Effects of fire on certain physical properties of selected chaparral soils

Wildfires have burned through chaparral environments of southern California for at least 100,000 years. Surface temperatures of up to 800° c. have been recorded during such fires. Under these conditions, the physical properties of the soil may be altered, and soil characteristics such as porosity, permeability, stability, and susceptibility to erosion by water and wind may be effected. This study focuses on fire's effect on the inorganic particles present in certain chaparral soils, and the implications of this effect to the soil-water environment. Samples of two different soils from southern California chaparral areas were analyzed for color, pH, particle size distribution, and mineralogy. The samples were subjected to wildfire conditions in the laboratory, and changes in these soil properties were observed. Soil color was found to change from lighter to darker. The pH of each soil increased after heating; one soil was found to vary from pH 7.4 to pH 9.6 after heating to 800° c, and the other exhibited a variation from 6.3 to 8.3. The particle size distribution of each soil displayed a shift in frequency of grain sizes. (See more in text.)Includes bibliographical references (pages 49-51)California State University, Northridge. Department of Geography

Cloud Coverage Acts as an Amplifier for Ecological Light Pollution in Urban Ecosystems

The diurnal cycle of light and dark is one of the strongest environmental factors for life on Earth. Many species in both terrestrial and aquatic ecosystems use the level of ambient light to regulate their metabolism, growth, and behavior. The sky glow caused by artificial lighting from urban areas disrupts this natural cycle, and has been shown to impact the behavior of organisms, even many kilometers away from the light sources. It could be hypothesized that factors that increase the luminance of the sky amplify the degree of this “ecological light pollution”. We show that cloud coverage dramatically amplifies the sky luminance, by a factor of 10.1 for one location inside of Berlin and by a factor of 2.8 at 32 km from the city center. We also show that inside of the city overcast nights are brighter than clear rural moonlit nights, by a factor of 4.1. These results have important implications for choronobiological and chronoecological studies in urban areas, where this amplification effect has previously not been considered

The relation of outdoor lighting characteristics to sky glow from distant cities

Five cities in the southwest United States were selected for an analysis of the impact of outdoor lighting practices on nighttime sky glow as observed from distances of 8–67 km. Data from the Suomi National Polar-orbiting Partnership (NPP) satellite visible infrared imaging radiometer suite day/night band were used to identify light sources for input to an atmospheric sky glow model. Total lumens of outdoor lighting were estimated by matching modelled to observed anthropogenic sky luminance at ground locations. The results of two conservative treatments were then modelled for each city: all outdoor luminaires fully shielded with the current lumen amount, and fully shielded luminaires with a lumen amount scaled to 2075 lm capita−1, matching Flagstaff, Arizona. The results indicate 42–88% reductions in average all-sky glow utilizing these ‘best practices’ for environmental conservation. </jats:p