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United States Department of Agriculture

Agricultural Research Service

Research Project: RANGELAND RESTORATION AND MANAGEMENT

Location: Range and Meadow Forage Management Research

Title: An object-based image analysis of pinyon and juniper woodlands treated to reduce fuels

Authors
item Hulet, April
item Roundy, Bruce -
item Petersen, Steven -
item Jensen, Ryan -
item Bunting, Stephen -

Submitted to: Environmental Management
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 23, 2013
Publication Date: January 9, 2014
Repository URL: http://handle.nal.usda.gov/10113/58792
Citation: Hulet, A., Roundy, B.A., Petersen, S.L., Jensen, R.R., Bunting, S.C. 2014. An object-based image analysis of pinyon and juniper woodlands treated to reduce fuels. Environmental Management. 53:660-671.

Interpretive Summary: Mechanical and prescribed fire treatments are commonly used to reduce fuel loads and maintain or restore sagebrush steppe rangelands across the Great Basin where pinyon and juniper trees are encroaching and infilling. Our objective was to evaluate the relationship between object-based image analysis (OBIA) cover estimates (extracted from high-spatial resolution color infrared imagery) with ground measured cover in woodlands where fuels were reduced. Differences between mean cover estimates using OBIA and ground-measurements were not consistently higher or lower for any land cover class (burned, cut, and masticated trees, shrubs, herbaceous vegetation, litter, and bare ground) and when evaluated for individual sites, were within ± 5% of each other. Although cover assessments from OBIA differed somewhat from ground measurements, they are sufficiently accurate to evaluate treatment success, provide data for planning and designing future fuel-reduction treatments, and for assessing the spatial distribution of horizontal fuel structure following fuel-reduction treatments.

Technical Abstract: Mechanical and prescribed fire treatments are commonly used to reduce fuel loads and maintain or restore sagebrush steppe rangelands across the Great Basin where pinyon (Pinus) and juniper (Juniperus) trees are encroaching and infilling. Geospatial technologies, particularly remote sensing, could potentially be used in these ecosystems to 1) evaluate the longevity of fuel reduction treatments, 2) provide data for planning and designing future fuel-reduction treatments, and 3) assess the spatial distribution of horizontal fuel structure following fuel-reduction treatments. High-spatial resolution color-infrared imagery (0.06-m pixels) was acquired for pinyon and juniper woodlands plots where fuels were reduced by either prescribed fire, tree cutting, or mastication at five sites in Oregon, California, Nevada, and Utah. Imagery was taken with a Vexcel UltraCam X digital camera in June 2009. Within each treatment plot, ground cover was measured as part of the Sagebrush Steppe Treatment Evaluation Project. Trimble eCognition Developer was used to classify land cover classes using object-based image analysis (OBIA) techniques. Differences between mean cover estimates using OBIA and ground-measurements were not consistently higher or lower for any land cover class and when evaluated for individual sites, were within ± 5% of each other. The overall accuracy and the Kappa statistic for classified thematic maps for each treatment were: prescribed burn 85% and 0.81; cut and fell 82% and 0.77, and mastication 84% and 0.80. Although cover assessments from OBIA differed somewhat from ground measurements, they are sufficiently accurate to evaluate treatment success and for supporting a broad range of management concerns.

Last Modified: 8/1/2014
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