An improved technique for the prediction of optimal image resolution(s) for large-scale mapping of savannah ecosystems

Past studies to predict optimal image resolution required for generating spatial information for savannah ecosystems have yielded different outcomes, hence providing a knowledge gap that was investigated in the present study. The postulation, for the present study, was that by graphically solving two simultaneous equations of values of image noise index (INI) and degradation level Index (LDI), a robust technique for predicting optimal image resolution for the mapping of savannah ecosystems was developed. The technique involved simulating 0.5 m imagery to different spatial resolutions for two savannah test sites in Masaka district, Southern Uganda. By plotting INI and LDI values against the simulated image resolutions, it enabled the authors to objectively predict that image resolution at 2.25 and 2.5 m were optimal for generating spatial information for savannah ecosystems represented by the two test sites. The new technique will enable vegetation ecologists to objectively determine optimal resolution(s) prior to the choice of imagery, offered by different high-resolution air- and space-borne sensors, for generating spatial information for savannah ecosystems. Future research should focus on using the new technique to determine what ranges of image resolutions are optimal for generating spatial information of different savannah ecosystems in different countries.Key words: Optimal resolution, savannah ecosystems, image noise index, land cover index, level of degradation index

Occurrence of Didymella ascospores in western and southern Poland in 2004–2006

The concentration of airborne Didymella spores has been investigated at two monitoring sites situated along the west–south transect in Poland (Szczecin, Kraków), i.e. from a height of 100 to 219 m, respectively, above sea level. The aerobiological monitoring of fungal spores was performed by means of two Lanzoni volumetric spore traps. The high Didymella spore numbers were observed at both cities in June, July and August. Statistically significant correlations have been found mainly between the Didymella spore concentrations in the air and the minimum air temperature and relative air humidity. The spore count of Didymella is determined by the diversity of local flora and weather conditions, especially by the relative air humidity. The identification of factors that influence and shape spore concentrations may significantly improve the current methods of allergy prevention

Long-term accumulation and transport of anthropogenic phosphorus in three river basins

Global food production depends on phosphorus. Phosphorus is broadly applied as fertilizer, but excess phosphorus contributes to eutrophication of surface water bodies and coastal ecosystems1. Here we present an analysis of phosphorus fluxes in three large river basins, including published data on fertilizer, harvested crops, sewage, food waste and river fluxes2, 3, 4. Our analyses reveal that the magnitude of phosphorus accumulation has varied greatly over the past 30–70 years in mixed agricultural–urban landscapes of the Thames Basin, UK, the Yangtze Basin, China, and the rural Maumee Basin, USA. Fluxes of phosphorus in fertilizer, harvested crops, food waste and sewage dominate over the river fluxes. Since the late 1990s, net exports from the Thames and Maumee Basins have exceeded inputs, suggesting net mobilization of the phosphorus pool accumulated in earlier decades. In contrast, the Yangtze Basin has consistently accumulated phosphorus since 1980. Infrastructure modifications such as sewage treatment and dams may explain more recent declines in total phosphorus fluxes from the Thames and Yangtze Rivers3, 4. We conclude that human-dominated river basins may undergo a prolonged but finite accumulation phase when phosphorus inputs exceed agricultural demand, and this accumulated phosphorus may continue to mobilize long after inputs decline