shows very little of this category left in Hidalgo County. The year 2000 U.S. Census data for the four counties of the Lower Rio Grande Valley of Texas show a combined population approaching 1 million people. The land-use maps graphically indicate how this growth has impacted natural vegetation. Analysis of climate data, which include average annual precipitation, September precipitation, average annual temperature, January mean temperature, July mean temperature, heating degree days, and cooling degree days show "heat islands" encircling both the McAllen and Brownsville urban areas.
The University of Texas, Pan American investigators continued collecting field data on vegetation species composition. A new vegetation analysis site was established at the McManus Unit of the Texas Parks and Wildlife Department. This site is located approximately 8 km east of the Santa Ana National Wildlife Refuge (NWR), Hidalgo County, TX. It is undisturbed native woodland located 1.2 km north of the Rio Grande, but within the historical floodplain of the river. To census the vegetation, ten 10 m by 10 m quadrants were established at randomly determined locations. Censusing of tree, shrub, and ground layers was done separately. The McManus site is not a close match in species composition and structure to any of the seven sites that we examined along the Rio Grande (Lonard and Judd, 2002), and it considerably differs from a native woodland site described by Judd, et al. (2002) at a place 33 km northeast of Cameron County.
A much more concentrated effort to delineate the distribution of various classes of riparian vegetation in the study area was conducted by the Center for Space Research and Bureau of Economic Geology during this project period. We continued our efforts to use large scale color infrared (CIR) photography with 1 m resolution along with field surveys and high-resolution (4 to 7 m) spectrally calibrated hyperspectral data to train classification algorithms for analysis of riparian vegetation in the Santa Ana NWR, which contains one of the largest contiguous riparian communities along the Rio Grande. These analyses were used to scale upward using medium-resolution Landsat 7 Thematic Mapper (TM) data that cover the entire Lower Rio Grande Valley. The TM data have extensive areal coverage but lower spatial and spectral resolution than that of hyperspectral data, and lower spatial resolution than Digital Orthophoto Quadrangle (DOQ) data. Our classification of riparian vegetation communities defines five classes on the basis of the presence of evergreen and deciduous species, as well as combinations of the two. This classification is modeled after the U.S. Fish and Wildlife Association (USFWS) National Wetlands Inventory program, in which riparian vegetation inventory and mapping conventions were developed for the Western United States. Composition of vegetation was determined from field surveys and interpretation of high-resolution, digital CIR aerial photographs (DOQs) acquired during winter months.
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 helps us evaluate the current status of the riparian habitat as well as evaluate the important associated ecological factors that help maintain the habitat. For example, analysis of the relationship between riparian vegetation classified from hyperspectral data and soils from the Natural Resources Conservation Service Soil Survey Geographic Database (SSURGO) in the southern half of the Santa Ana NWR shows that the dominant soil on which riparian vegetation was mapped is the Rio Grande Silt Loam. Between 40 and 50 percent of each riparian class (deciduous, evergreen, and mixed) occurs on this soil. Other major soils on which riparian vegetation classes were mapped are Zalla Loamy Fine Sand and Matamoros Silty Clay. Results suggest that evergreen vegetation in this area frequently is more associated with silty and silty clay soils. Only 2 percent of evergreen distribution occurred on sandy soil, whereas at least 19 percent of other classes (deciduous and mixed) were associated with sandy soil.
References:
Lonard RI, Judd FW. Riparian vegetation of the lower Rio Grande. Southwestern
Naturalist 2002;47(3):420-432.
Judd FW, Lonard RI, Waggerman GL. Evaluation of facilitated succession at Las Palomas Wildlife Management Area in South Texas. Texas Journal of Science 2002;54(2):163-176.
Future Activities:
Future activities during the extended research period include: (1) acquiring needed data; (2) classifying and ground-truthing remotely sensed data; (3) completing vegetation transects; (4) entering data into our GIS; (5) analyzing and applying models to define riparian relationships with other mapped characteristics; (6) presenting results in publications and at conferences; and (7) 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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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, Southwest, Ecology, Hydrology, Ecosystem/Assessment/Indicators, Environmental Chemistry, 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.