Soil processes and functions across an international network of Critical Zone Observatories: Introduction to experimental methods and initial results

Banwart, Steven A.; Menon, Manoj; Bernasconi, Stefano M.; Bloem, J.; Blum, Winfried E. H.; Souza, Danielle Maia de; Davidsdotir, Brynhildur; Duffy, Christopher; Lair, Georg J.; Krám, Pavel; Lamačová, Anna; Lundin, Lars; Nikolaidis, Nikolaos P.; Novák, Martin; Panagos, Panos; Ragnarsdottir, KV; Reynolds, B.; Robinson, David A.; Rousseva, Svetla; Ruiter, Peter de; Gaans, Pauline van; Weng, Liping; White, Tim; Zhang, Bin

doi:10.1016/j.crte.2012.10.007

Cited by 69 publications

(46 citation statements)

References 38 publications

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“…This model would answer the need for long-term measurements (at carefully chosen hubs), the need for short-term targeted measurements at specific locations both within the United States and abroad (carefully chosen campaign sites), and the need for new mechanisms to engage more investigators (funding to bring in scientists from outside the hub network). This long- term hub and short-term campaign emphasis has been promoted in the literature by researchers both inside and outside the current CZO funding framework (Banwart et al, 2012;Larsen et al, 2015). Fundamentally, the argument for the hub-and-campaign approach is that the two methods benefit from each other.…”

Section: The Future Networkmentioning

confidence: 99%

Designing a network of critical zone observatories to explore the living skin of the terrestrial Earth

et al. 2017

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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.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 observatoriesPublished by Copernicus Publications on behalf of the European Geosciences Union. 842 S. L. Brantley et al.: Designing a network of critical zone 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 "hubs-and-campaigns" 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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Section: The Future Networkmentioning

confidence: 99%

Designing a network of critical zone observatories to explore the living skin of the terrestrial Earth

et al. 2017

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“…Observatory networks (Anderson et al, 2008;Banwart et al, 2012;Weathers et al, 2016;Brantley et al, 2017b) probably provide the only way to investigate all the chemical, physical, and biological processes that are affected by trees. For example, the hypotheses stated here should be tested across the growing network of critical zone observatories.…”

Section: Conclusion and A Vision For Moving Forwardmentioning

confidence: 99%

Reviews and syntheses: on the roles trees play in building and plumbing the critical zone

et al. 2017

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Abstract. Trees, the most successful biological power plants on earth, build and plumb the critical zone (CZ) in ways that we do not yet understand. To encourage exploration of the character and implications of interactions between trees and soil in the CZ, we propose nine hypotheses that can be tested at diverse settings. The hypotheses are roughly divided into those about the architecture (building) and those about the water (plumbing) in the CZ, but the two functions are intertwined. Depending upon one's disciplinary background, many of the nine hypotheses listed below may appear obviously true or obviously false. (1) Tree roots can only physically penetrate and biogeochemically comminute the immobile substrate underlying mobile soil where that underlying substrate is fractured or pre-weathered. (2) In settings where the thickness of weathered material, H , is large, trees primarily shape the CZ through biogeochemical reactions within the rooting zone. (3) In forested uplands, the thickness of mobile soil, h, can evolve toward a steady state because of feedbacks related to root disruption and tree throw. (4) In settings where h H and the rates of uplift and erosion are low, the uptake of phosphorus into trees is buffered by the fine-grained fraction of the soil, and the ultimate source of this phosphorus is dust. (5) In settings of limited water availability, trees maintain the highest length density of functional roots at depths where water can be extracted over most of the growing season with the least amount of energy expenditure. (6) Trees grow the majority of their roots in the zone where the most growth-limiting resource is abundant, but they also grow roots at other depths to forage for other resources and to hydraulically redistribute those resources to depths where they can be taken up more efficiently. (7) Trees rely on matrix water in the unsaturated zone that at times may have anPublished by Copernicus Publications on behalf of the European Geosciences Union. 5116 S. L. Brantley et al.: Reviews and syntheses: on the roles trees play in building and plumbing the critical zone isotopic composition distinct from the gravity-drained water that transits from the hillslope to groundwater and streamflow. (8) Mycorrhizal fungi can use matrix water directly, but trees can only use this water by accessing it indirectly through the fungi. (9) Even trees growing well above the valley floor of a catchment can directly affect stream chemistry where changes in permeability near the rooting zone promote intermittent zones of water saturation and downslope flow of water to the stream. By testing these nine hypotheses, we will generate important new cross-disciplinary insights that advance CZ science.

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“…2). Within this chronosequence, the age of the soils increases with increasing distance from the Danube River, ranging from the youngest soils on fresh sediments to Chernozems more than eight thousand years old (BANWART et al, 2012). The soil age was dated using 137 Cs, optically stimulated luminescence (OSL), the crystallinity of Fe-oxides (Feo/Fed) and archeological remnants (LAIR et al, 2009).…”

Section: Research Area and Soilsmentioning

confidence: 99%

Persistence of soil organic matter and soil structure

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Soil processes and functions across an international network of Critical Zone Observatories: Introduction to experimental methods and initial results

Cited by 69 publications

References 38 publications

Designing a network of critical zone observatories to explore the living skin of the terrestrial Earth

Designing a network of critical zone observatories to explore the living skin of the terrestrial Earth

Reviews and syntheses: on the roles trees play in building and plumbing the critical zone

Persistence of soil organic matter and soil structure

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