A new method of monitoring for changes in rangeland conditions is being developed by USDA Agricultural Research Service (ARS) scientists that will allow better management of those areas. In its early stages the Very Large Scale Aerial (VLSA) imagery programme has been very helpful in finding changing conditions, such as increasing leafy spurge populations in some areas.
ARS rangeland specialist Terry Booth has been instrumental in developing the programme. He has found it to be a good way to sample vast areas of the western United States, especially when detecting invasive weeds like leafy spurge.
Booth is stationed at the ARS Rangeland Resources Research Unit in Cheyenne, Wyo., and received funding and technical assistance from the Department of Interior’s Bureau of Land Management (BLM).
“We recommend that it be used with ground-based methods for early detection of invasive species that might threaten native plant populations,” Booth said.
Aerial photography reduces the number of ground surveys needed, he said. “But before you can analyse aerial photographs of, say, plant communities, you need a lot of experience identifying the plant communities on the ground.”
So far, he has done aerial surveys in Idaho, Colorado, Nevada, New Mexico, North Dakota, South Dakota, Oklahoma and Wyoming. Those surveys have looked at a variety of vegetation, including invasive species and native trees, grasslands and shrublands. Sites surveyed have ranged from gas pipeline rights-of-way to riverbanks, in addition to regular rangeland areas.
His research efforts are a part of a nationwide programme where ARS scientists are using aerial photography to monitor a variety of lands with digital camera and sensors. These cameras and sensors are flown aboard a wide variety of aircraft – from regular small passenger planes to light sport airplanes to unmanned aircraft.
In the past, satellite imagery was used extensively for this purpose, but satellites can’t provide the resolution needed by BLM assessments of millions of acres of federally owned land. UAS allow operators to survey line-of-sight areas repeatedly or immediately after a major rainstorm or forest fire. When photographs must be obtained in conditions that would put a pilot at risk, UAS have the advantage over manned airplanes and they can acquire imagery at very high resolution.
A group of ARS scientists and Andrea Laliberte, a New Mexico State University researcher, are studying the use of a UAS that cruises 700 feet above the Earth, collecting digital photographs of rangeland areas that are so large they are difficult to cover in ground-based surveys. The aircraft weighs 20 pounds, has a 6-foot wingspan and is launched from a catapult.
The goal of using aerial imagery, according to Laliberte, is to measure rangeland vegetation cover as well as collect enough information about landscape patterns, so determinations can be made on which areas merit closer ground level surveys.
Source: Farm & Ranch Guide