Designing a network of critical zone observatories to explore the living skin of the terrestrial Earth
Abstract
The critical zone (CZ), the dynamic living skin of the Earth, extends from the top
of the vegetative canopy through the soil and down to fresh bedrock and the bottom
of the groundwater. All humans live in and depend on the CZ. This zone has three co-evolving
surfaces: the top of the vegetative canopy, the ground surface, and a deep subsurface
below which Earth's materials are unweathered. The network of nine CZ observatories
supported by the US National Science Foundation has made advances in three broad areas
of CZ research relating to the co-evolving surfaces. First, monitoring has revealed
how natural and anthropogenic inputs at the vegetation canopy and ground surface cause
subsurface responses in water, regolith structure, minerals, and biotic activity to
considerable depths. This response, in turn, impacts aboveground biota and climate.
Second, drilling and geophysical imaging now reveal how the deep subsurface of the
CZ varies across landscapes, which in turn influences aboveground ecosystems. Third,
several new mechanistic models now provide quantitative predictions of the spatial
structure of the subsurface of the CZ.<br>Many countries fund critical zone observatories
(CZOs) to measure the fluxes of solutes, water, energy, gases, and sediments in the
CZ and some relate these observations to the histories of those fluxes recorded in
landforms, biota, soils, sediments, and rocks. Each US observatory has succeeded in
(i) synthesizing research across disciplines into convergent approaches; (ii) providing
long-term measurements to compare across sites; (iii) testing and developing models;
(iv) collecting and measuring baseline data for comparison to catastrophic events;
(v) stimulating new process-based hypotheses; (vi) catalyzing development of new techniques
and instrumentation; (vii) informing the public about the CZ; (viii) mentoring students
and teaching about emerging multidisciplinary CZ science; and (ix) discovering new
insights about the CZ. Many of these activities can only be accomplished with observatories.
Here we review the CZO enterprise in the United States and identify how such observatories
could operate in the future as a network designed to generate critical scientific
insights. Specifically, we recognize the need for the network to study network-level
questions, expand the environments under investigation, accommodate both hypothesis
testing and monitoring, and involve more stakeholders. We propose a driving question
for future CZ science and a <q>hubs-and-campaigns</q> model to address that question
and target the CZ as one unit. Only with such integrative efforts will we learn to
steward the life-sustaining critical zone now and into the future.
Type
Journal articleSubject
Science & TechnologyPhysical Sciences
Geography, Physical
Geosciences, Multidisciplinary
Physical Geography
Geology
INTENSIVELY MANAGED LANDSCAPES
COLORADO FRONT RANGE
SOIL PROCESSES
CLIMATE-CHANGE
NEW-MEXICO
FOREST
WATER
VARIABILITY
CATCHMENT
EVOLUTION
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https://hdl.handle.net/10161/21237Published Version (Please cite this version)
10.5194/esurf-5-841-2017Publication Info
Brantley, SL; McDowell, WH; Dietrich, WE; White, TS; Kumar, P; Anderson, SP; ... Gaillardet,
J (2017). Designing a network of critical zone observatories to explore the living skin of the
terrestrial Earth. Earth Surface Dynamics, 5(4). pp. 841-860. 10.5194/esurf-5-841-2017. Retrieved from https://hdl.handle.net/10161/21237.This is constructed from limited available data and may be imprecise. To cite this
article, please review & use the official citation provided by the journal.
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Show full item recordScholars@Duke
Daniel D. Richter
Professor in the Division of Earth and Climate Science
Richter’s research and teaching links soils with ecosystems and the wider environment,
most recently Earth scientists’ Critical Zone. He focuses on how humanity is transforming
Earth’s soils from natural to human-natural systems, specifically how land-uses alter
soil processes and properties on time scales of decades, centuries, and millennia.
Richter's book, Understanding Soil Change (Cambridge University Press), co-authored
with his former PhD

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