Satellites help plant control

Kearny County, Kan., officials are using commercial satellite imagery to help manage the problem posed by the Tamarisk plant, an invasive species that depletes local water supplies, thereby threatening fire prevention and environmental preservation. One factor limiting the ability to minimize the plant's impact is the difficulty of accurately mapping its distribution and abundance, said Shannon McCormick, Kearny County commissioner. This prompted a search for a quick, cost-effective and repeatable method for surveying the area.

County officials hooked up with Colorado-based Native Communities Development Corp. (NCDC), a specialist at this sort of work. The company used DigitalGlobe's QuickBird satellite images to assess the Tamarisk threat along 32 miles of the Arkansas River.

NCDC officials use proprietary algorithms that allow them to separate the Tamarisk's spectral signature from those of other plants around it, said Chuck Herring, director of marketing communications at DigitalGlobe. The data then went through other analysis software to create a detailed inventory for developing control plans for the plant.

"This was kind of a test bed that turned into a full scale project," Herring said. "The issue of invasive species is a major problem out in the West, so we are looking to see of this approach could be a useful tool to help solve it."

The particular problem with Tamarisk, also known as salt cedar, is that it consumes water at about twice the rate as indigenous plants, lowering water tables and drying up resources. In the 874 acres initially surveyed by NCDC, Tamarisk consumes about 682 millions gallons a year, equivalent to what $495,000 worth of a corn crop would use.

Robinson is a freelance journalist based in Portland, Ore. He can be reached at hullite@mindspring.com.