Soil microbial abundance and activity across forefield glacier chronosequence in the Northern Patagonian Ice Field, Chile

ABSTRACT

In recently deglaciated soils, microbial organisms drive soil transformations by increasing carbon (C) and nitrogen (N) pools while depleting available phosphorous (P), thus improving plant colonization and soil development. However, the rate of soil development can vary in response to local environmental conditions that affect microbial abundance and activity. In this contribution we use observational and experimental approaches to evaluate the interplay between soil biogeochemical features and microbial abundance and function after approximately seventy years of soil development in the forefield of the Exploradores Glacier that is located at the northernmost end of the Northern Patagonian Ice Field. Our findings suggest that after approximately seventy years of soil development, microbial abundance and soil C and N accumulation increase with soil age, soil bulk density and pH decreased, and microbial activity measured as soil chlorophyll a and nifH gene abundance increased. In turn, decomposition increased with fungal abundance, showing higher values in the late stages of soil development where the soil C:N ratio was higher and soil pH was lower. Overall, biogeochemical changes along this chronosequence followed the predicted pattern, with gradual increases in soil nutrients and microbial abundance, in addition to decomposition processes.

KEYWORDS:

• Archaea
• bacteria
• fungi
• soil development
• Andean

Acknowledgments

We thank Benjamin Glasner for field assistance. Research reported here are contributions to the program of the Long-Term Socio-Ecological Research Network- Chile (LTSER-Chile) and the Red de Centros y Estaciones Regionales de Investigación, RECER UC, Pontificia Universidad Católica de Chile. The authors gratefully acknowledge the work of the Observatoire homme-milieux International, Patagonia-Bahía Exploradores (OHM-I, INEE, CNRS and the Estación Patagonia UC, Pontificia Universidad Católica de Chile).

Author contributions

FDA, AG, and PMA: Study and sampling design. FDA, CB, MM, and JLG: Sample preparation and fieldwork. FDA, JLG, CB, and KR: Data analysis. FDA, AG with input from all coauthors: Manuscript preparation.

Disclosure statement

No potential conflict of interest was reported by the authors.

Supplementary material

Supplemental data for this article can be accessed on the publisher’s website.

Additional information

Funding

This study was partly funded by the LabEx DRIIHM, French Programme “Investissements d'Avenir” (ANR-11-LABX-0010) which is managed by the French National Research Agency. FDA and AS-B received support from FONDECYT 1191865. FDA, AG & PAM were supported by Grants ICMMINECON, P05-002 and CONICYT AFB-170008 (Chile) to the Institute of Ecology and Biodiversity. JLG received support from FONDECYT 1161110. FDA was supported by Vicerrectoría de Investigación (VRI), Universidad Mayor, Chile.