Jason Siemion Gregory B. Lawrence M. Alisa Mast Michael R. McHale 2014 Monitoring the environment by making repeated measurements through time is essential to evaluate and track the health of ecosystems (fig. 1). Long-term datasets produced by such monitoring are indispensable for evaluating the effectiveness of environmental legislation and for designing mitigation strategies to address environmental changes in an era when human activities are altering the environment locally and globally. application/pdf 10.3133/fs20143002 en U.S. Geological Survey Long-term soil monitoring at U.S. Geological Survey reference watersheds reports