Long-term warming of a forest soil reduces microbial biomass and its carbon and nitrogen use efficiencies

authored by

Ye Tian, Andreas Schindlbacher, Carolina Urbina Malo, Chupei Shi, Jakob Heinzle, Steve Kwatcho Kengdo, Erich Inselsbacher, Werner Borken, Wolfgang Wanek

Abstract

Global warming impacts biogeochemical cycles in terrestrial ecosystems, but it is still unclear how the simultaneous cycling of carbon (C) and nitrogen (N) in soils could be affected in the longer-term. Here, we evaluated how 14 years of soil warming (+4 °C) affected the soil C and N cycle across different soil depths and seasons in a temperate mountain forest. We used H₂¹⁸O incorporation into DNA and ¹⁵N isotope pool dilution techniques to determine gross rates of C and N transformation processes. Our data showed different warming effects on soil C and N cycling, and these were consistent across soil depths and seasons. Warming decreased microbial biomass C (−22%), but at the same time increased microbial biomass-specific growth (+25%) and respiration (+39%), the potential activity of β-glucosidase (+31%), and microbial turnover (+14%). Warming reduced gross rates of protein depolymerization (−19%), but stimulated gross N mineralization (+63%) and the potential activities of N-acetylglucosaminidase (+106%) and leucine-aminopeptidase (+46%), and had no impact on gross nitrification (+1%). Microbial C and N use efficiencies were both lower in the warming treatment (−15% and −17%, respectively). Overall, our results suggest that long-term warming drives soil microbes to incorporate less C and N into their biomass (and necromass), and to release more inorganic C and N to the environment, causing lower soil C and N storage in this forest, as indicated by lower soil C and total N contents. The decreases in microbial CUE and NUE were likely triggered by increasing microbial P constraints in warmed soils, limiting anabolic processes and microbial growth and promoting pervasive losses of C and N from the soil.

Organisation(s)

Institute of Soil Science

External Organisation(s)

University of Vienna
Natural Hazards and Landscape (BFW)
University of Bayreuth
University of Natural Resources and Applied Life Sciences (BOKU)
University of Amsterdam

Type

Article

Journal

Soil Biology and Biochemistry

Volume

184

ISSN

0038-0717

Publication date

09.2023

Publication status

Published

Peer reviewed

Yes

ASJC Scopus subject areas

Microbiology, Soil Science

Sustainable Development Goals

SDG 15 - Life on Land

Electronic version(s)

https://doi.org/10.1016/j.soilbio.2023.109109 (Access: Open)