The RCMAP product suite includes eight fractional components: annual herbaceous, bare ground, herbaceous, litter, non-sagebrush shrub, perennial herbaceous, sagebrush and shrub, rule-based error maps, and the temporal trends of each. Data characterize the percentage of each 30-meter pixel in the Western United States covered by each component for each year from 1985-2020 - providing change information for 35 years (imagery for 2012 was unavailable). Because of file size limitations, individual component products are packaged in three historic intervals including 1985-1995, 1996-2006, and 2007-2020.
Trend analysis for each component will be available in July 2021 for the full 1985-2020 period to help users understand the magnitude of change. We analyze RMCAP time-series trends using two methods; first, linear trends analysis and second, detection of break points. Linear trend products include slope, standard error and t-statistic calculated from least squares linear regression. The slope represents the average percent cover change per year over the times-series, the standard error measures the departure from the linear slope model across all yearly observations in each pixel and the t-statistic reflects the confidence of change in each pixel. The break point trends analysis suite relies on structural break methods, resulting in the identification of the number and timing of breaks in the time-series, and the significance of each segment.
Preferred citation: Rigge, M., Homer, C., Shi, H., Meyer, D., Bunde, B., Granneman, B., Postma, K., Danielson, P., Case, A., and Xian, G. 2021. Trends in rangelands fractional components across the western U.S. from 1985-2018. Remote Sensing, 13: 813.
Shi, H., M. Rigge, B. Bunde, D. Meyer, and K. Postma. In Preparation. Trends Analysis of 1985-2020 Rangeland Condition Monitoring Assessment and Projection (RCMAP) Fractional Component Time-Series.
Related Publication: Rigge, M., H. Shi, C. Homer, P. Danielson, and B. Granneman. 2019. Long-term trajectories of fractional component change in the Northern Great Basin, USA. Ecosphere: e02762
Shi, H., C. Homer, M. Rigge, K. Postma, and G. Xian. 2020. Analyzing change in a shrubland ecosystem with both long-term field observations and Landsat time-series in Wyoming, USA. Ecosphere: e03311.
Rigge, M., C. Homer, H. Shi, and D. Meyer. 2019. Validating a Landsat time-series of fractional component cover across western U.S. rangelands. Remote Sensing 11, 3009.