Designing a network of critical zone observatories to explore the living skin of the terrestrial Earth
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 ca...
| Main Authors: | , , , , , , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2017-12-01
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| Series: | Earth Surface Dynamics |
| Online Access: | https://www.earth-surf-dynam.net/5/841/2017/esurf-5-841-2017.pdf |
| Summary: | 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. |
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| ISSN: | 2196-6311 2196-632X |