Chemistry and microbiology of the Critical Zone along a steep climate and vegetation gradient in the Chilean Coastal Cordillera

verfasst von

Ralf A. Oeser, Nicole Stroncik, Lisa Marie Moskwa, Nadine Bernhard, Mirjam Schaller, Rafaella Canessa, Liesbeth van den Brink, Moritz Köster, Emanuel Brucker, Svenja Stock, Juan Pablo Fuentes, Roberto Godoy, Francisco Javier Matus, Rómulo Oses Pedraza, Pablo Osses McIntyre, Leandro Paulino, Oscar Seguel, Maaike Y. Bader, Jens Boy, Michaela A. Dippold, Todd A. Ehlers, Peter Kühn, Yakov Kuzyakov, Peter Leinweber, Thomas Scholten, Sandra Spielvogel, Marie Spohn, Kirstin Übernickel, Katja Tielbörger, Dirk Wagner, Friedhelm von Blanckenburg

Abstract

The Chilean Coastal Cordillera features a spectacular climate and vegetation gradient, ranging from arid and unvegetated areas in the north to humid and forested areas in the south. The EarthShape project (“Earth Surface Shaping by Biota”) uses this natural gradient to investigate how climate and biological processes shape the Earth's surface. We explored the Critical Zone, the Earth's uppermost layer, in four key sites located in desert, semidesert, Mediterranean, and temperate climate zones of the Coastal Cordillera, with the focus on weathering of granitic rock. Here, we present first results from 16 approximately 2 m-deep regolith profiles to document: (1) architecture of weathering zone; (2) degree and rate of rock weathering, thus the release of mineral-derived nutrients to the terrestrial ecosystems; (3) denudation rates; and (4) microbial abundances of bacteria and archaea in the saprolite. From north to south, denudation rates from cosmogenic nuclides are ~10 t km⁻² yr⁻¹ at the arid Pan de Azúcar site, ~20 t km⁻² yr⁻¹ at the semi-arid site of Santa Gracia, ~60 t km⁻² yr⁻¹ at the Mediterranean climate site of La Campana, and ~30 t km⁻² yr⁻¹ at the humid site of Nahuelbuta. A and B horizons increase in thickness and elemental depletion or enrichment increases from north (~26°S) to south (~38°S) in these horizons. Differences in the degree of chemical weathering, quantified by the chemical depletion fraction (CDF), are significant only between the arid and sparsely vegetated site and the other three sites. Differences in the CDF between the sites, and elemental depletion within the sites are sometimes smaller than the variations induced by the bedrock heterogeneity. Microbial abundances (bacteria and archaea) in saprolite substantially increase from the arid to the semi-arid sites. With this study, we provide a comprehensive dataset characterizing the Critical Zone geochemistry in the Chilean Coastal Cordillera. This dataset confirms climatic controls on weathering and denudation rates and provides prerequisites to quantify the role of biota in future studies.

Organisationseinheit(en)

Institut für Bodenkunde
AG Bodenchemie

Externe Organisation(en)

Helmholtz-Zentrum Potsdam Deutsches GeoForschungsZentrum (GFZ)
Eberhard Karls Universität Tübingen
Philipps-Universität Marburg
Georg-August-Universität Göttingen
Universität Bayreuth
Universidad de Chile
Universidad Austral de Chile
Universidad de la Frontera
Centro de Estudios Avanzados en Zonas Áridas (CEAZA)
Universidad de Atacama (UAD)
Pontificia Universidad Catolica de Chile
Universidad de Concepcion
Universität Rostock
Christian-Albrechts-Universität zu Kiel (CAU)
Universität Potsdam
Freie Universität Berlin (FU Berlin)

Typ

Artikel

Journal

Catena

Band

170

Seiten

183-203

Anzahl der Seiten

21

ISSN

0341-8162

Publikationsdatum

11.2018

Publikationsstatus

Veröffentlicht

Peer-reviewed

Ja

ASJC Scopus Sachgebiete

Erdoberflächenprozesse

Ziele für nachhaltige Entwicklung

SDG 15 – Lebensraum Land

Elektronische Version(en)

https://gfzpublic.gfz-potsdam.de/pubman/item/item_3318890_3/component/file_3342890/3318890.pdf (Zugang: Offen)
https://doi.org/10.1016/j.catena.2018.06.002 (Zugang: Geschlossen)