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Color infrared photography and airborne ATLAS images were utilized to develop a vegetation map and a supervised land-cover classificationfor the Blue Canyon reach of Moenkopi Wash on the Hopi Reservation, Arizona. An orthophoto mosaic was produced, enabling photointerpretation of riparian vegetation within the study area. Polygons representing homogeneous vegetation patches were delineated using stereo pairs and ground verification techniques. Vegetation transects measured percent cover and species composition. The Spence-Romme-Floyd-Rowlands vegetation classification scheme served as a framework to map the vegetation. Image processing techniques such as Tasseled Cap transformations and image masking were used in an attempt to minimize soil noise from the ATLAS images prior to classification. Land-cover classification accuracy for the pilot study area was 40 percent. TNDVI and MSAVI2 vegetation indices were evaluated for their ability to indicate vegetation extent and relative plant vigor. [ABSTRACT FROM AUTHOR]

Rainfall-simulation experiments have been carried out on a series ofplots ranging in size from 1 m2 to c 500 m2 inorder to observe process and flux-rate changes resulting from the replacement of the dominant vegetation type from grassland to shrublandin the American South-west. Results have demonstrated variations in infiltration rates, flow hydraulics, splash and interrill erosion rates and nutrient transport rates. Furthermore, the shrubland areas develop rills, which are responsible for significant increases in overall erosion rates. The small-plot experiments allow the definition of controlling factors on the processes, and highlight the importance of vegetation controls. Although the small-plot approach has a number ofsignificant advantages, it also has a number of disadvantages, whichare discussed in detail. Some of these problems can be overcome witha careful consideration of experimental design. It is argued that plot-scale studies play an important part in improving our understanding of complex, open systems, but need to be integrated with other approaches such as the monitoring of natural events and computer modelling so that mutually consistent understandings of complex ecohydrological systems can be achieved. [ABSTRACT FROM AUTHOR]