Weathering by mycorrhizal fungi defines a threshold for nutrients in ecosystems along an aridity gradient

authored by

Doreen Fleck, Simon Thiedau, Diana Boy, Leopold Sauheitl, Svenja Stock, Moritz Köster, Ralf Oeser, Michaela A. Dippold, Sandra Spielvogel, Yakov Kuzyakov, Yosef Steinberger, Roberto Godoy, Francisco Javier Matus, Georg Guggenberger, Jens Boy

Abstract

The Earth's surface is in constant change due to biotic and abiotic processes. During the last decades awareness arose that these biotic and abiotic processes might intensely interfere. Biogenic weathering, the acceleration of mineral weathering by autotroph-symbiont couples fuelled by photoassimilates for the sake of an equilibrated nutrient supply of involved biota, potentially drives denudation rates at ecosystem level. Our experiment aimed to examine how aridity affects biogenic weathering. The study was conducted along a gradient in Chile from humid to hyperarid climate (Atacama Desert), where photoassimilate production is increasingly limited by water stress. We hypothesize that biogenic weathering would cease if a threshold between element loss from denudation and energy demand for additional nutrient element mobilization by biogenic weathering is crossed, as competition between life for these elements becomes less intense when water supply limits biomass growth increasingly. We buried mesh bags containing freshly broken minerals, including biotite, muscovite and apatite along the gradient in Chile on granitic bedrock. Unexpectedly and in contrast to our initial hypothesis, we found that mineral weathering rates driven by mycorrhizal fungi under arid conditions were even proportionally higher, indicating a comparatively higher investment of photoassimilates into biogenic weathering by desert plants than by mediterranean, suggesting an adaptive mechanism. Additionally, biogenic weathering occurred at constant rates over a depth of up to 2.3 m, illustrating the constant mining of mycorrhizal fungi, irrespective of overall biological activity along the soil profile. The relative importance of biogenic weathering in arid climates furthermore points towards a fundamental function of biogenic weathering beyond nutrient mobilization by suggesting a regulatory role in overcoming long periods of missing soil water that prevent nutrient exchange from the soil matrix.

Organisation(s)

Institute of Earth System Sciences
Institute of Microbiology

External Organisation(s)

University of Tübingen
University of Göttingen
GFZ Helmholtz Centre for Geosciences
Kiel University
Bar-Ilan University
Universidad Austral de Chile
Universidad de la Frontera

Type

Article

Journal

Science of the Total Environment

Volume

990

ISSN

0048-9697

Publication date

15.08.2025

Publication status

Published

Peer reviewed

Yes

ASJC Scopus subject areas

Environmental Engineering, Environmental Chemistry, Waste Management and Disposal, Pollution

Sustainable Development Goals

SDG 13 - Climate Action

Electronic version(s)

https://doi.org/10.1016/j.scitotenv.2025.179891 (Access: Open)