Remote Sensing of Giant Reed with QuickBird Satellite Imagery

QuickBird high resolution (2.8 m) satellite imagery was evaluated for distinguishing giant reed ( Arundo donax L.) infestations along the Rio Grande in southwest Texas. (PDF has 5 pages.

Spectral Reflectance and Digital Image Relations Among Five Aquatic Weeds

This study reports on the use of an artificial quartz halogen lighting source to facilitate the acquisition of spectral light reflectance measurements and digital imaging of invasive aquatic weeds. Spectral leaf or leaf/stem reflectance measurements were made on five aquatic weeds: Eurasian watermilfoil (Myriophyllum spicatum L.), hydrilla [Hydrilla verticillata (L. F.) Royle], parrotfeather [Myriophyllum aquaticum (Vall.), waterhyacinth [Eichhornia crassipes (Mart.) Solms], and waterlettuce (Pistia stratiotes L.). Reflectance measurements were studied at five wavelengths of the electromagnetic spectrum: 450 nm (visible blue), 550 nm (visible green), 650 nm (visible red), 680 nm (visible red edge), and 850 nm (near-infrared). Reflectance values differed significantly (P= 0.05) among the species at all five wavelengths. However, more distinct separations among species occurred at the 550 nm, 650 nm, 680 nm, and 850 nm wavelengths. Reflectance differences among species were attributed to variable foliage coloration and vegetative density. Close range conventional color and color-infrared digital images of leaves or leaves/stems of the five species showed they differed in image tonal response. Reflectance measurements were related to the image tonal response of the plant species on both types of imagery. Supervised image classifications performed on both conventional color and color-infrared images showed the computer generally did an adequate job in identifying the image tonal responses of the weed species

Cissus sicyoides C. Linnaeus (Vitaceae), a Potential Exotic Pest in the Lower Rio Grande Valley, Texas

English:Cissus sicyoides C. Linnaeus, a perennial vine native to tropical Mexico, Central America, and the Caribbean, has recently been rediscovered in the Lower Rio Grande Valley,Texas. A dense population of this exotic species has been located in a brushy area along a canal network and in two adjacent citrus groves near Weslaco. This species produces a dense mantle that covers other vegetation, appears to be invasive, and may pose a potential weed problem in citrus in the Lower Rio Grande Valley. Spanish: Cissus sicyoides C. Linnaeus, una enredadera perene nativa de los trópicos de México, América Central y el Caribe, se ha redescubierto recientemente en el Bajo Valle del Río Grande,Texas. Una población densa de esta especie exótica ha sido localizada en una área de matorral a lo largo de una red de canales y en dos huertas adyacentes de cítricos cercanas a Weslaco. Esta especie produce un manto denso que cubre otra vegetación, es invasiva y puede tener el potencial de convertirse en una maleza problemática para el cultivo de cítricos en el Bajo Valle del Río Grande en Texas

Woody Plants of the Lower Rio Grande Valley, Texas

Description of Common Vegetation of Lower Rio Grande Valley

Examining Healthcare Institutions by Bringing Qualitative Data from Two Eras into Empirical Dialogue

In this paper, we argue that there is new insight to be gained by reexamining the classic text, Boys in White, in strategic ways. Specifically, we share excerpts from Boys in White with current medical students and ask for their reactions in qualitative interviews, examining the relevance (or lack thereof) of earlier meanings about professional training for current processes of professional training. We show how we have employed this technique in our current project revisiting Boys in White with current medical students, and discuss preliminary findings that reveal the potential of this technique for documenting evidence of macro-level forces in healthcare institutions using qualitative data on new doctors. We conclude with discussion of alternative approaches through which scholars could make use of this technique in future professional socialization scholarship that could shed light on dynamics of institutional persistence and change

Use of Archive Aerial Photography for Monitoring Black Mangrove Populations

A study was conducted on the South Texas Gulf Coast to evaluate archive aerial color-infrared (CIR) photography combined with supervised image analysis techniques to quantify changes in black mangrove [Avicennia germinans (L.) L.] populations over a 26-year period. Archive CIR film from two study sites (sites 1 and 2) was studied. Photographs of site 1 from 1976,1988, and 2002 showed that black mangrove populations made up 16.2%, 21.1%, and 29.4% of the study site, respectively. Photographs of site 2 from 1976 and 2002 showed that black mangrove populations made up 0.4% and 2.7% of the study site, respectively. Over the 26-year period, black mangrove had increases in cover of 77% and 467% on sites 1 and 2, respectively. These results indicate that aerial photographs coupled with image analysis techniques can be useful tools to monitor and quantify black mangrove populations over time

