Employing spatial information technologies to monitor biological control of saltcedar in West Texas

Abstract

The saltcedar leaf beetle (Diorhadha spp.) has shown promise as a biocontrol agent for saltcedar (Tamarix spp.) invasions in the USA. In Texas, natural resource managers need assistance in monitoring biological control of invasive saltcedars. This study describes application of a medium-format, digital camera acquiring natural colour imagery and global positioning system (GPS) and geographic information system (GIS) technologies to check biological control of saltcedar in west Texas. On 8 July and 8 September 2011, natural colour airborne digital imagery was collected along a 155.8 km transect covering portions of Presidio and Brewster counties of Texas. The camera was tethered to a GPS receiver that geotagged each image and saved the coordinates to a key-hole marked up language file that was viewable on Google Earth. Saltcedar trees exhibiting severe feeding damage and those that were totally defoliated were easily identified in the imagery. The former appeared in orange to brown colour tones; the latter exhibited grey colour tones. Point distribution maps showing locations of saltcedar trees exhibiting feeding damage were developed from GPS information in the GIS. Coordinate points on the map were linked to the corresponding image, permitting the user to have quick access to view imagery. The results of this study show a practical method for monitoring biological control of saltcedar.

Keywords:

• remote sensing
• saltcedar leaf beetle
• geographic information system
• global positioning system
• Hasselblad

Acknowledgements

The author thanks Dr Jack DeLoach, Dr Chris Ritzi, Juan Ramos, Isabel Cavazos, Fred Gomez, Michael Ohlinger, James Tracy, Ann Marie Hilshcer, and Jim Forward for their assistance in this study.

Notes

This project was funded by USDA-ARS; mention of trade names or commercial products in this publication is solely for the purpose of providing specific information and does not imply recommendation or endorsement by the USDA.