Object-based high-resolution classification of conifers in sagebrush ecosystems of the Great Basin
Summary
The distribution and abundance of conifers in sagebrush (Artemisia spp.) ecosystems of the Great Basin in the Western United States has increased substantially since the late 1800s. Encroachment of these trees can also present significant threats to populations of sagebrush obligate species, such as greater sage-grouse (Centrocercus urophasianus). Accordingly, baseline tools are needed to allow better understanding of factors influencing conifer encroachment into sagebrush ecosystems. Such tools also help facilitate informed management decisions aimed addressing the threats to populations of greater sage-grouse. To meet this need, WERC scientists have developed a suite of spatial products derived from high resolution mapping of conifers [...]
Summary
The distribution and abundance of conifers in sagebrush (Artemisia spp.) ecosystems of the Great Basin in the Western United States has increased substantially since the late 1800s. Encroachment of these trees can also present significant threats to populations of sagebrush obligate species, such as greater sage-grouse (Centrocercus urophasianus). Accordingly, baseline tools are needed to allow better understanding of factors influencing conifer encroachment into sagebrush ecosystems. Such tools also help facilitate informed management decisions aimed addressing the threats to populations of greater sage-grouse.
To meet this need, WERC scientists have developed a suite of spatial products derived from high resolution mapping of conifers (namely, singleleaf pinyon (Pinus monophylla), Utah juniper (Juniperus osteosperma), and western juniper (Juniperus occidentalis)) within: 1) the geographic range of greater sage-grouse in Nevada and portions northeastern California; and 2) the Bi-State Distinct Population Segment of greater sage-grouse at the extreme southwestern extent of the species range along the border of California and central Nevada.
Individual conifer trees were mapped at a 1x 1 meter resolution across the extent of all Nevada Department of Wildlife Sage-grouse Population Management Units plus a 10 km buffer. National Agriculture Imagery Program digital orthophoto quads (DOQQs) were used as the reference imagery, and object-based image analysis (using with Feature Analyst software) was used classify conifer features across study extents. This method relies on machine learning algorithms that extract features from imagery based on their spectral and spatial signatures. Conifers in 6,932 DOQQs were classified, and outputs tested for errors of omission and commission using stratified random sampling. Results of the random sampling were used to populate a confusion matrix and calculate the overall map accuracy of 84.3 percent for Nevada and northeastern California. The same method was used to calculate an overall accuracy of 87.0 percent for the Bi-State.
The pages that follow provide 4 sets of products derived from this mapping process across the entirety of both mapping extents. They include: (1) shapefiles representing accuracy results linked to distinct mapping subunits; (2) binary rasters representing conifer presence or absence at a 1 x 1 meter resolution; (3) a 30 x 30 meter resolution raster representing the continuous percentage of conifer canopy cover (0 – 100%) within each cell; and (4) 1 x 1 meter resolution canopy cover classification rasters derived from a 50 meter radius moving window analysis. The latter two products can be reclassified into user-specified bins to meet different management or study objectives. These products complement, and in some cases improve upon, existing conifer maps in the western United States, and will help facilitate sage-grouse habitat management and sagebrush ecosystem restoration.
The methods used to derive these products are explained in greater detail within the following publication: Coates, P.S., Gustafson, K.B., Roth, C.L., Chenaille, M.P., Ricca, M.A., Mauch, Kimberly, Sanchez-Chopitea, Erika, Kroger, T.J., Perry, W.M., and Casazza, M.L., 2017, Using object-based image analysis to conduct high-resolution conifer extraction at regional spatial scales: U.S. Geological Survey Open-File Report 2017-1093, 40 p., https://doi.org/10.3133/ofr20171093.
Note that the products derived for the Bi-State have yet to undergo final modifications to correct for hard seamline transitions. Updates will be posted soon.
Click on title to download individual files attached to this item.
Conifer_sagebrush_ecosystem.JPG ““Conifers in sagebrush ecosystem, northeastern NV. Photographer: Steve Hanser””
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Purpose
These data were created to provide land and wildlife managers with an additional resource to aid in conservation planning for sagebrush ecosystems within the geographic range greater sage-grouse across Nevada, portions of northeastern Californian, and the Bi-State Distinct Population Segment.
Rights
The authors of these data require that data users contact them regarding intended use and to assist with understanding limitations and interpretation. Unless otherwise stated, all data, metadata and related materials are considered to satisfy the quality standards relative to the purpose for which the data were collected. Although these data and associated metadata have been reviewed for accuracy and completeness and approved for release by the U.S. Geological Survey (USGS), no warranty expressed or implied is made regarding the display or utility of the data on any other system or for general or scientific purposes, nor shall the act of distribution constitute any such warranty. Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government.
Preview Image
“Conifers in sagebrush ecosystem, northeastern NV. Photographer: Steve Hanser”