An Overview of Aircraft Remote Sensing in Integrated Pest Management

English: This paper presents four exemplary applications of aerial photography and videography, global positioning system (GPS), and geographic information system (GIS) technologies for detecting, monitoring, and mapping insect infestations in agriculture, forestry, and rangeland areas. Applications demonstrated include detecting and mapping: (1) citrus blackfly (Aleurocanthus woglumi Ashby) infestations in citrus orchards; (2) silverleaf whitefly (Bemisia argentifolii Bellows and Perring) infestations in cotton; (3) harvester ant (Pogonomyrmex barbatus F. Smith) infestations on rangelands; and (4) western pine beetle (Dendroctonus brevicomis LeConte) infestations in a forested area. The integration of a GPS with the video imagery permitted latitude and longitude coordinates of insect infestations to be recorded on each image. The GPS coordinates were entered into a GIS to map insect infestations on a regional scale. The integration of remote sensing, GPS, and GIS provide valuable tools that can enable resource managers to develop maps showing the distribution of insect infestations over large areas. The digital imagery can serve as a permanent geographically located image data base for monitoring future contraction or spread of insect infestations over time. Spanish: En este artículo se presentan cuatro ejemplos de las aplicaciones de las tecnologías de fotografía y videografía aéreas, el sistema de posición global (GPS), y del sistema de información geográfica (GIS) para la detección, monitoreo, y mapeo de infestaciones de insectos en áreas agrícolas, forestales y en pastizales. Las aplicaciones demonstradas incluyeron la detección y el mapeo de (1) infestaciones por la mosca negra de los cítricos (Aleurocanthus woglumi Ashby) en huertas de cítricos; (2) mosquita blanca (Bemisia argentifolii Bellows and Perring) en algodón; (3) hormiga cosechadora (Pogonomyrex barbatus F. Smith) en pastizales; y (4) escarabajo del pino del oeste (Dendroctonus brevicomis Le Conte) en una área forestal. La integración del sistema de GPS con las imágenes de video permitió registrar las coordenadas de longitud y latitud en cada imagen. Las coordenadas de cada imagen se incorporaron en un mapa de GIS para crear un mapa de las infestaciones de insectos a una escala regional. La integración de un sistema de detección a distancia, GPS, and GIS brinda herramientas valiosas para permitir a los supervisores de recursos desarrollar mapas que muestren la distribución de infestaciones de insectos en áreas extensas. El sistema de imágenes digital puede servir como una base permanente de datos localizados geográficamente para el monitoreo de futuras concentraciones o dispersiones de plagas de insectos a lo largo del tiempo

Aerial detection of waste disposal sites near Donna Reservoir in south Texas.

Aerial color-infrared (CIR) photography was used to detect and catalog unauthorized solid waste disposal sites around Donna Reservoir in the Lower Rio Grande Valley (LRGV) of southern Texas. Qualitative visual evaluation of the positive transparencies showed 25 possible disposal sites randomly scattered throughout the study area, located in sites ranging from bare soil to grass and mixed brush/woods. These sites were transposed onto a computer-generated area map for ground survey confirmation and use by organizations planning to clean-up the sites. Ground-truthing was used to identify waste contents at each site and to estimate waste volumes and areas covered. Unauthorized solid waste sites were verified in 23 of the 25 locations. Two sites contained only broken concrete and asphalt being utilized as erosional fill material. The ground survey identified ten solid waste sites missed on the aerial photos. These sites were missed due to their small size (\u3c 2 [m.sup.2]) and because they were covered by lodging guinea grass (Panicum maximum) or giant reed (Arundo donax). The addition of these missed sites to the other 25 locations hindered the overall accuracy of the aerial photographic survey (71.4%)

Detection of Temporal Changes in Vegetative Cover on South Padre Island, Texas Using Image Classifications Derived from Aerial Color-Infrared Photographs

Supervised image classifications developed from 23 x 23 cm aerial color-infrared aerial photographs (1:5,000 scale) were used to evaluate temporal changes in vegetative cover occurring within three 150 x 300-m research sites on South Padre Island, Texas. Use of high-resolution digitized imagery (ground pixel resolution of ca. 0.1 m) and survey-grade GPS for positional measurements of ground control points (20-25 1.0m2 targets within each research site) resulted in consistently high levels of geometric accuracy, with root mean square errors (RMSEs) ranging between 0.397 – 2.867. Similarly, use of relatively simple information categories (dry and wet sand, live and dead vegetative cover, and water) resulted in supervised image classifications with consistently high levels of overall thematic accuracy (90.0 – 98.0%). Temporal comparisons of image classifications using a cross-tabulation procedure indicated that changes in total vegetative cover had been minimal at most locations during the course the two-year study (2003-2005). However, a localized but significant disruption of native vegetation caused by the dumping of sand by highway maintenance crews was detected in one of the study sites (2004), and ground inspection revealed numerous other sand-dumping sites at various locations on the barrier island. In the first situation, comparison of CIR aerial photographs acquired before and after the sand-dumping incident provided a reliable means by which to evaluate the extent of damage caused by the dumped sand, and to monitor its eventual recovery as a result of recolonization by native plant species

Detection of Incipient Pest Infestations on Glasshouse Crops Using Multispectral Imagery and a Common Vegetation Index

Research was conducted to evaluate the effectiveness of multispectral (conventional color and color infrared) imagery and a common vegetation index (simple ratio) for detecting incipient infestations of spider mites (Tetranychus spp.; Acari: Tetranychidae) and false spider mites (Brevipalpus spp.; Acari: Tenupalpidae) on selected crops under glasshouse conditions. Although damaging infestations of both mite species were associated with intense feeding injury which was readily detectable by visual inspection, subtle levels of foliar damage caused by the two mite species were difficult to detect by visual inspection and were not readily distinguishable from undamaged (healthy) foliage in conventional color (CC) or color infrared (CIR) imagery. In contrast, foliage exhibiting subtle levels of mite feeding injury was readily distinguished from healthy foliage in derivative imagery based on the Simple Ratio (SR), a vegetation index defined as the ratio of near-infrared to red reflectance (700-1100 nm and 600-700 nm, respectively) for each pixel in the imagery. CIR and SR images were shown to be considerably more effective than CC imagery in the initial detection and subsequent monitoring of a spider mite infestation on glasshouse cucumbers which increased from incipient to annihilative levels within a period of approximately six weeks. The rationale for and potential uses of CC, CIR, and derivative imagery based on SR and other vegetative indices for monitoring pest infestations on glasshouse crops are discussed