Long-term warming in a Mediterranean-type grassland affects soil bacterial functional potential but not bacterial taxonomic composition

Ying Gao,Mengting Yuan,Chris Field,Zhou Shi,Junjun Ding,Audrey Niboyet,Jizhong Zhou,Baohua Gu,Nona Chiariello,Qi Qi,Xavier Le Roux,Kathryn Docherty,Jessica Gutknecht,Yunfeng Yang,Qun Gao,Bruce A Hungate

doi:10.1038/s41522-021-00187-7

Abstract

Climate warming is known to impact ecosystem composition and functioning. However, it remains largely unclear how soil microbial communities respond to long-term, moderate warming. In this study, we used Illumina sequencing and microarrays (GeoChip 5.0) to analyze taxonomic and functional gene compositions of the soil microbial community after 14 years of warming (at 0.8–1.0 °C for 10 years and then 1.5–2.0 °C for 4 years) in a Californian grassland. Long-term warming had no detectable effect on the taxonomic composition of soil bacterial community, nor on any plant or abiotic soil variables. In contrast, functional gene compositions differed between warming and control for bacterial, archaeal, and fungal communities. Functional genes associated with labile carbon (C) degradation increased in relative abundance in the warming treatment, whereas those associated with recalcitrant C degradation decreased. A number of functional genes associated with nitrogen (N) cycling (e.g., denitrifying genes encoding nitrate-, nitrite-, and nitrous oxidereductases) decreased, whereas nifH gene encoding nitrogenase increased in the warming treatment. These results suggest that microbial functional potentials are more sensitive to long-term moderate warming than the taxonomic composition of microbial community.

Highlights

Accumulating concentrations of greenhouse gases in the atmosphere are increasing global surface temperature, which is expected to persist in the coming decades[1]
Plant standing biomass (PSB), a measure of plant growth consisting of the sum of aboveground biomass, litter, shallow roots, and fine roots, was not altered by the warming treatment
Our results showed that after 14-year of experimental treatment, warming had no detectable effect on the taxonomic composition and alpha-diversity of soil bacterial and archaeal communities (Supplementary Fig. 1a and Supplementary Table 1)

Summary

Introduction

Accumulating concentrations of greenhouse gases in the atmosphere are increasing global surface temperature, which is expected to persist in the coming decades[1]. Warming often stimulates plant photosynthesis, biomass, and growth[2,3,4,5], and alters plant community composition[6,7]. Soil C and N cycling are altered by warming[8,9,10,11]. Many studies have analyzed the effect of brief heat shocks (often applied over a few minutes or hours)[12,13]; or warm climate spells (typically applied over a few days or weeks)[14,15]; on soil microbial communities. Studies analyzing the effect of moderate and progressive warming on a long term (over years to decades), as currently experienced due to global warming, are very scarce

Objectives

Results

Conclusion