Geospatial Analysis of Reflectance and NDVI Values in the Angelina Forest Ecosystem

The aerial photographs and subsequently remote sensed imagery have been used for decades in classified landcover mapping, forest inventory, management, and evaluation of renewable resources. However, the implementation of geostatistical methods in remote sensing is of a newer date. In this study the variogram modeling is used to analyze the spatial structure of a forest canopy. The biomass and wood production can be evaluated in the studied area using NDVI (normalized difference vegetation index) values and kriging. The study area is located within the Angelina National Forest in the Neches River Basin. The Angelina Forest is an important part of the East Texas Ecosystem and plays a significant role in all aspects of the natural and industrial development of this region including timber production, forage, wildlife, recreation and as a water resource

Propagation of Errors in Spatial Analysis

In most spatially oriented projects, the conversion of data from analog to digital form used to be an extremely time-consuming process. At present, industrial and research institutions continue to accumulate large quantities of data that are easily accessible to users worldwide, and consequently less time is spent for data input. In addition, the introduction of Internet2 rapidly increased the transfer of spatial data through the electronic highway and opened new avenues for collaboration among research institutions and scientists. It is apparent that this trend will continue in the future. New regional and national centers for spatial data are being established with the objective of providing data to natural resource institutions and developing a high-resolution database of regional significance. Therefore the questions of spatial data accuracy and quality are of utmost importance. The purpose of this paper is to discuss the propagation of errors, outline the major trends and problems that are encountered during spatial data analysis, and demonstrate the propagation of errors during raster data conversion in a GIS environment. The results of this study will contribute to an understanding of errors emanating from the conversion of irregularly spaced points to regular grids using different interpolation methods

Dynamic screening of agricultural contaminants in freshwater ecosystems as part of amphibian biodiversity conservation

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Ruminal Fermentation of Propylene Glycol and Glycerol

Bovine rumen fluid was fermented anaerobically with 25 mM R-propylene glycol, S-propylene glycol, or glycerol added. After 24 h, all of the propylene glycol enantiomers and approximately 80% of the glycerol were metabolized. Acetate, propionate, butyrate, valerate, and caproate concentrations, in decreasing order, all increased with incubation time. Addition of any of the three substrates somewhat decreased acetate formation, while addition of either propylene glycol increased propionate formation but decreased that of butyrate. R- and S-propylene glycol did not differ significantly in either their rates of disappearance or the products formed when they were added to the fermentation medium. Fermentations of rumen fluid containing propylene glycol emitted the sulfur-containing gases 1-propanethiol, 1-(methylthio)propane, methylthiirane, 2,4-dimethylthiophene, 1-(methylthio)-1-propanethiol, dipropyl disulfide, 1-(propylthio)-1-propanethiol, dipropyl trisulfide, 3,5-diethyl-1,2,4-trithiolane, 2-ethyl-1,3-dithiane, and 2,4,6-triethyl-1,3,5-trithiane. Metabolic pathways that yield each of these gases are proposed. The sulfur-containing gases produced during propylene glycol fermentation in the rumen may contribute to the toxic effects seen in cattle when high doses are administered for therapeutic purposes

The Mapping of Composite Pollen from Point Sampled Data and Cartographic Generalization

Pollen grains are microgametophytes produced by angiosperm and gymnosperm plants. They are responsible for transporting genetic material and carrying out fertilization. The study of pollen has numerous practical applications such as plant biodiversity, paleoclimatology, archaeology, allergy studies, the study of nectar sources in honey (melissopalynology), searching for sources of petroleum, and more recently, using pollen as a trace evidence component in forensics. Once pollen grains become airborne, their dispersal is controlled by a number of physical factors that determine the deposition distance from their source area. The purpose of this work is to study spatial pattern of composite pollen in Big Bend National Park using pollen information contained in the top soil layer, test the accuracy of four interpolation methods and use cartographic generalizations to present the results. The focus is on a composite pollen group that is a member of the Asteraceae plant family and is a prolific producer of airborne pollen (Figure 1). FIGURE 1 POLLEN GRAIN OF HELIANTHUS (ASTERACEAE

Towards a food web based control strategy to mitigate an amphibian panzootic in agricultural landscapes

While the emerging amphibian disease chytridiomycosis is causing dramatic and ongoing biodiversity losses worldwide, sustainable strategies to mitigate this global threat to amphibians are currently missing. We here propose a conceptual framework for a novel biological mitigation strategy based on the increasing evidence that naturally occurring micropredators, such as protists, rotifers and crustaceans, are capable of using zoospores of the chytrid pathogens Batrachochytrium dendrobatidis (Bd) and Batrachochytrium salamandrivorans (Bsal) as a food source under controlled laboratory conditions. Pathogen predation may serve as a cost-efficient way to prevent chytridiomycosis outbreaks under natural conditions by reducing zoospore densities and thereby infection loads. This predator-pathogen relationship is not an isolated interaction, but is embedded in the aquatic food web structure that interacts with a wide range of environmental factors. Amphibian breeding ponds are increasingly associated to agricultural landscapes due to ongoing land use occupancy for food production, exposing these water bodies to a variety of environmental stressors such as agrochemical pollution, nutrient enrichment and cattle trampling. Environmental stressors may affect the composition and abundance of aquatic communities, while they can also exert sublethal effects that may reduce the zoospore removal efficiency of micropredators. By carefully controlling environmental stressors, trophic interactions may be steered to optimize chytrid predation with the aim of reducing zoospore densities to such extent that hosts and pathogens can sustainably coexist. We present a scientific outline of this novel concept and provide a framework for ongoing research to develop a complete mitigation strategy against chytridiomycosis based on such food web control