From Microbes to Morphology: Incorporating Microbial Activity into Surface Process Geomorphology

Résumé fourni par la source

This review presents microbial geomorphology as a quantitative component of process geomorphology, introducing microbial weathering from a geomicrobiological mechanism into the mathematical models of landscape evolution. Despite extensive documentation of microbial weathering mechanisms and their roles in nutrient cycling and sustaining ecosystems, the consequences of microbial rock weathering and soil formation for landscape evolution remain unquantified. Here, we synthesize observations of microbial weathering mechanisms and identify a scale gap between microbial metabolic timescales and those of landscape formation as the central obstacle to incorporating them into geomorphology theory. Drawing on existing research, we argue that community-level change, not individual metabolic processes, is the scale at which this gap can be bridged, and propose connecting microbial weathering to the soil production function through a growth-limiting biotic weathering term. Coupled with the established abiotic term, this yields a humped soil production curve, providing a quantitative mechanism for the initial increase in soil production that the abiotic soil production equation does not capture. Pulling together microbiology and surface-process geomorphology, we lay out the open questions and future research directions central to answering a fundamental question in Earth sciences: what is the fingerprint of microbial life on Earth's landscapes?

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