51. Feature Extraction Techniques for Measuring Piñon and Juniper Tree Cover and Density, and Comparison with Field-Based Management Surveys
- Author
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Matthew D. Madsen, Bruce A. Roundy, Daniel L. Zvirzdin, Bracken D. Davis, and Steven L. Petersen
- Subjects
Conservation of Natural Resources ,Global and Planetary Change ,Tree canopy ,Ecology ,biology ,Data Collection ,Forest management ,Land cover ,Woodland ,Pinus ,biology.organism_classification ,Pollution ,Tree (data structure) ,Aerial photography ,Juniperus ,Environmental science ,Cover (algebra) ,Juniper ,Remote sensing - Abstract
Western North America is experiencing a dra- matic expansion of pinon (Pinus spp.) and juniper (Juni- perus spp.) (P-J) trees into shrub-steppe communities. Feature extracted data acquired from remotely sensed imagery can help managers rapidly and accurately assess this land cover change in order to manage rangeland eco- systems at a landscape-scale. The objectives of this study were to: (1) develop an effective and efficient method for accurately quantifying P-J tree canopy cover and density directly from high resolution photographs and (2) compare feature-extracted data to typical in-situ datasets used by land managers. Tree cover was extracted from aerial-pho- tography using Feature Analyst. Tree density was calcu- lated as the sum of the total number of individual polygons (trees) within the tree cover output file after isolation using a negative buffer post-processing technique. Feature- extracted data were compared to ground reference mea- surements from Utah's Division of Wildlife Resources Range Trend Project (DWR-RTP). We found that the proposed feature-extraction techniques used for measuring cover and density were highly correlated to ground refer- ence and DWR-RTP datasets. Feature-extracted measure- ments of cover generally showed a near 1:1 relationship to these data, while tree density was underestimated; how- ever, after calibration for juvenile trees, a near 1:1 rela- tionship was realized. Feature-extraction techniques used in this study provide an efficient method for assessing important rangeland indicators, including: density, cover, and extent of P-J tree encroachment. Correlations found between field and feature-extracted data provide evidence to support extrapolation between the two approaches when assessing woodland encroachment. more...
- Published
- 2011
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