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

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

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

Teachers' classroom feedback: still trying to get it right

This article examines feedback traditionally given by teachers in schools. Such feedback tends to focus on children's acquisition and retrieval of externally prescribed knowledge which is then assessed against mandated tests. It suggests that, from a sociocultural learning perspective, feedback directed towards such objectives may limit children's social development. In this article, I draw on observation and interview data gathered from a group of 27 9- to 10-year olds in a UK primary school. These data illustrate the children's perceived need to conform to, rather than negotiate, the teacher's feedback comments. They highlight the children's sense that the teacher's feedback relates to school learning but not to their own interests. The article also includes alternative examples of feedback which draw on children's own inquiries and which relate to the social contexts within which, and for whom, they act. It concludes by suggesting that instead of looking for the right answer to the question of what makes teachers' feedback effective in our current classrooms, a more productive question might be how a negotiation can be opened up among teachers and learners themselves, about how teachers' feedback could support children's learning most appropriately

Vegetative Change on South Padre Island, Texas, over Twenty Years and Evaluation of Multispectral Videography in Determining Vegetative Cover and Species Identity

A comparative vegetation analysis of an island-wide transect of South Padre Island, Texas, was conducted in 1997 using aerial multispectral digital videography and line intercept ground truth techniques to assess the usefulness of videography in estimating vegetative cover and species identifications. Ground truth data were used to assess vegetative change occurring in the 20 years since the report of Judd et al. (1977) on the vegetation of South Padre Island. Estimates of total cover by ground truth and remote sensing techniques were similar (2.45% difference) on South Padre Island. Thus, airborne multispectral digital videography is an effective technique for assessing changes in total vegetative cover of Texas barrier islands. This technique will be an effective tool for documenting changes in total cover on barrier islands due to natural perturbations such as hurricanes and human disturbances including vehicular traffic. Imagery obtained at altitudes of 200 m or greater did not permit discrimination of dominant species in each of an island\u27s topographic zones. However, acquisition of imagery at a time of the year when dominant species are in specific phenological stages, such as flowering, and at a lower altitude may facilitate their recognition. Comparison of data from a single trans-island transect in 1997 with data from three trans-island transects and 18 transects across the foreshore, backshore, and primary dunes in 1977 suggests that there has been a marked decrease in species richness of the backshore and primary dune zones of South Padre Island. There also was a change in dominant species in the backshore zone. These changes in species richness and dominance may be largely attributable to vehicular traffic in these zones. - Un análisis comparativo de la vegetación de un transecto transinsular de la isla South Padre en el estado de Texas fue realizado en 1997 usando videografía aérea multiesprectral digital y técnicas de validación de intercepción linear terrestre para evaluar la utilidad de la videografía en la estimación de la cobertura vegetal e identificación de especies. Los datos de estudios de validación terrestre fueron utilizados para evaluar el cambio vegetativo que ocurrió durante 20 años después del informe de Judd et al (1977) sobre la vegetación de la isla South Padre. Las estimaciones de la cobertura total mediante técnicas de validación terrestres y de medición remota fueron similares (2.45% de diferencia) en la isla South Padre. Por lo tanto, la videografía multiesprectral digital aérea se considera una técnica eficaz para evaluar cambios en la cobertura vegetal de las islas barrera de Texas. Esta técnica será una herramienta efectiva para documentar los cambios de cobertura total en las islas barrera debido a las perturbaciones naturales tales como huracanes y disturbios humanos como tráfico vehicular. Las imágenes obtenidas en altitudes de 200 metros o mayores no permitieron la discriminación de las especies dominantes de las varias zonas topográficas de una isla. Sin embargo, la adquisición de imágenes de una época del año en que las especies dominantes están en etapas fenológicas específicas, tales como la floración, y desde una altitud menor, puede facilitar su reconocimiento. Al comparar datos de un transecto transinsular de 1977 con los de tres transectos transinsulares y de 18 transectos correspondientes a la parte frontal, trasera, y de las dunas primarias de la isla en 1977, se sugiere que ha habido una marcada disminución en la riqueza de especies en la parte trasera y en la zona de dunas primarias de la isla South Padre. También hubo un cambio de especies dominantes en la zona trasera. Estos cambios en la riqueza y dominancia de especies pueden ser atribuidos en gran parte al tráfico vehicular en estas zonas