Change detection in rangeland environments using Landsat MSS data: A quantitative approach
A range forage utilization study on the Crow Creek Indian Reservation in central South Dakota provided the opportunity to use Landsat multispectral scanner (MSS) data for examining range condition trends. A procedure was developed to compare change in spectral reflectance over time for polygon areas, defined by resource type within management units. A t-test was used to evaluate changes in brightness and greenness within pastures between September 27, 1978, and September 18, 1983. The first principal component transformation from four-band MSS images for both dates was used as a measure of brightness. Greenness was measure using the second principal component transformation for both dates. Examination of the brightness date showed that the assumptions required for a valid t-test were met. The greenness data violated the assumption of independence between dates and was not used for trend comparisons. The t-values calculated from each polygon were coded into three groups: (1) those indicating significant brightness decrease, (2) those indicating significant brightness increase, and (3) those indicating no significant brightness change. Significance was determine at the 5-percent level. These results were formatted into an image, which is a preliminary product for evaluating range condition trends over a 5-year period.