The Critical Zone is the zone on Earth where rocks meet life: as such, this zone supports the functioning of human society. Due to ongoing anthropogenic activity, the health of this Zone, including the hydrosphere, biosphere, lithosphere and atmosphere, is now under stress. Soils integrate and record the chemical, biological, and physical processes occurring in the Critical Zone, and as such provide a long-term history of change.
To understand long-term and recent change in the Critical Zone, a global and interdisciplinary Critical Zone community has formed to collect, track, and disseminate data on Critical Zone processes that are driven by changes in important environmental variables. This community continues to grow as groundwater chemists, soil chemists, geomorphologists, ecologists, microbiologists, and others seek to understand the coupled processes in the Critical Zone.
To guide and advance future research programs in Critical Zone science, the proponents plan to organize a workshop, ?The Critical Zone: A Workshop on the Biological Aspects of Weathering,? to be held in October 2009 in Washington, D.C. Approximately 20 to 25 leading scientists in the fields of geosciences, soil sciences, ecology and microbiology will participate. This cross-disciplinary workshop will be organized by Susan L. Brantley, Pennsylvania State University, and Patrick Megonigal, Smithsonian Environmental Research Center, and will be held at the Smithsonian Institute?s National Museum of Natural History. The goal of the workshop will be to articulate a research agenda for the biological aspects of weathering science for the next 10 years. The discussions will lead to a publication on the topic that will lay out up to 10 important research questions.
Broader Impacts. In this proposal, we ask NSF to subsidize the costs of the meeting. Workshop participants will derive from university and government organizations and will derive from a variety of disciplines. The goals of the workshop will have broad impact because the workshop will: ? Foster multidisciplinary collaboration among Critical Zone scientists ? Identify new approaches to Critical Zone science ? Identify research areas that are currently underfunded and that lie between geosciences and biological sciences ? Develop research priorities for weathering science ? Articulate a 10-year research agenda for the interface of geochemistry-biology as it pertains to Critical Zone science ? Produce one publication highlighting future research priorities
Critical Zone Science: A Workshop on the Biological Aspects of Weathering; October 3-5, 2009, Washington, DC Funding from the National Science Foundation made it possible for 29 scientists from around the country and the U.K. to attend a workshop, "Frontiers in Exploration of the Critical Zone III: The Geobiology of Weathering and Erosion," held October 5-7, 2009, at the Smithsonian Institution National Museum of Natural History. Susan Brantley (The Pennsylvania State University), Patrick Megonigal (Smithsonian Environmental Research Center) and Frederick Scatena (University of Pennsylvania) co-chaired the workshop. Critical zone research investigates the chemical, physical, and biological processes that modulate the Earth's surface. The primary goal of the workshop was to identify the important problems in Critical Zone science and produce a publication that discussed the critical topics that should be investigated within a 10-year timeframe. While most workshop participants were affiliated with colleges and universities, two were from government agencies (USGS and USDA Forest Service). The scientific disciplines represented included soil science, environmental and architectural engineering, geosciences, pedology and environmental science. The participants included a mix of early career scientists and more established scientists. During the workshop, scientists discussed key research areas that needed to be addressed in the coming years. Discussions and break-out sessions resulted in the creation of specific, testable hypotheses for further investigation. It is our hope that these hypotheses will stimulate important research in weathering, erosion, and biology. The 12 hypotheses that need to be tested to improve understanding of the critical zone are as follows: (1) Solar-to-chemical conversion of energy by plants regulates flows of carbon, water, and nutrients through plant-microbe soil networks, thereby controlling the location and extent of biological weathering. (2) Biological stoichiometry drives changes in mineral stoichiometry and distribution through weathering. (3) On landscapes experiencing little erosion, biology drives weathering during initial succession, whereas weathering drives biology over the long term.(4) In eroding landscapes, weathering-front advance at depth is coupled to surface denudation via biotic processes. (5) Biology shapes the topography of the Critical Zone. (6) The impact of climate forcing on denudation rates in natural systems can be predicted from models incorporating biogeochemical reaction rates and geomorphological transport laws. (7) Rising global temperatures will increase carbon losses from the Critical Zone. (8) Rising atmospheric PCO2 will increase rates and extents of mineral weathering in soils. (9) Riverine solute fluxes will respond to changes in climate primarily due to changes in water fluxes and secondarily through changes in biologically mediated weathering. (10) Land use change will impact Critical Zone processes and exports more than climate change. (11) In many severely altered settings, restoration of hydrological processes is possible in decades or less, whereas restoration of biodiversity and biogeochemical processes requires longer timescales. (12) Biogeochemical properties impart thresholds or tipping points beyond which rapid and irreversible losses of ecosystem health, function, and services can occur. These hypotheses are further explained in the published document resulting from these discussions: "Twelve testable hypotheses on the geobiology of weathering," appearing in the March 2011 issue of Geobiology.
