Necromass responses to warming

A faster microbial turnover in favor of soil carbon stabilisation

authored by

Jie Zhou, Yuan Liu, Chunyan Liu, Kazem Zamanian, Wenhao Feng, Samuel K. Steiner, Lingling Shi, Thomas Guillaume, Amit Kumar

Abstract

Microbial byproducts and residues (hereafter ‘necromass’) potentially play the most critical role in soil organic carbon (SOC) sequestration. However, little is known about the influence of climate warming on necromass accumulation in the agroecosystem and the underlying mechanisms associated with microbial life strategies. In order to address these knowledge gaps, we used amino sugars as biomarkers of microbial necromass, and investigated their variation through an 8-year trial in an agroecosystem with two warming levels (+1.6 and + 3.2 °C) compared to ambient temperature. The results showed that the lower warming level had no impact on total microbial necromass carbon. Conversely, warming the soil 3.2 °C above ambient increased total microbial necromass by 17 % and its contribution to SOC by 21.3 %, mainly by increasing fungal necromass (+19.8 %), whereas +3.2 °C warming had no impact on bacterial necromass. At the phylum level, compared with the ambient control, +3.2 °C warming induced an increase in the abundance of Proteobacteria and a decrease in both Acidobacteria and Actinobacteria, whereas in the fungal community, Ascomycota increased and Mortierellomycota decreased. This indicates that r-strategists outcompete K-strategists in warmer climates, which led to increased microbial necromass production and accumulation, as supported by the positive correlation between r-strategists and microbial necromass. Stronger microbial competition for resources also resulted in a higher biomass turnover rate, greater cell death, and greater production of microbial necromass. This was supported by the lower bacterial and fungal network complexity and trophic links under warming conditions. In addition, the necromass generated from accelerated microbial turnover further offsets warming-induced deceases in microbial biomass. Consequently, bulk SOC did not change, despite microbial necromass having a much greater response to warming than the soil C pool. Therefore, future climate warming may influence the composition and persistence of SOC during microbial degradation.

Organisation(s)

Institute of Soil Science

External Organisation(s)

Nanjing Agricultural University
Lawrence Livermore National Laboratory
Nanjing Institute of Agricultural Sciences in Jiangsu Hilly Area
Chinese Academy of Agricultural Sciences
Agroscope
University of Tübingen
United Arab Emirates University

Type

Article

Journal

Science of the Total Environment

Volume

954

ISSN

0048-9697

Publication date

05.10.2024

Publication status

E-pub ahead of print

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.2024.176651 (Access: Closed)