RCMAP - Time-Series - Trends

The RCMAP product suite includes 10 components: annual herbaceous, bare ground, herbaceous, litter, non-sagebrush shrub, perennial herbaceous, sagebrush, shrub, tree, and shrub height. Data characterize the percentage of each 30-meter pixel in the Western United States covered by each component for each year from 1985-2023 - providing change information for 39 years. 

We assess the temporal patterns in each RCMAP component with two approaches, 1) linear trends and 2) a breaks and stable states method with a temporal moving window based on structural change at the pixel level. Linear trend products include slope and p-value calculated from least squares linear regression. The slope represents the average percent cover change per year over the times-series and the p-value reflects the confidence of change in each pixel, see Shi et al. 2022 for more detail.. The structural change method partitions the time-series into segments of similar slope values, with statistically significant break-points indicating perturbations to the prior trajectory. 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. We produce the following statistics: 1) for each component, each year, the presence/absence of breaks, 2) the slope, p-value, and standard error of the segment occurring in each year, 3) the overall model R2 (quality of model fit to the temporal profile), and 4) an index, Total Change Intensity. This index reflects the total amount of change occurring across components in that pixel.

Preferred Citation

Rigge, M.B., Bunde, B., Postma, K., and Shi, H., 2024, Rangeland Condition Monitoring Assessment and Projection (RCMAP) Fractional Component Time-Series Across the Western U.S. 1985-2023: U.S. Geological Survey data release, https://doi.org/10.5066/P9SJXUI1.

Related Citations:

Shi, H., Rigge, M., Postma, K., and Bunde, B. 2022. Trends analysis of rangeland condition monitoring assessment and projection (RCMAP) fractional component time series (1985-2020). GIScience & Remote Sensing. 59: 1243-1265.

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.