ABSTRACT

The critical zone is a thin layer at the Earth?s surface where rock, soil, water, air, and living organisms interact. The critical zone supports life on Earth. In the western United States, the critical zone is sensitive to changes in the environment, such as fires or droughts. This project studies how processes in the critical zone respond to changes in the environment. Data are collected from five watersheds in Colorado and California. The project links the fields of water science, forest ecology, rock chemistry and soil chemistry. The project connects the way water moves and is stored in the ground to how trees grow and to how soil and rocks change. Studying these interactions is important to understanding how Earth will respond to future changes in climate. Researchers from six universities work together. Students are trained in several areas of Earth science. Educational materials are developed for all grade levels including K-12 and college.

The Earth?s critical zone is defined as the upper layer of the Earth?s surface, from bedrock to the tree canopy, and is dependent upon the co-evolution of Earth system processes including interactions among climate, hydrology, biogeochemistry, and geology. Despite the fundamental importance of water in critical zone processes, there is not widespread understanding of the relations between how water is stored in the critical zone and how it affects key processes, or how global change drivers, such as climate shifts and disturbance, will modify these interactions. The goals of this critical zone network cluster are to 1) advance understanding of the interactions among water storage, critical zone processes, and water provisioning in the complex physiography of western United States montane ecosystems; 2) explore how water storage and critical zone processes will be altered under global change drivers; and 3) create educational opportunities and resources about the critical zone that are accessible to a diverse student population, including K-12 to postgraduates. The network cluster consists of five research catchments with differing critical zone structure and water storage capacity where the research team collects a common suite of field measurements and conducts coordinated modeling activities. Field measurements include monitoring of hydrologic and biogeochemical fluxes, as well as, surveys of near-surface geophysical properties and forest structure and dynamics. The modeling platforms for this project include: 1) integrated hydrologic models that can fully resolve overland, unsaturated, and saturated flow to full quantify the roles of climate, vegetation, subsurface structure, and topography on hydrologic partitioning, 2) reactive transport models that fully resolve biogeochemical reaction networks with flexible implementation of reaction kinetics and thermodynamics to estimate weathering and biogeochemical reaction rates and fluxes at the catchment scale, and 3) an ecohydrology model that couples hydrologic processes with dynamics of vegetation and ecosystem carbon and nutrient cycles and ecosystem disturbance including vegetation mortality and fire. The broader impacts of this project include 1) research experiences and training of students at multiple education levels, including students in middle school, undergraduate institutions, and graduate school; and 2) improving public science literacy of critical zone processes through the creation of interactive virtual reality video installations. In addition, this network cluster maintains and expands research infrastructure to provide a facility for the Earth science community. This project is jointly funded by the Critical Zone Collaborative Network, the Hydrologic Sciences, and the Education and Human Resources programs in the Division of Earth Sciences.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

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