Response of surface reflectivity to anthropogenic land cover change in the U.S. High Plains, 1974-1992

Albedo (hemispherical reflectivity integrated across the solar wavelengths) is the most important surface property constraining the amount of solar energy absorbed at the Earth´s surface. It is therefore crucial to understand the spatio-temporal dynamics of albedo resulting from land cover variability. The authors used surface reflectivity (as a surrogate for albedo) calculated from Landsat MSS data to analyze the effects of anthropogenic land cover change in southwestern Kansas, a region which has undergone significant land cover change in the last three decades. They analyzed seasonal image series for three years (1974, 1983, 1992) at full resolution and rescaled by simple averaging at factors of 2, 4, 8, and 16. Lacunarity indices were used to quantify changes in spatial scale and pattern of surface reflectivity. For each scene, they partitioned the image histogram into four reflectivity classes to generate separate binary classified images. They then calculated the percent deviation of observed lacunarity from its neutral expectation for each reflectivity class across dates and rescalings. They observed (1) seasonal patterns in lacunarity, (2) climatic influence on lacunarity, (3) decreasing resolution tends to attenuate deviations of lacunarity, and (4) climatic variability perhaps masking unidirectional land cover change