This work centers on using remote-sensing tools and protocols for monitoring long-term changes in vegetation cover across the WLCI region. This information is crucial for understanding patterns of change within sagebrush habitats, including historical changes and potential trajectories of future changes. Our study targets five components of vegetation cover: all shrubs, sagebrush shrubs, herbaceous vegetation, litter, and bare ground, which we quantify by one-percent intervals. Based on samples collected both in the field and from satellite imagery, the USGS can evaluate and quantify the amount and distribution of long-term changes in the target components. This work and its associated products represent the operational vegetation monitoring effort for the WLCI, and they provide input to a broad spectrum of on-going WLCI research and conservation and restoration applications.
During FY2014, our on-the-ground vegetation monitoring continued in plots along 260 marked transects distributed across two QuickBird (18 square kilometers [km2] each) satellite scenes for assessing long-term changes. The plots have been sampled since 2006 providing nearly a decade-long record of change that we use to understand trends observed in satellite images and extrapolate them to the WLCI landscape. We also use Landsat satellite images that include our study plots to understand how precipitation changes affect sagebrush cover. In FY2014, we began new research to quantify changes in shrub, sagebrush, herbaceous, litter, and bare ground cover across the entire WLCI region from 1985 to 2010, which is made possible by using the Landsat imagery archive. When this effort is completed in FY2015, it will provide a record of vegetation change for every 3 years from 1985 to 2010 within every 30-meter (m) cell of the WLCI region. The procedures and products developed through these efforts will facilitate a broad array of applications for better understanding the historical trajectories of vegetation change.
Products Completed in FY2014
- We acquired and processed Landsat 5 images of the WLCI region for 1985, 1988, 1991, 1993, 1996, 1999, 2003, 2006, 2008, and 2010, and we acquired Landsat 8 images for 2014; the results are being used to backcast predictions of shrub, sagebrush, herbaceous, litter, and bare ground cover across the WLCI area to quantify vegetation change from 1985 to 2010.
- Target vegetation components were measured at 260 plots along marked transect for on-going, ground-based monitoring.
- Homer, C.G., Xian, G., Aldridge, C.L., Meyer, D.K., Loveland, T.L. and O’Donnell, Michael, 2015, Forecasting sagebrush ecosystem components and greater sage-grouse habitat for 2050 -- Learning from past climate patterns and Landsat imagery to predict the future: Ecological Indicators (in revision).
Products Completed in FY2013
- Quickbird and Landsat image collections for WLCI areas.
- Measurement of 260 marked transect plots for ongoing monitoring research.
- Homer, C.G., Meyer, D.K., Aldridge, C.A., and Schell, S., 2013, Detecting annual and seasonal changes in a sagebrush ecosystem with remote sensing derived continuous fields: Journal of Applied Remote Sensing, v. 7, no. 1, at http://remotesensing.spiedigitallibrary.org/article.aspx?articleid=1735848.
- Homer, C.G., Xian, G., Aldridge, C.L., Meyer, D.K., Loveland, T.L. and O’Donnell, M., Forecasting sagebrush ecosystem components and greater sage-grouse habitat for 2050 - Capitalizing on 28 years of Landsat satellite imagery and climate data: Ecological Indicators (in revision).
Products Completed in FY2012
- Homer, C.G., Meyer, D.K., Aldridge, C.L. and Schell, S.J., 2013, Detecting annual and seasonal changes in a sagebrush ecosystem with remote sensing derived continuous fields: Journal of Applied Remote Sensing, v. 7, no. 1, at http://remotesensing.spiedigitallibrary.org/data/Journals/APPRES/926148/JARS_7_1_073508.pdf.
Products Completed in FY2011
- Resampled (field observations) of permanent monitoring plots at 260 locations distributed across four QuickBird scenes.
- Trend analysis to detect change in sagebrush components across five years of sampling in permanent plots; trend analysis incorporated field-plot data, QuickBird imagery, and Landsat imagery.
- Further development of eight spatial models based on two QuickBird scenes for the five primary sagebrush components based on Landsat path 37/row 31 (southwestern Wyoming) for every other year, beginning with 2008 back to 1985, for use in trend analyses.
- Landsat change-vector analysis for the entire WLCI region to evaluate the amount of change in seven components of sagebrush habitat between 2006 and 2010.
- Homer, C.G., Aldridge, C.L., Meyer, D.K., and Schell, S.J., 2012, Multi-scale remote sensing sagebrush characterization with regression trees over Wyoming, USA -- Laying a foundation for monitoring: International Journal of Applied Earth Observation and GeoInformation, v. 14, p. 233-244, at http://www.sciencedirect.com/science/article/pii/S0303243411001358.
- Xian, G., Homer, C.G., and Aldridge, C.L., 2011, Assessing long-term variations in sagebrush habitat -- Characterization of spatial extents and distribution patterns using multi-temporal satellite remote sensing data: International Journal of Remote Sensing, v. 33, no. 7, p. 2034-2058.
- Xian, G., Homer, C.G., and Aldridge, C.L., 2012, Effects of land cover and regional climate variations on long-term spatiotemporal changes in sagebrush ecosystems: GIScience & Remote Sensing, v. 49, no. 3, p. 378-396.
Products Completed in FY2010
- Data from re-sampling permanent monitoring plots at 422 locations distributed across six QuickBird scenes.
- Data from sampling plots at 125 newly established permanent monitoring locations distributed across two additional QuickBird scenes.
- Updated coordinates for more than 400 permanently marked sites.
- Trend analysis to detect change in sagebrush components across four years of permanent plot sampling. Trend analysis incorporated field plot data, QuickBird imagery, and Landsat imagery.
- Analyses of change in vegetation components (and variability in cover) with environmental variables/ecosystem drivers (for example, precipitation and temperature) across the WLCI region, based on field sampling.
- Developed eight spatial models for sagebrush components based on two Quickbird scenes and for the five primary sagebrush components based on Landsat path 37/row 31 (southwestern Wyoming) for every other year, beginning with 2006 back to 1985, for use in trend analyses.
- Manier, Daniel J.; Aldridge, Cameron; Anderson, Patrick; Chong, Geneva; Homer, Collin; O'Donnell, Michael; and Schell, Spencer
(2011) "Land Use and Habitat Conditions Across the Southwestern Wyoming Sagebrush Steppe: Development Impacts,
Management Effectiveness and the Distribution of Invasive Plants," Natural Resources and Environmental Issues: Vol. 17, Article 4.
Available at: http://digitalcommons.usu.edu/nrei/vol17/iss1/4
