Near-real-time Herbaceous Annual Cover in the Sagebrush Ecosystem (June 19, 2017)

Dates

Publication Date: 2017-07-07
Time Period: 2017-06-19

Citation

Boyte, S.P., and Wylie, B.K., 2017, Near-real-time Herbaceous Annual Cover in the Sagebrush Ecosystem (June 19, 2017): U.S. Geological Survey data release, https://doi.org/10.5066/F7M32TNF.

Summary

This dataset provides a near-real-time estimate of 2017 herbaceous annual cover with an emphasis on annual grass (Boyte and Wylie. 2016. Near-real-time cheatrass percent cover in the Northern Great Basin, USA, 2015. Rangelands 38:278-284.) This estimate was based on remotely sensed enhanced Moderate Resolution Imaging Spectroradiometer (eMODIS) Normalized Difference Vegetation Index (NDVI) data gathered through June 19, 2017. This is the second iteration of an early estimate of herbaceous annual cover for 2017 over the same geographic area. The previous dataset used eMODIS NDVI data gathered through May 1 (https://doi.org/10.5066/F7445JZ9). The pixel values for this most recent estimate ranged from 0 to100% with an overall mean value [...]

Summary

This dataset provides a near-real-time estimate of 2017 herbaceous annual cover with an emphasis on annual grass (Boyte and Wylie. 2016. Near-real-time cheatrass percent cover in the Northern Great Basin, USA, 2015. Rangelands 38:278-284.) This estimate was based on remotely sensed enhanced Moderate Resolution Imaging Spectroradiometer (eMODIS) Normalized Difference Vegetation Index (NDVI) data gathered through June 19, 2017. This is the second iteration of an early estimate of herbaceous annual cover for 2017 over the same geographic area. The previous dataset used eMODIS NDVI data gathered through May 1 (https://doi.org/10.5066/F7445JZ9). The pixel values for this most recent estimate ranged from 0 to100% with an overall mean value of 7.02% and a standard deviation of +/-9.08. The model's test mean error rate (n = 1664), based on nine different randomizations, equaled 5.2% with a standard deviation of +/- 0.09. Overall statistics between the May and June datasets were similar. However, some individual pixel differences can be considerable and are attributed to changing conditions on the ground that are reflected in the satellite data. These changes can influence how the models relate the dependent variable to the independent variables. Both datasets were generated by integrating ground-truth measurements of annual herbaceous percent cover with 250-m spatial resolution eMODIS NDVI satellite derived data and geophysical variables into regression-tree software. The geographic coverage includes the Great Basin, the Snake River Plain, the state of Wyoming, and contiguous areas. We applied a mask to areas above 2250-m elevation because annual grasses are unlikely to exist at substantial cover above this threshold. To target likely sagebrush ecosystems, the mask also covered pixels classified as something other than shrub or grassland/herbaceous by the 2011 National Land Cover Dataset (NLCD). The model was not trained on any masked pixels. Cheatgrass (Bromus tectorum) is the most common annual grass in the study area. It grows from seed, usually in spring, matures quickly, produces seed, and dies. After dying, cheatgrass contributes fine fuels that facilitate fire ignition and spread throughout sagebrush ecosystems. These fires remove sagebrush stands. Increasing fire frequencies, land management practices, and development have all contributed to the fragmentation of the once expansive sagebrush ecosystems. These ecosystems are critical for water quality, reduced fire threats, and the survival of sagebrush-dependent wildlife.

Contacts

Point of Contact :: Stephen P. Boyte
Originator :: Stephen P. Boyte, Bruce K. Wylie
Metadata Contact :: Stephen P. Boyte
Distributor :: U.S. Geological Survey - ScienceBase
USGS Mission Area :: Land Resources
SDC Data Owner :: Earth Resources Observation and Science (EROS) Center

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2017nrt_JuneAnnHerbaceous_metadata_FGDC.xml Original FGDC Metadata	View	14.54 KB	application/fgdc+xml
2017_JuneAnnHerbaceous.jpg		24.49 MB	image/jpeg
2017nrt_JuneAnnHerbaceous.img		20.62 MB	application/unknown
2017nrt_JuneAnnHerbaceous.rrd		7.06 MB	application/unknown
2017nrt_JuneAnnHerbaceous.img.aux.xml		1.8 KB	application/xml
2017nrt_JuneAnnHerbaceous.img.lyr		25.5 KB	application/x-tika-msoffice

Purpose

These data were developed to provide land managers and researchers with near-real-time estimates of spatially explicit percent cover predictions of herbaceous annual vegetation cover in the study area. Appropriate use of the data should be defined by the user; however, this data comes with caveats. First, these estimates should be viewed as relative abundances. Second, each pixel in the dataset represent 250-meters and can include a geolocation error of up to 125 meters. Comparing this dataset to similar datasets with different spatial resolutions can lead to substantial differences between datasets.

Near-real-time Herbaceous Annual Cover in the Sagebrush Ecosystem (June 19, 2017)

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