Introduction to Critical Zone science and CZ Observatories (CZO) Dr. Tim White Earth and Environmental Systems Institute The Pennsylvania State University

Critical Zone: Term published by the U.S. National Research Council in 2001 BROES report = Thin veneer at Earth’s surface spanning from the top of vegetation canopy through soil to deep in the subsurface where fresh groundwater circulates. = Critical Zone –v- critical zones?

Soil exists at the “ heart ” of the Critical Zone Important for: - agriculture - water filtration - C sequestration - biodiversity But degraded by humanity.

Societal relevance: The zone within which most terrestrial life exists and depends on. Ongoing climate and land use changes to the zone may stress terrestrial life including humanity – thus a better understanding of CZ processes and function may aid adaptation to change.

* Pollination * Fulfillment of cultural, spiritual/intellectual needs * Regulation of climate * Insect pest control * Maintenance and provision of genetic resources * Maintenance and regeneration of habitat * Provision of shade and shelter * Prevention of soil erosion * Maintenance of soil fertility * Maintenance of soil health * Maintenance of healthy waterways * Water filtration * Regulation of river flows and groundwater levels * Waste absorption and breakdown Critical Zone Services If we allow natural assets to decline, so do the benefits. But if we care for and maintain natural assets, we will reap greater returns.

PopulationWorld GDPGDP per Capita HungerEnergy Demand CO 2 Emissions Food Demand Water Demand = Source: National Academy Press, Our Common Journey (1999) Global Trajectories of Human Forcing of the Environment (indexed to 1995)

A primary goal of the CZOs is to gather interdisciplinary scientific information from diverse landscapes that can be more broadly applied, or scaled up, to understand and manage the effects of ongoing land-use and climate change at regional, continental and global scales.

State of CZ Science: Ten CZOs represent an array of geologic, climatologic and ecologic settings in which a variety of Critical Zone processes can be studied from the vegetation canopy into bedrock. ER RC IML CH - SC

The sites promote site-specific research and education activities and are beginning to create community among a diverse group of CZ scientists (CUAHSI, geomorphology, CZEN, geobiology…. ER RC IML CH - SC

To the CZ community, the sites represent the initial steps toward building a network that can attract a diverse group of Earth scientists to advance CZ science by answering questions like: How has the CZ changed and how will it change in the future? ER RC IML CH - SC

Critical Zone science and Observatories (CZOs) evolved from the recognition that many similar scientific questions were being asked by diverse groups of Earth surface scientists who did not typically collaborate. For example…..

Societal and Scientific Questions from the Water and Environmental Research Systems (WATERS) Network Science Plan: (1)How are human pressures and climate trends changing the water cycle? (2) How will fresh water availability change and how can we better predict the change? (3) How can we predict and better manage water availability and quality for future generations and ecosystems?

Geobiological hypotheses developed during Geobiology of Weathering and Erosion meeting, 2009 (1)How does biology shape the topography of the CZ? (2) How will increasing global temperatures change carbon losses and chemical weathering fluxes from the CZ? (3) Will land use change impact CZ processes and exports compared to climate change?

Fundamental Geomorphologic considerations in CZ science 1)What controls the depth to bedrock? to regolith? the land surface itself? 2)How do biological agents affect the CZ? 3)How do the processes (and rates) of processes that govern landscape evolution change as climate changes?

Nutrients Chemistry of Water Atmosphere Landform Evolution What processes control fluxes of carbon, particulates, and reactive gases over different timescales? How do biogeochemical processes govern long- term sustainability of water and soil resources? How do processes that nourish ecosystems change over human and geologic time scales? How do variations in and perturbation to chemical and physical weathering processes impact the Critical Zone? Four Driving Questions of CZ Science

CZOs bring diverse interdisciplinary communities together to build cross-science alliances to answer these complex interdisciplinary questions. But…… How?

CHALLENGES: - Critical Zone is a complex system(s) - CZ is global in extent, therefore requires international cooperation and funding. -Deeply interdisciplinary, requires new cadre of scientists

Network Approach To explore one environmental variable with other variables constant To compare data measured in the same way at multiple sites To understand broad patterns of behavior To create community among scientists and generate interdisciplinary understanding

Soil formation, or pedogenesis, is controlled by five variables in nature, the so-called state factors: 1. parent material 2. climate 3. topography 4. biota 5. time 6. humans

Climate Topography Biology TimeTime Lithology Environmental gradients Disturbance

CZO Network (2013): criticalzone.orgcriticalzone.org ER RC IML CH - SC SS Southern Sierra CZO (California)BC Boulder Creek CZO (Colorado) SH Susquehanna-Shale Hills CZO (Pennsylvania) Christina River Basin CZO (Pennsylvania/Delaware) Jemez River Basin – Sta. Catalina CZO (New Mexico/Arizona)LM-Luquillo CZO (Puerto Rico) ER Eel River CZO (California)RC Reynolds Creek CZO (Idaho) IML Intensively Managed Landscapes CZO (Illinois/Iowa)CH Calhoun CZO (South Carolina)

CZO Timeline NRC report, 2001 NFS funds 3 CZO’s, 2007 (SS,BC,SH) Elements special section, 2007 VZJ special section, 2011 DHA funds 4 CZO’s, 2008 (TERENO network) NFS funds 3 CZO’s, 2009 (J-C,CR, LQ) EU funds 4 CZO’s, 2009 (CH,AU,GR,CZ) NFS funds 4 CZO’s, 2014 (ER,RC,IML,CH) All Hands Meeting, B2, 2012 All Hands Meeting, UCM, 2014