The Critical Zone (CZ) is defined as the permeable layer from the top of the vegetation canopy to the bottom of freely circulating groundwater where rock, soil, water, air and life meet. The study of the CZ is motivated by an overall lack of understanding of the coupled physical, chemical, and biological processes in this zone at differing spatial and temporal scales. Critical Zone Observatories (CZOs), supported by the U.S. National Science Foundation’s Geosciences Directorate, are natural laboratories that aim to provide infrastructure, data and models to gain understanding of the evolution and function of the CZ from grain-to-watershed scales. The nine U.S. observatories span a range of climatic, ecologic, geologic, and physiographic environments from California to Puerto Rico, working on site-specific hypotheses and network-scale goals. CZO research infrastructure allows for teams of cross-disciplinary scientists at each site to further CZ science using field and theoretical approaches, education and outreach, and cross-CZO science.
Cross-CZO science emerges from a set of common CZ science questions and hypotheses focused on CZ structure and evolution, event-based and continuous fluxes across CZ interfaces, and changes in storage of major CZ reservoirs at the catchment scale. CZO research seeks to understand coupled processes across all timescales using quantitative models parameterized from observations of meteorological variables, streams, and groundwater, and sampling and analyzing landforms, bedrock, soils, and ecosystems. Each observatory strives to apply common infrastructure, protocols and measurements that help quantify the composition and fluxes of energy, water, solutes, sediments, energy, and mass across boundaries of the CZ system through both space and time. This type of approach enables researchers to access and integrate data in a way that allows for the isolation of environmental variables and comparison of processes and responses across environmental gradients. There is opportunity to foster cross-collaborations with existing research infrastructure (i.e. LTER, NEON, international CZOs) to promote cross-site science and expand upon geologic, climatic, ecological, land use and hydrologic gradients required to understand the CZ.
Sharkey, S. and White, T. (2017): Fostering Collaboration Across the US Critical Zone Observatories Network. 2017 American Geophysical Union Fall Meeting, New Orleans, LA, 11-15 Dec .
This Paper/Book acknowledges NSF CZO grant support.