Fungal genetic biodiversity and metabolic activity as an indicator of potential biological weathering and soil formation – Case study of towards a better understanding of Earth system dynamics

Abstract

Terrestrial plants act as ecosystem engineers modifying the flow of energy and matter and creating new habitats for other organisms. This vital concept also encompasses plants' effects on landforms and soils, crucial components of forested landscapes worldwide. In the present study, we investigate how trees through their roots and symbiotic organisms influence soil-weathering processes. The aim of the study was to answer one of the big questions in Earth sciences: how do biological agents, including fungi, acting at the critical interface between the biosphere and the abiotic environment, shape soil and landscape evolution? Within the present study we ask what is the level of fungal activity within root systems of trees and how can it influence biological weathering. The area of interest is in the Poprad River gorge in the southern part of the Sącz Beskidy Mountains, the Outer Western Carpathians. We applied the following analyses: 1) determination of the structural diversity of fungi (ITS1) and 2) assessment of the metabolic profile of soils (Biolog FFPlates). The highest average number of classified genera were fungi which simultaneously carried out pathotrophic, saprotrophic and symbiotrophic functions. Boletales, Agaricales, Cantharellales and Archaeorhizomycetales were the most abundant orders, but in one sample we also found a particularly high proportion of the order Mortierellales. The order Boletales and its family Boletaceae were significantly enriched in rock crack samples, whereas the highest number of differentially abundant taxa was observed in reference samples. The most frequently utilised substrates by fungi were: glycyl-L-glutamic acids, L-ornithine, L-phenylalanine, L-proline, D-galacturonic acid, fumaric acids, D-saccharic acids, succinic acids and N-acetyl-D-glucosamine. Our study demonstrates that the fungal community in the root zone is geochemically active and the organic acids secreted by plant roots in oligotrophic conditions and nutrient limitations significantly affect soil weathering.