Crustal Imaging and Characterization Team
Task Contact: Trude King
The objectives of this task include:
ASTER data from multiple dates following disturbance events will be used to track changes in soil and vegetation cover across the disturbed landscape. These changes will be related to field-based measures of rainfall, erosion, and vegetation in order to better understand the impact of soil chemical and physical characteristics on post-disturbance ecosystem processes. Work on the calibration of ASTER data will continue using data from other sites to assess the viability of generating an empirical correction factor to convert radiance data to apparent surface reflectance. Software documentation of these programs will continue to be developed and released as open-file publications. A peerreviewed journal article on the application of ASTER to tracking changes in post-fire surface cover will be prepared for submission to Photogrammetric Engineering and Remote Sensing in August 2007.
Remote sensing data for disturbed areas were analyzed to determine the spectral signatures of vegetation and soils following disturbance. Two disturbance processes were examined this year: wildland fire and invasion by exotic plant species. Both processes rapidly impact the landscape and cause dramatic changes to surface materials.
Imaging spectroscopy data collected using the AVIRIS sensor following the Cerro Grande fire in Los Alamos, NM, were examined to characterize the post-fire surface in terms of vegetation, mineral and ash/charcoal cover. These characterizations derived from AVIRIS show that the spectral signature of ash/charcoal can be detected. In areas of high burn severity compared to moderate and low burn severity, more pixels are found to have spectral signatures related to minerals (iron-bearing and clay-bearing minerals) and ash/charcoal, and fewer pixels are found having spectral signatures caused by vegetation. Results from this research were presented at the Geological Society of America 2002 Annual Meeting, Denver CO, October 27-30, 2002. Research is continuing to analyze the distributions of green and dry vegetation, ash/charcoal, and minerals in relation to burn severity maps derived by the U.S. Forest Service.
New procedures have been developed to analyze LIDAR remote sensing data. LIDAR data over an area disturbed by wildland fire has been analyzed to detect changes in vegetation canopy morphology. The LIDAR-derived characterizations of vegetation structure are being examined in relation to AVIRIS-derived characteristics of plant biochemistry. The synthesis of these different types of remote sensing data is being examined to develop integrated methods to link changes in vegetation to disturbances caused by complicated environmental and anthropogenic factors such as underlying lithology and drainage from mined areas.
Data from airborne and satellite-borne remote sensing instruments have been collected and processed to examine the disturbance caused by invasive plant species. Data from AVIRIS, CASI, Landsat TM, EO-1 Hyperion and ALI are being analyzed to determine the costs and benefits of the different technologies in detecting the spread of the invasive plants. This work is being conducted in collaboration with other USGS disciplines and the Department of Agriculture. Infestations of the invasive plant leafy spurge have been identified using data from these sensors.
Remote sensing data were analyzed to examine the relationships between vegetation and soils and bedrock geology. A new method to discriminate between dry vegetation materials in pixels of hyperspectral data was developed. This method was applied to an area that had been burned by a wildfire in order to map dry conifers that were killed by the heat of the fire, but not consumed by the flames, and to delineate areas where dry straw matting was placed on the surface to control erosion. Results from this research were presented at the USGS GIS 2004 Meeting, Denver CO. A spatial analysis was conducted on maps of surface minerals and vegetation composition in conjunction with digital forms of bedrock geology maps. The results from this analysis show that the presence of cheatgrass, an invasive, cool season grass, is significantly correlated with alluvium material. The link between carbonate and an early season grass, cheatgrass, was examined. However, the coarse resolution of the hyperspectal remote sensing data (17 m pixel size) prevented the detection of carbonate signatures in areas covered by cheatgrass. These results have prompted additional studies of field spectra and low altitude hyperspectral remote sensing data (3.3 m pixel size) that will likely be able to detect minerals in areas of sparse grass cover.
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Mineral Resources |
Eastern / Central / Western / Alaska / Minerals Information |
| Crustal Imaging & Characterization / Spatial Data |
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U.S. Geological Survey
URL: http://crustal.usgs.gov
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