Using Unmanned Helicopters to Assess Vegetation Cover in Sagebrush Steppe Ecosystems

Evaluating vegetation cover is an important factor in understanding the sustainability of many ecosystems. Remote sensing methods with sufficient accuracy could dramatically alter how biotic resources are monitored on both public and private lands. Idaho National Laboratory (INL), in conjunction with the University of Idaho, evaluated whether unmanned aerial vehicles (UAVs) are sufficiently accurate and more efficient than the point-frame field method for monitoring vegetative cover and bare ground in sagebrush steppe ecosystems. These values are of interest to land managers because typically there are limited natural resource scientists and funding for comprehensive ground evaluations. In this project, unmanned helicopters were used to collect still-frame imagery to determine vegetation cover during June and July 2005. The images were used to estimate percent cover for six vegetative cover classes (shrub, dead shrub, grass, forbs, litter, and bare ground). Field plots used to collect imagery and on-the-ground measurements were located on the INL site west of Idaho Falls, Idaho. Ocular assessments of digital imagery were performed using SamplePoint, and the results were compared with field measurements collected using a point-frame method. The helicopter imagery evaluation showed a high degree of agreement with field cover class values for grass, litter, and bare ground and reasonable agreement for dead shrubs. Shrub cover was often overestimated, and forbs were generally underestimated. The helicopter method took 45% less time than the field method. This study demonstrates that UAV technology provides a viable method for monitoring selective types of cover on rangelands and could save time and resources. Evaluar la cobertura vegetal es un importante factor para entender la sustentabilidad de muchos ecosistemas. Métodos de teledetección con suficiente precisión pueden considerablemente alterar la manera en como los recursos bióticos son monitoreados tanto en propiedad privada y pública. El laboratorio Nacional de Idaho (INL), en conjunto con la universidad de Idaho, evaluaron si vehículos aéreos no tripulados (UAVs) son suficientemente precisos y más eficientes que los métodos de campo basados en punto de referencia para monitorear la cobertura de las vegetación y el suelo desnudo en los ecosistemas de pastizales de Artemisia. Estas evaluaciones son de interés para los manejadores de tierra ya que normalmente hay pocos científicos dedicados al estudio de l