Abstract: By using landscape pattern analysis based on GIS, this paper studied the grain effect of landscape pattern indices with a scale 1-50 m in a gully catchment of the Loess Plateau, China from 1975 to 2007. In the catchment, the grain effect was obvious, and differed significantly with year. The grain effect had five types, i.e., stable, stable decreasing, undulatory decreasing, amplitude-accreting, and anomalistic changing. With increasing grain, the stable grain effect showed a stable patch richness density, the stable decreasing grain effect showed a decreasing trend of total edge, edge density, landscape shape index, aggregation index, and contagion index, the undulatory decreasing grain effect showed an undulatory decreasing trend of perimeter-area fractal dimension, the amplitude-accreting grain effect showed an amplitude increasing trend of total area, Shannon’s diversity index, and evenness index, and the anomalistic changing grain effect showed an anomalistic change of patch number, patch density, mean patch area, largest patch index, splitting index, and landscape division index. In 1975, the grain effect of all the indices differed significantly from that in other years, and even, was in opposite.

Key words: landscape pattern, scale, grain effect, gully catchment of Loess Plateau, mollisols, long-term fertilization, soil organic carbon, soil particles, enrichment factor.