Working on scientific questions at the interface between plant functional biology, hydrology, climatology, ecosystem science and the Earth sciences has emerged in recent years to define a new and growing area of interdisciplinary research in the Earth’s “critical zone” (earth to atmosphere). As it enters its 6th year, the network of NSF-sponsored Critical Zone Observatories (CZO’s) is making significant strides in bringing the physical and biological sciences together to make innovative observations of Earth surface processes never made before. Our labs role in the CZO research agenda is to plug in the important plant functional biology and stable isotope biogeochemistry to aid in addressing a wide range of questions at a variety of scales (micro to macro). In this context we have long believed that plants can exert a marked impact on climate at a range of scales, yet evidence of such an impact has been limited. Through a campaign of measurements and modeling we have begun to show that plants, in a range of ways, are indeed having a marked influence on environmental conditions at scales from a single tree crown to entire regions of Earth. See: The Eel River CZO website