In 1960, soon after the establishment of HBEF, ecologist Gene Likens and geologist Noye Johnson, both from Dartmouth, joined the research team. In 1963, the group received a $60,000 grant from the National Science Foundation to study "Hydrological-Mineral Cycle Interaction in a Small Watershed". This study evolved into the series of longitudinal studies now referred to as the "Hubbard Brook Ecosystem Study", or HBES. The early ecosystem monitoring was aimed at studying the effects of forest management practices on water flow and quality. These data have been helpful as baselines for the increasingly sophisticated areas of ongoing research in the forest. HBES has spawned over 2000 scientific papers, perhaps most important a 1968 study that documented the widespread presence of "acid rain". HBRF was designated as a Long-Term Ecological Research (LTER) site in 1988 and has some of the longest on-going ecological datasets.